vol34no7

July 2012 Vol. 34 No. 7

30 Creating Decorative Floors...and a Dinosaur, Too

CI_2_12

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Concrete international july 2012 1

Descriptions of ACI Certification Programs — Includes program requirements and reference/ resource materials.

Schedule of Upcoming/Testing Sessions — Search by program and/or state.

Directory of Certified Individuals— Confirm an individual’s certification and date of expiration.

Visit www.ACICertification.org for:

Next Time...

specify ACI Certified personnelSince 1980, ACI has tested over 350,000 concrete technicians, inspectors, supervisors, and craftsmen in 17 different certification programs.

When you have a need for qualified concrete professionals—specify ACI Certification.

CCRL LAb ToURThe Cement and Concrete Reference Laboratory offers performance examinations for the ACI Concrete Strength Testing Technician and ACI Aggregate Testing Technician – Level 1 certification programs.Upcoming tour locations are:

To schedule your lab for CCRL inspection, and to arrange for performance testing, contact Jan Prowell at (301) 975-6704.

July 2012ArkansasIowaKansasMissouriNebraskaNorth DakotaOklahomaWestern Canada

August 2012KansasMontanaNebraskaOklahomaSouth Dakota

Concrete international JULy 2012 3

July 2012 Vol. 34 No. 7

43

FlOORS & FOuNDATIONS

30 Creating Decorative Floors…and a Dinosaur, TooArtistry and altruism displayed at the Concrete Decor Show

35 understanding Windbreak PrinciplesRequired height and length for typical placements may surprise youby Bruce A. Suprenant and Ward R. Malisch

40 Optimum Slab-on-Ground ConcreteLowering the water content of a minimized paste volume reduces curlingby Daniel M. Vruno and Michael J. Ramerth

46 Self-leveling Floor Topping Saves the DaysSystem helps shave months off the construction schedule for a medical center by Brad Fulkerson

50 Precooling Mass Concrete with liquid NitrogenAutomated system leads to increased use of the technologyby John Gajda and Francisco Sumodjo

AlSO FEATuRING

23 ACI Student Fellowships, Scholarships for 2012-2013Applications for next year can now be submitted

26 SDC’s New Chair and Board Members

28 Concrete Reinforcing Steel Institute Announces 2012 Design Award Winners

53 use of Siliceous Aggregates in Concrete—Texas Experience, Part 1

Mineralogy, morphology, microstructure, and reactivity by Hugh Wang and Elizabeth (Lisa) Lukefahr

74 Concrete Q&AFinishing lightweight air-entrained concrete

32

4 july 2012 Concrete international

July

Concrete international

departments6 Educational Seminars

7 President’s Memo

10 News

16 Chapter Reports

18 ACI Committee Document Abstracts

20 On the Move

22 Industry Focus

59 Products & Practice

62 Product Showcase

64 Calls for Papers

66 Bookshelf

67 What’s New, What’s Coming

68 Meetings

69 Spanish Translation Synopses

71 Membership Application

72 Bulletin Board

73 Public Discussion

73 Advertisers’ Index

50

AMERICAN CONCRETE INSTITuTEhttp://www.concrete.org

Tel. (248) 848-3700Fax. (248) 848-3150

In February of this year, the building and grounds at SAY Sí, a nonprofit multidisciplinary arts program established for the youth of San Antonio, TX, benefited from a decorative concrete makeover during workshops and courses of the Concrete Decor Show. In the Black Box Theatre—the performance space of the facility—the floor received applications of various metallic epoxies and polyaspartics. For more on the artistry in concrete showcased in the projects, see the article “Creating Decorative Floors…and a Dinosaur, Too” on p. 30. (Photo by Keith A. Tosolt, Managing Editor, Concrete International.)

PuBlIShERjohn C. Glumb, CAE

([email protected])

EDITOR-IN-ChIEF Rex C. Donahey, PE, lEED AP

([email protected])

ENGINEERING EDITOR W. Agata Pyc

([email protected])

MANAGING EDITORKeith A. Tosolt

([email protected])

EDITORIAl ASSISTANTKaitlyn j. Hinman

([email protected])

ADVERTISINGjeff Rhodes

Network Media Partners, Inc.([email protected])

Publishing services

MANAGERBarry M. Bergin

EDITORS Carl R. Bischof (Senior Editor),

Karen Czedik, Kelli R. Slayden, Denise E. Wolber

GRAPhIC DESIGNERSGail l. Tatum (Senior Designer),

Susan K. Esper, Colleen E. Hunt, Ryan M. jay

PuBlIShING ASSISTANTDaniela A. Bedward

Copyright © 2012 American Concrete Institute. Printed in the United States of America. All correspondence should be directed to the headquarters office: P.O. Box 9094, Farmington Hills, MI 48333-9094. Telephone: (248) 848-3700. Facsimile (FAX): (248) 848-3701. Concrete International (US ISSN 0162-4075) is published monthly by the American Concrete Institute, 38800 Country Club Drive, Farmington Hills, Mich. 48331. Periodicals postage paid at Farmington, Mich., and at additional mailing offices. Concrete International has title registration ® with the U.S. Patent Trademark Office. Subscription rates: $161 per year (U.S. and possessions); $170 (elsewhere) payable in advance: single copy price is $26.00 for nonmembers, $19.00 for ACI members, both prepaid. POSTMASTER: send address changes to Concrete International, P.O. Box 9094, Farmington Hills, MI 48333-9094. The Institute is not responsible for the statements or opinions expressed in its publications. Institute publications are not able to, nor intended to supplant individual training, responsibility, or judgment of the user, or the supplier, of the information presented. Permission is granted by the American Concrete Institute for libraries and other users registered with the Copyright Clearance Center (CCC) to photocopy any article herein for the fee of $3.00 per transaction. Payments marked ISSN 0162-4075/97 should be sent directly to the Copyright Clearance Center, 21 Congress St., Salem, MA. 01970. Copying done for other than personal or internal reference use without the express permission of the American Concrete Institute is prohib ited. Requests for special permission or bulk copying should be addressed to the Publisher, Concrete International, American Concrete Institute. Canadian GST #126213149RT

Concrete international JULy 2012 5

IN CiJuly 2012

We normally try to evaluate risk in terms of the costs and rewards of minimizing it. The

construction of concrete flatwork carries a large number of risks, including plastic shrinkage cracking, changes in surface topography as the result of external or internal effects, poor finishability, localized delamination, or moisture damage to flooring. The construction of structures exposed to moisture also carries numerous risks, including freezing and thawing damage and alkali-silica reaction. In this issue of CI, our contributors discuss these risks and measures to mitigate them.

The costs of minimizing risks can be difficult to quantify, and they can’t be analyzed without considering their effects on the total project (system). Using a windbreak to minimize the risk of cracking, for example, may carry a high cost. Perhaps other methods can achieve the goal more economically. Using a topping course to eliminate the risk of an uneven surface finish may come at a high cost in terms of the cost of constructing an elevated slab on metal deck. Ensuring a very flat working platform and substrate for final finishes, however, can result in great time savings and installation efficiencies.

Admittedly these examples provide only anecdotal evidence, but they do support the argument that a simple risk analysis may be the biggest risk of all.

Rex C. Donahey

Board of Direction

Neal S. AndersonKhaled W. AwadRoger J. Becker

Jeffrey W. ColemanRobert J. FroschJames R. Harris

PresidentJames K. Wight

Vice Presidents

technical actiVities committee

chair

David A. Lange

secretary

Daniel W. Falconer

Sergio M. AlcocerJoAnn P. BowningChiara F. Ferraris

Catherine E. FrenchTrey Hamilton

Ronald J. JanowiakKevin A. MacDonald

Antonio NanniJan Olek

Michael M. SprinkelPericles C. StivarosEldon G. Tipping

Luis E. GarcíaFlorian G. Barth

Kenneth C. Hover

Anne M. Ellis William E. Rushing Jr.

directors

Past President Board memBers

American Concrete Institute

educational actiVities committee

chair

David M. Suchorski

staff liaison

Michael L. Tholen

Alejandro Duran-HerreraMary Beth HuesteFrances T. Griffith

Tarek S. KahnKimberly E. KurtisThomas O. Malerk

John J. MyersWilliam D. Palmer Jr.

Lawrence L. SutterLawrence H. TaberDavid W. Whitmore

certification Programscommittee

chair

George R. Wargo

staff liaison

John W. Nehasil

Khaled W. AwadRoger J. Becker

Heather J. BrownCesar A. Constantino

Alejandro Duran-Herrera J. Mitchell Englestead

Brian GreenFrances T. Griffith Charles S. Hanskat

Joe Hug Thomas O. Malerk

Ed T. McGuire William D. Palmer Jr.

John J. Schemmel Vinicio SuarezEldon Tipping

Cecil L. JonesSteven H. Kosmatka

David A. LangeDenis Mitchell

Jack MoehleDavid H. Sanders

Certification and chapters:John W. Nehasil, Managing Director ([email protected])

Customer and member support:Melinda G. Reynolds, Manager ([email protected])

Engineering: Daniel W. Falconer, Managing Director ([email protected])

Finance and administration:Donna G. Halstead, Managing Director ([email protected])

Publishing and event services:Renée J. Lewis, Director ([email protected])

aci staff

Professional development: Michael L. Tholen, Managing Director ([email protected])

Sales and membership:Diane L. Baloh, Director ([email protected])

Strategic Development Council/ Marketing, sales, and industry relations:Douglas J. Sordyl, Managing Director ([email protected])

Sustainability:Kevin P. Mlutkowski, Director ([email protected])

Executive Vice President: Ronald Burg ([email protected])Senior Managing Director: John C. Glumb ([email protected])

Ronald BurgexecutiVe Vice President

See pages 8-9 for a list of ACI’s Sustaining Members.

To learn more about our sustaining members, go to the ACI Web site at

www.concrete.org/members/mem_sustaining.htm.

sustaining memBers

6 juNE 2012 Concrete international

ACI Custom SeminarsConvenienceyou schedule training whenever it works best for your organization and your employees. you name the location, the time, and the topic, and we’ll make it happen!

Cost-effectivenessRealize savings by eliminating the high costs associated with employee travel and lodging. We bring the seminar to your door!

Expert instructorsExcellence in the field you choose. Each custom seminar is usually conducted by two instructors who are recognized experts in their field.

State-of-the-art publicationsThe latest publications prepared by one of more than 130 ACI technical committees can supplement the speaker handouts. ACI publications are available at a 50% discount.

FeesSeminar fees start at $7600 for a 1-day (7.5 hour) seminar. Numerous topics are ready to go. Any concrete-related topic can be created and custom-designed to meet your specific organizational needs at an additional cost. Ask about discounts for ACI organizational and sustaining members.

ContactEva Korzeniewski, Seminar Coordinator American Concrete Institute P.O. Box 9094 Farmington Hills, MI 48333-9094 Phone: 248-848-3754 Fax: 248-848-3792 [email protected] www.concreteseminars.com

TopicsACI/PCA 318-11 Building Code Requirements for Structural Concrete

ACI/PCA Simplified Design of Concrete Buildings of Moderate Size and Height

ACI/PCI Design and Construction of Concrete Parking Structures

Basics of Concrete Materials and Testing

Concrete Repair Basics

Construction of Concrete Slabs-on-Ground

Design of Concrete Slabs-on-Ground

Environmental Engineering Concrete—Design and Details

Portland Cement Concrete Overlays: State of the Technology

Reinforced Concrete Design

Repair of Concrete Bridges, Parking Decks, and Other Transportation Structures

Repair of Concrete Workshop

Seismic and Wind Design Considerations for Concrete Buildings

Seismic Design of Liquid-Containing Concrete Structures

Troubleshooting Concrete Construction

Troubleshooting Concrete Floor Problems

Troubleshooting Concrete Forming and Shoring

Physical Tester—Basics of Cement Testing

ACI Custom SeminarsPersonalized training to fit your organization’s needs and goals

For more information regarding available Custom Seminar topics,

visit www.concreteseminars.com and click on Custom Seminars.

NEW!


President’s

Memo

James K. Wight, ACI President

I recently had the privilege of participating in the College of Engineering

graduation at the University of Michigan. It’s an exciting event with a full range of emotions. Young people are completing one phase of their lives and embarking upon the next. Clearly there is joy in saying “mission accomplished,” but there are some anxious feelings about facing tomorrow’s new challenges.

In many respects, the officer transitions we go through within ACI are very similar to graduation exercises. For the outgoing officers, there is pride and honor in what has been accomplished. For the incoming officers, there is both excitement and apprehension. Most new officers and committee Chairs are confident of their abilities, but a little fearful of what unknown challenges may lie ahead.

ACI goes through its leadership transitions at the end of the Spring Convention. New committee Chairs are promoted, new members are added to the Board of Direction, and a new President starts his or her 1-year term. Similar transitions occur with all of the ACI Chapters, usually in the spring as the annual cycle of programs and meetings is coming to an end. I’m sure the new leaders at all levels within ACI are well-prepared and confident, but also a little nervous about keeping everything on course.

I recently attended a Chapter Roundtable in Phoenix, AZ, and had a chance to interact with many relatively new Chapter Officers and local Board members. They were an enthusiastic group and anxious to have a positive impact on the operation of their respective Chapters. For these new Chapter Officers and all of the new committee Chairs, Board members, and officers at the national level, these first few months in office are very important for having a successful year.

You may actually have more free time now than you will have in the coming months. It’s a good opportunity to do some creative work by making contacts with other new officers and committee members, as well as maintaining contacts with former leaders. You might want to initiate

Cyclessmall group interactions to define a few key goals that you will passionately pursue. In doing this, it’s good to have some personal goals, but your main emphasis should be on the long-term goals of your organization or committee. In all of your pursuits, strive for excellence and integrity.

One of the biggest issues discussed at the Chapter Roundtable—and something that is a significant issue for all ACI committees and boards—is how to get enthusiastic participation from your membership. For the group attending the Roundtable, this seemed to be a particular concern with respect to getting younger members excited about what is happening within their chapters. Many chapters held golf outings or other social events, like attending a professional ballgame, to create excitement and camaraderie among their members.

To create interest among the younger members at the national level, ACI has put together the Student and Young Professional Activities Committee. There is plenty of enthusiastic participation at those committee meetings and I believe it’s because those young people feel ownership for what the committee is doing and trying to achieve. Not surprisingly, that same rule applies to ACI activities and meetings at all levels. The most exciting committee meetings during ACI Conventions are those where there is time in the agenda for more open discussion between the committee members. In some cases, presentations are made or a brainstorming session is scheduled to generate discussion on what topics or committee documents the membership wants to develop over the next few years. If the members believe they have ownership in the future plans for the committee, they will be more passionate about their participation.

So, as many of you “graduate” into new leadership roles, be mindful to use your time and that of your colleagues wisely. Consider seeking more enthusiastic participation from your colleagues by giving them the opportunity to make real decisions and have an influence on where your particular committee or other governing body is going in the future.

James K. Wight

To learn more about our sustaining members, visit our Web site at www.concrete.org/members/mem_sustaining.htm

are the foundation of our success.

To provide additional exposure to ACI Sustaining Members, Concrete International includes a 1/3-page member profile and a listing of all Sustaining Member organizations. All Sustaining Members receive the 1/3-page profile section on a rotating basis.

Lafarge North America

Lehigh Cement Co.

Lithko Contracting, Inc.

Meadow Burke

W. R. Meadows, Inc.

Metromont Corporation

Mintz Levin

Municipal Testing

North S.Tarr Concrete Consulting PC

Operating Engineers Training Trust

Oztec Industries, Inc.

Pacific Structures

Penetron International Ltd.

PGESCo

Portland Cement Association

Precast/Prestressed Concrete Institute

Schmitt Technical Services, Inc.

Sika Corp.

S.K. Ghosh Associates, Inc.

STRUCTURAL

Structural Services, Inc.

Triad Engineering, Inc.

TWC Concrete Services

Urban Concrete Contractors Ltd.

Wacker Neuson

Westroc, Inc.

ACS Manufacturing Corporation

Advanced Construction Technology

Services

Ash Grove Cement Company

Ashford Formula

Baker Concrete Construction, Inc.

Barrier-1 Inc.

BASF Corporation

BCS

Buzzi Unicem USA

Cantera Concrete Company

CECO Concrete Construction

Changzhou Jianlian Reinforcing Bar

Conjunction Co., Ltd.

CHRySO, Inc.

Concrete Reinforcing Steel Institute

CTLGroup

Dayton Superior

The Euclid Chemical Co.

Fibercon International, Inc.

Future Tech Consultants

W.R. Grace & Co.

Headwaters Resources, Inc.

Holcim (US) Inc.

Keystone Structural Concrete, LLC

Kleinfelder

With a culture that thrives on challenges and takes pride in the success of its co-workers and clients, Baker has become an industry leader that goes beyond the expected. Whether it’s a power generation project, or one of the nation’s premier stadiums, Baker’s professional teams bring the same drive, enthusiasm, and innovative spirit to every project.

Headquartered in Ohio, and with 12 office locations that support work throughout the United States and beyond, Baker offers a full spectrum of concrete construction and related services, from preconstruction through completion.

Baker is in the business of creating structures and relationships that are built to last. In addition to superior workmanship delivered with an eye toward safety, quality, and efficiency, Baker offers clients a partnership based on integrity and trust. Delivering the highest caliber of performance, diverse expertise, and extensive capabilities, Baker’s clients can expect more with every project.

To learn more about Baker, please visit their Web site at www.bakerconcrete.com.

To learn more about our sustaining members, visit our Web site at www.concrete.org/members/mem_sustaining.htm

are the foundation of our success.

Schmitt Technical Services, Inc. embraces the challenge of each new project with tenacity, experience and dedication focused on finding a solution.

Through our newly defined Geological Services, Chemical Services and Petrographic Services Divisions we are better able to address your unique needs.

Our recently acquired field equipment and instrumentation allows us to do specialized field sampling and testing so we can help you define and troubleshoot construction materials and product problems and failures or explore for new raw materials and minerals resources. A recent expansion to our facility brings you access to our petrographic, wet chemistry, organic chemistry and chemical instrumentation laboratories for a full range of chemical testing and forensic services.

Our expert staff and cutting edge technology makes us the superior choice for chemical analysis of cements, concrete, masonry mortars, organic and inorganic additives, admixtures, and construction products.

At Schmitt Technical Services, Inc., we pride ourselves on our ability to detect your unique material concerns in the most effective way possible.

To learn more about Schmitt Technical Services, Inc., please visit their Web site at www.schmitt technicalservices.com or call 608-798-5650.

Meadow Burke is a premier manufacturer and distributor for the concrete construction industry. For more than seven decades, Meadow Burke has served architects, engineers and contractors with a superior line of concrete reinforcing products, concrete forming accessories, road and bridge products, and products for precast and tilt-up construction. Known for quality and reliability, Meadow Burke continues to focus on product diversification and new construction technologies to reduce labor costs and construction time. With excellent customer service and experienced engineering, Meadow Burke provides support and expertise for all your construction projects.

In 2006 Meadow Burke became a part of Oldcastle, Inc. and remains committed to meeting the needs of our customers.

To learn more about Meadow Burke, please visit their Web site at www.meadowburke.com or call 877-518-7665.

Municipal Testing is a special inspection agency, nondestructive testing, engineering firm, geotechnical firm and materials testing laboratory headquartered in Hicksville, NY, with offices in Florida and several eastern states. Our primary focus is the inspection, NDT, and testing of building construction and transportation materials for major construction, R&D, and new technologies. Established in 1960, Municipal Testing is one of the oldest accredited inspection agencies and construction laboratories in the northeast.

Accreditations include ASTM C1077/E329, C1093/E329, D3666/E329, C1093, and D3740/E329. In Florida we are authorized/certified as an Engineering Firm and Geotechnical Business. Our engineers, inspectors, and technicians are certified by nationally recognized certification agencies.

Municipal Testing is proud to be involved in the technician/inspector training and certification programs as an ACI Sponsoring Group, in technical writing and committee work with the American Concrete Institute (ACl) and ASTM International (ASTM), and in shaping new building code revisions to improve the quality of construction for the industry.

We offer our clients a vast institu-tional memory and forensic technical expertise in engineering, geotechnical, inspection, testing, and construction for all sizes of projects and types.

To learn more about Municipal Testing, please visit their Web site at www.mtllab.net or call 631-761-5555.


NewsEstablishing a Private Sector Strategy for Disaster Reduction

Major disasters triggered by natural hazards impact the lives and livelihoods of millions of people around the world, both in developed and developing countries. The associated economic and insured losses are rapidly rising in line with the frequency and severity of natural catastrophes. Disaster mitigation and management are central to a sustainable future. The Concrete Joint Sustainability Initiative (Concrete JSI) is among the organizations leading the worldwide effort to promote more resilient and durable communities.

Aris Papadopoulous, Chair of Concrete JSI and Chief Executive of Titan America, is also Chair of the Private Sector Advisory Group (PSAG) to the United Nations Secretariat for the International Strategy for Disaster Reduction (UNISDR). The PSAG is an invitation-only consultative assembly to UNISDR, but with the PSAG’s help, the UNISDR has created a mechanism to further engage the private sector in future disaster initiatives by creating a new division, the Disaster Risk Reduction Private Sector Partnership (DRR-PSP). DRR-PSP was created during the UN Global Platform for Disaster Risk Reduction in Geneva, Switzerland, in May 2011.

The DRR-PSP has five essential goals: • Promote and develop public-private partnerships; • Leverage private sector expertise and strengths; • Foster a collaborative exchange and dissemination of data; • Support national and local risk assessments; and • Support the development and strengthening of national

and local laws, regulations, policies, and programs.Companies are urged to participate in DRR-PSP because

involvement can lead to a wide set of benefits, including: • Protection of vulnerable people and communities.

The foundational reason for DRR engagement is a humanitarian one;

• Economic case. Studies show that the cost of prevention is significantly less than that of recovery, relief, and reconstruction;

• Business continuity. Disasters can disrupt or shut down business operations. Investment in reducing risk can result in greater continuity of company operations;

• Business opportunities. Engagement in disaster risk reduction can generate business opportunities;

• Insurance benefits. Investment in DRR infrastructure leads to a lower risk environment which, in turn, enables access to lower cost insurance products; and

• Staff motivation/retention. Engagement in disaster risk reduction can enhance staff motivation and retention.Officers of private businesses, trade organizations, and

government-owned business enterprises are encouraged to sign and submit the DRR-PSP and a Membership Application and its Statement of Commitment by the Private Sector for Disaster Prevention, Resilience, and Risk Reduction, both found at www.unisdr.org/partners/private-sector.

For more on the activities of the DRR-PSP, visit www.preventionweb.net/english/professional/networks/public/ppp-drr/. For more information on Concrete JSI, visit www.sustainableconcrete.org.

Updated Specification for Encapsulated Tendons

The Post-Tensioning Institute (PTI) has announced a new specification update approved by the PTI Board of Directors and the Technical Advisory Board. Addendum #3 to PTI M10.2-00, “Specification for Unbonded Single Strand Tendons,” requires the following:

All unbonded single-strand post-tensioning tendons used for structures designed in accordance with the Building Code Requirements for Structural Concrete (ACI 318) must be encapsulated. The encapsulation of the tendons shall be in accordance with the material requirements for aggressive environments in the PTI “Specification for Unbonded Single-Strand Tendons” (PTI M10.2-00).

The intent is to augment the durability of the post-tensioning systems used for all applications governed by ACI 318. Encapsulated systems provide additional protection of the prestressing steel regardless of location of the structure or exposure to moisture intrusion from any source.

Addendum #3 to PTI M10.2-00, “Specification for Unbonded Single Strand Tendons,” is available for free download on PTI’s Web site, www.post-tensioning.org/uploads/addendum3.pdf.

ASCC’s New Officers and DirectorsMike Poppoff, Poppoff, Inc., Moxie, WA, was elected

First Vice President of the American Society of Concrete Contractors (ASCC), for 2012-2013. Scott Anderson, Houston, TX; Chris Plue, San Mateo, CA; and Thomas Zinchiak, Woodbine, MD, were re-elected Vice Presidents. Keith Wayne, Kannapolis, NC, was elected Secretary/Treasurer. Jack Cooney, Ft. Myers, FL, and Aaron Long, Rocky Mount, VA, were elected as new Directors. Robert Dalrymple, Valley View, OH; Peter Emmons, Hanover, MD; Shawn McMahon, Irving, TX; and John Ylinen, Tempe, AZ, were re-elected as Directors.

The Decorative Concrete Council (DCC), a specialty council of the ASCC, elected Chris Klemaske, T.B. Penick & Sons, Inc., San Diego, CA, as Council Director. Paul Schneider, Cincinnati, OH, was re-elected Secretary/Treasurer.


News

Nick Adams, Cleveland, OH; John Belarde, Woodinville, WA; Clark Branum, Marysville, WA; and Tim Fischer, Louisville, CO, were elected as new members of the council. Ray Brooks, Sioux Falls, SD; Clyde Cobb, West Columbia, SC; Marshall Hoskins, Columbia, SC; Dionne Hutchings Ojeda, Dallas, TX; Gregory Hyde Hryniewicz, Annapolis, MD; Byron Klemaske II, San Diego, CA; Jim Mullins, Naperville, IL; Joe Nasvik, Addison, IL; Kevin Percy, Walpole, MA; Rob Sousa, East Providence, RI; and Wes Vollmer, San Antonio, TX, were re-elected as Directors of the DCC Advisory Council.

The ASCC Safety and Risk Management Council re-elected Steve Pereira, Professional Safety Associates, Denham Springs, LA, as Council Director and Scott Winkler, Hamilton, OH, as Secretary/Treasurer. Mike Dawson, Detroit, MI; Al Padelford, Alpharetta, GA; and Ray Raffin, Chicago, IL, were elected as new Directors. Helen Prince, Dallas, TX, and E. Byron Spencer, Lombard, IL, were re-elected as Directors.

Mike Ferguson, Multiquip, Inc., Carson, CA, is the new Council Director of the Manufacturer’s Advisory Council and Jeremy Clark, Chicago, IL, has been elected as the new Secretary/Treasurer. Craig Dahlgren, St. Louis, MO, and Tim Lickel, Sussex, WI, were elected as new members of the Council and Wayne Allen, Sturtevant, WI; Jim Hughes, Fair Lawn, NJ; and Doug Rhiel, Mt. Pleasant, SC, were re-elected as Directors.

Speakers Named for CEO Forum

Humanitarian, Navy SEAL, and author Eric Greitens is the Keynote and Opening Session speaker for the ASCC’s CEO Forum, July 26-29, 2012, at Coeur d’Alene Resort, Coeur

d’Alene, ID. Greitens has authored two books: Strength and Compassion, an award-winning book of photographs and essays, and The Heart and the Fist, about his education as a humanitarian and his journey to become a Navy SEAL. He was deployed four times—to Iraq, Afghanistan, the Horn of Africa, and Southeast Asia. He continues to serve in the reserves with the U.S. Special Operations Command.

The CEO Forum will also include seminars, roundtable discussions, a golf tournament, and numerous other networking opportunities. Other speakers are Anirban Basu, Chief Economist for the Associated Builders and Contractors; Anthony Huey, Reputation Management Associates; and Vic Coppola, PI Associates.

For more information or to register, visit www.ascconline.org or tele-phone (866) 788-2722.

ASA Officers ElectedJoe Hutter, King

Packaged Materials Company, has been elected by the American Shotcrete Association (ASA) membership to a 1-year term as President. Hutter is the Vice President of Sales at King Packaged Materials Company, Burlington, ON, Canada. He has more than 20 years of experience in the cement/shotcrete industry. Hutter is also the Chair of ASA’s Marketing Committee.

The ASA membership has also elected several other individuals to leadership roles in the association. Elected to 1-year terms are Vice-President Michael Cotter, Consultant; Secretary Charles Hanskat, Consultant; and Treasurer Ted Sofis, Sofis Company, Inc. Hutter, Cotter, Hanskat, and Sofis, plus immediate Past President

hutter


News

Patrick Bridger, Allentown Shotcrete Technology, Inc., will serve as ASA’s 2012 Executive Committee.

Three individuals were elected to 3-year terms as ASA Directors. The three Directors are Marcus von der Hofen, Coastal Gunite Construction Company; Lihe (John) Zhang, LZhang Consulting & Testing Ltd.; and Scott Rand, King Packaged Materials Company.

The election of Charles Hanskat to the Secretary position created a vacancy on the 1 year remaining on his term as Director. Following ASA bylaws, the ASA Board has appointed Oscar Duckworth, Valley Concrete Services, to fill the remainder of the term.

These individuals will join with five previously elected Directors (Dan Millette, The Euclid Chemical Company; Ryan Poole, DOMTEC International, LLC; Tom Norman, Airplaco Equipment Company; William Drakeley, Drakeley Industries; and Ray Schallom III, RCS Consulting & Construction Company) and the ASA Executive Committee to form the 14-member ASA Board of Direction for 2012.

CSDA Celebrates 40 Years This year marks the 40th anniversary of the Concrete

Sawing & Drilling Association (CSDA), and the future is likely to be as event-filled as its past 40 years have been. Formed in 1972 with just 18 charter members, today CSDA has almost 500 member companies from around the world and continues its mission to promote the selection of professional sawing and drilling contractors and their methods. Membership includes contractors, manufacturers, distributors, and affiliate companies in the concrete sawing and drilling industry.

“CSDA has made tremendous progress in its first 40 years and is positioned to build on that success for an even brighter future,” said CSDA Executive Director Patrick O’Brien.

The knowledge and experience of its members has enabled CSDA to produce 33 industry Specifications, Standards, Tolerances, and Best Practice documents. In addition, the association has created the CSDA Safety Manual, a 208-page comprehensive safety document, and has 100 Toolbox Safety Tips in circulation to increase hazard awareness to its membership and enhance operator safety.

CSDA has developed an extensive range of training options to equip sawing and drilling operators with the necessary skills to handle any concrete-cutting job. The association launched Cutting Edge, an entry-level course, in 1993; close to 800 students have graduated from this class. Several hands-on classes followed for major cutting disciplines, and in 1996, the association introduced the CSDA Operator Certification program for skilled and experienced students. Training has also shifted from the classroom to the home or office. The CSDA Online Training program was launched in 2007. The program boasts 29 online classes, which have been completed by over 1700 students.

Visit www.csda.org for more information.

World Engineering Prize Opens for Nominations

The international engineering community can nominate their peers for the inaugural Queen Elizabeth Prize for Engineering, created to celebrate the achievements of today’s engineers. The Royal Academy of Engineering is

Long-time ACI Staffer RetiresAfter nearly 43 years with ACI, Terry R. Scates retired as Supervisor,

Warehouse Operations, effective July 6, 2012. Since joining the staff in October 1969, Terry has overseen the mailroom operations, handled bulk shipments, and followed up on publication orders. He also tracked the errata for ACI documents and publications. It’s no small task to oversee ACI’s shipping/receiving and mail center operation—roughly 500 packages (not including mail) either leave or are received by ACI each week. In addition to maintaining equipment, he took daily and annual inventory to ensure supplies were on the shelves and publications in stock. ACI commends Terry for his long-time dedication and thanks him for his years of service. His colleagues on staff wish him the best in retirement.

Scates


accepting nominations for the prize, which will award £1 million to the winning engineer or group of engineers responsible for the world’s greatest modern engineering advancement that has had a demonstrable benefit for humanity, as determined by the judging panel.

Nominations are open until September 14, 2012. Details on how to submit a nomination can be found at www.qeprize.org. The winner will be announced at a ceremony in spring 2013.

An initial endowment has been established with support from BAE Systems, BG Group, BP, GlaxoSmithKline, Jaguar Land Rover, National Grid, Shell, Siemens, Sony, Tata Consultancy Services, Tata Steel, and Toshiba. The prize will be awarded biennially.

In MemoriamWilliam G. Godden, Professor

Emeritus, University of California-Berkeley, Berkeley, CA, passed away on April 6, 2012, in Bellingham, WA. He was 88. Godden joined the Structural Engineering, Mechanics and Materials faculty at UC-Berkeley in 1964 and he retired from active teaching in 1991. His legacy to teaching and engineering includes the Godden Structural Engineering Slide Library that has been archived in the National Information Service for Earthquake Engineering.

Helmut Krawinkler, John A. Blume Professor Emeritus of Engineering at Stanford University, Stanford, CA, died April 16, 2012. He was 72. He joined the faculty of the Department of Civil and Environmental Engineering in 1973 and “retired” to emeritus status in 2007. He is best known for his research contributions in perfor-mance-based earthquake engineering, which were recognized most recently through his election to the National Academy of Engineering.

News

ErrataThe May 2012 issue cover image

should have been credited to photo-grapher D.C. Goings.

In the June 2012 issue, there was a misspelling of Longtime 25-Year Member Andrew W. Taylor’s name.

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14 APRIl 2012 Concrete international

October 21-25, 2012 • Sheraton Centre • Toronto, ON, Canadawww.aciconvention.org

ACI Fall 2012ConventionForming Our Future

Whether it is increasing the strength and life span of a structure or reducing a project’s environmental impact, the concrete industry is consistently developing techniques and technologies that shape the future of the world we live in. When attending technical sessions at the ACI Fall 2012 Convention, you will learn how these developments are “Forming our Future” while earning valuable Professional Development Hours (PDHs).

Sustainability

• Concrete Sustainability Forum and Panel Discussion (Fifth Anniversary)

• Teaching Sustainability to Current and Future Engineers

• The Economics, Performance, and Sustainability of Internally Cured Concrete, Parts 1-3

• Sustainability of Concrete Pavements

• Perspectives on Service Life

Construction

• Contractors’ Day Session—Concrete’s Contribution to Infrastructure, Parts 1 of 3

• Contractors’ Day Session—Forming our Future- Innovations and Advancements in Concrete Forming, Parts 2 & 3

• Site Casting New Form: Inspiring Function to Respond

Binders

• Natural Pozzolans—Renaissance of a Proven Technology, Parts 1 and 2

• Shrinkage Compensating Concrete—Past, Present, and Future, Parts 1 and 2

• Portland-Limestone Cements: A Technology to Improve the Sustainability of Concrete

Design

• The Art of Designing Ductile Concrete in the Past 50 Years: The Impact of the PCA Book and Mete A. Sozen, Parts 1 and 2

• Forming a Framework for Performance Based Seismic Design of Concrete Bridges, Parts 1 and 2

• Analysis and Design Issues in Liquid Containing Structures, Parts 1-3

• Contrasting Approaches to Blast-Resistant Design for Differing Contexts

• Blast Testing for Structural Performance Verification

Concrete international APRIl 2012 15

ConventionForming Our Future

Earn Over 25

PDHsReinforced Concrete

• Reinforced Concrete Columns with High Strength Concrete & Steel Reinforcement, Parts 1 and 2

• Applications of Acoustic Emission for Reinforced Concrete, Parts 1 and 2

• Means and Methods of Evaluating Reinforced Concrete Structures

• Fiber Reinforced Concrete for Sustainable Structures

Recent Advances, Research, and More

• Emerging Technologies in the Concrete Industry

• Machine Foundations, Parts 1 and 2

• Research in Progress, Parts 1 and 2

• UHPC—Experience and Developments, Parts 1 and 2

• Advancements in the Use of Building Information Modeling (BIM) Systems, Parts 1 and 2

• Emerging Technologies, Parts 1 and 2

• Joint KCI-ACI Session: International-Level Research, Practice and Partnerships, Parts 1-3

• Hot Topic Session

• Placement of Epoxy Grouts in an Industrial Environment

• Using Social Media to Boost Brand/Company Awareness

For detailed session descriptions and updates, visit www.aciconvention.org.

Scan QR Code for Mobile Convention Site


ACI Hellas ChapterThe ACI Hellas Chapter organized a successful seminar

on concrete technology at the premises of the Association of Civil Engineers of Greece in September 2011. The seminar was directed to the civil engineers working at the General Directorate of Quality for the Projects of the Ministry of Public Works. Basic and advanced topics on concrete and reinforcing steel were covered during the 1-week seminar, which was aimed at improving the quality and reducing the cost of infrastructure projects.

ACI Dakota Chapter The ACI Dakota Chapter hosted the 48th Annual

Concrete Conference, based on the theme of “How to Get the Concrete You Need,” at the South Dakota School of Mines & Technology (SDSMT), Rapid City, SD, on March 2, 2012. Presenters included Luke Snell on “How to Get the Concrete You Need Approved,” “Acceptance for the Con-crete You Need,” and “Effects of Defects: How Cylinders Go Bad”; Tarek Khan on “What Can Admixtures Do for Your Concrete?” “Cold Weather Concreting,” and “Hot Weather Concreting”; Michael Schneider on “News from ACI”; and Jody Titze on “Updates from the South Dakota Ready Mixed Concrete Association.”

Excellent and Outstanding Chapter Awards

Annually, the excellent and outstanding chapters of ACI are determined by a point rating scale based on activity during the preceding year. For 2011, there were 28 chapters that qualified for awards. The winning chapters were recognized during the Opening Session and Awards Program at the ACI Spring 2012 Convention in Dallas, TX.

ACI chapters achieving excellent honors—the highest rating—were: Arizona, Central & Southern Mexico, Florida Suncoast, Georgia, Greater Miami Valley, India, Iran, Kansas, Missouri, Nebraska, New Jersey, New Mexico, Northeast Texas, Peru, San Diego International, and Southern California.

The ACI chapters rated as outstanding include Carolinas, Concrete Industry Board New York City, Greater Michigan, Indiana, Intermountain, Las Vegas, Louisiana, Northeast Mexico, Northern California and Western Nevada, Ontario, Pittsburgh Area, and San Antonio.

For more information on the awards criteria, visit www.concrete.org/chapters/chap.htm.

Chapter Representatives Gather in Phoenix

The 81st ACI Chapter Officer Training and Round-table Meeting was held April 23-24, 2012, in Phoenix,

Participants at the ACI hellas Chapter seminar on concrete technology

At the 48th Annual Concrete Conference, from left: M.R. hansen, SDSMT; Tarek Khan, BASF Admixtures, Inc.; Jody Titze, South Dakota Ready Mixed Concrete Association; luke Snell, Western Technologies, Inc.; Michael Schneider, Baker Concrete Construction; and Molly Gribb, SDSMT

Chapter

Reports


AZ. Representatives from 15 ACI chapters, ACI officers, and ACI staff exchanged information on addressing the challenges of improving chapter operations. ACI Presi-dent Jim Wight welcomed the participants and spoke about new educational programs available from ACI for chapter use. The roundtable was moderated by ACI Chapter Activities Committee Chair Dawn Miller, Executive Director of the ACI Las Vegas Chapter. The meeting included presentations by Chair Miller; Ron Burg, ACI Executive Vice President; John Conn, ACI Manager, Certification Operations and Chapter Activi-ties; and Renee Lewis, ACI Director, Publishing and Event Services.

Chapter representatives who attended were: Arizona Chapter, Angelo Trujillo, Jim Rogers, and Jason Straka; Carolinas Chapter, Kenny Johnson and Wilson Taylor; Central Texas Chapter, Amanda Vann and Gerald Lankes; Dakota Chapter, Damon Fick; Kansas Chapter, Heather McLeod; Las Vegas Chapter, Andrea Scott and Mitch Englestead; Louisiana Chapter, Gavin Gillen and Mark Cheek; Maryland Chapter, Mindy Green; Mid-South Chapter, Harry Lee James; Northeast Texas Chapter, Bobby Ray; Northern California and Western Nevada Chapter, Kelly Idiart; Rocky Mountain Chapter, Matthew Best; San Antonio Chapter, Rick Wells and Chris DeGroff; Southern California Chapter, Ed Kripavicius; and San Diego Chapter, Quinn McGuire and Heather Caya (Caya repre-sented both the San Diego Chapter and the Southern California Chapter).

Topics discussed included membership recruitment and retention; popular meeting topics and speakers; chapter governance; student and academic relations, including scholarship programs; and effective communication with members and the construction community. While chapters face many common challenges, the unique character of the local concrete communities influences the way chapters operate. A common theme that emerged from the discus-sions was the benefit of collaborating with other industry groups and each other.

The first ACI Chapter Officer Training and Roundtable Meeting was held in Seattle, WA, in 1972. Since that first event, roundtables have been held in the United States, Canada, and several foreign countries. The fall 2012 Chapter Officer Training and Roundtable Meeting is scheduled for September 10-11, 2012, in Kansas City, MO. An International Chapter Officer Training and Round-table Meeting is scheduled for September 16-17, 2012, in Cartagena, Colombia.

For more information, contact Diane Pociask, ACI Chapter Coordinator, at (248) 848-3831 or [email protected].

Attendees at the ACI Chapter Officer Training and Roundtable Meeting in Phoenix, AZ

Chapter Reports


The following ACI documents will soon be available:

“Report on the Use of Raw or Processed Natural Pozzolans In Concrete (ACI 232.1R-12)”

Reported by ACI Committee 232, Fly Ash and Natural Pozzolans in Concrete

Karthik H. Obla,* Chair; Robert E. Neal† and Michael D. A. Thomas,* Vice Chairs; Bruce W. Ramme,* Secretary; Thomas H. Adams, James C. Blankenship, Julie K. Buffen-barger, Ramon L. Carrasquillo, Barry A. Descheneaux, Jonathan E. Dongell,* Thomas M. Greene, Harvey H. Haynes, James K. Hicks, R. Doug Hooton,* Morris Huffman, James S. Jensen, Tilghman H. Keiper, Steven H. Kosmatka, William J. Lyons III, Adrian Marc Nacamuli, Tarun R. Naik, Gerald C. Plunk, Steve Ratchye, Michael D. Serra, Ava Shypula, Boris Y. Stein, Lawrence L. Sutter,* Oscar Tavares, Paul J. Tikalsky,* and Orville R. Werner II.*

Consulting Members: Mark A. Bury, James E. Cook, Dean M. Golden, William Halczak, G. Terry Harris Sr., Jan R. Prusinski, Harry C. Roof, and Della M. Roy.*Subcommittee member for this report†Subcommittee Chair for this report

Abstract: This report reviews the use of raw or processed natural pozzolans in concrete and provides an overview of the properties of natural pozzolans and their use in the production of hydraulic-cement concrete. Long before the invention of portland cement, natural pozzolans mixed with lime were used to strengthen concrete and mortar. Today, they can be used to enhance the properties of fresh and hardened concrete and may provide economic value in some cases.

“Guide to Cast-in-Place Architectural Concrete Practice (ACI 303R-12)”

Reported by ACI Committee 303, Architectural Cast-In-Place Concrete

Chris A. Forster, Chair; Keith Ahal, George F. Baty, Eugene H. Boeke Jr., Daniel P. Dorfmueller, Thomas J. Grisinger, Gardner P. Horst, James M. Shilstone Jr., Michael S. Smith, David M. Suchorski, Claude B. Trusty Jr., and Gregory R. Wagner.The committee would like to thank the late Louis Tallarico for his contribution to this guide.

Abstract: This guide presents recommendations for producing cast-in-place architectural concrete. The importance of specified materials, forming, concrete placement, curing, additional treatment, inspection, and their effects on the appearance of the finished product are discussed. Architectural

concrete requires special construction techniques, materials, and requirements that are unique to each project.

“Guide for the Design and Construction of Durable Concrete Parking Structures (ACI 362.1R-12)”

Reported by ACI Committee 362, Parking StructuresKeith W. Jacobson,* Chair; Erich L. Martz, Secretary;

Ralph T. Brown, Girdhari L. Chhabra, Ned M. Cleland, Thomas J. D’Arcy,* James P. Donnelly, Thomas J. Downs,* Boris Dragunsky, Gregory F. Force, Harry A. Gleich, Mohammad Iqbal, Howard R. May,* Martin B. Mikula, David C. Monroe, Thomas E. Nehil, Carl A. Peterson,* Kurt Wagner, H. Carl Walker,* and Thomas G. Weil.*Chapter authors and members of the draft review committee

Abstract: This guide presents design and construction criteria used to improve the durability of concrete parking structures. Emphasis is placed on key design criteria unique to parking structures, including structural systems, materials, structural design, durability, and construction. Also covered are cast-in-place nonprestressed concrete, cast-in-place post-tensioned concrete, and precast/prestressed concrete structural systems for use in parking structures.

“Code Requirements for Design and Construction of Concrete Structures for the Containment of Refrigerated Liquefied Gases (ACI 376-11) and Commentary”

Reported by ACI Committee 376, Concrete Structures for Refrigerated Liquefied Gas Containment

Neven Krstulovic-Opara, Chair; Piotr D. Moncarz, Secretary; Junius Allen, Dale Berner, Mike S. Brannan, Hamish Douglas, Charles S. Hanskat, Humayun Hashmi, Alan D. Hatfield, Kare Hjorteset, George C. Hoff, Richard A. Hoffmann, John Holleyoak, Joseph Hoptay, Thomas R. Howe, Dajiu Jiang, Jameel U. Khalifa, Nicholas A. Legatos, Praveen K. Malhotra, Keith A. Mash, Stephen Meier, Robert W. Nussmeier, Rolf P. Pawski, Ramanujam S. Rajan, William E. Rushing Jr., Robert W. Sward, Eric S. Thompson, and Sheng-Chi Wu.

Consulting Members: Robert Arvedlund, James P. Lewis, and Terry Turpin.

Abstract: ACI Committee 376 was formed and subsequently ACI 376.11 was drafted in response to a request from the National Fire Protection Association (NFPA) Technical Committee 59A on liquefied natural gas (LNG). That committee is responsible for NFPA 59A, which is an internationally recognized standard governing the production,

ACI Committee Document

Abstracts


storage, and handling of LNG at an operating temperature of –270°F. The commentary is not intended to provide a complete historical background concerning development of the code, nor is it intended to provide a detailed summary of the studies and research data reviewed by the committee in formulating its provisions. ACI 376 may be used as a part of a legally adopted code and, as such, must differ in form and substance from documents that provide detailed specifications, recommended practice, complete design procedures, or design aids.

“Specification for Latex-Modified Concrete Overlays (ACI 548.4-11)”

Reported by ACI Committee 548, Polymers and Adhesives for Concrete

Michael S. Stenko, Chair; Herschel H. Allen III, Milton D. Anderson, John J. Bartholomew, Constantin Bodea, James T. Dikeou, Garth J. Fallis, David W. Fowler, Robert W. Gaul, Albert O. Kaeding, John R. Milliron, Bradley Nemunaitis, Richard C. Prusinski, Mahmoud M.

Reda Taha, John R. Robinson, Donald A. Schmidt, Qizhong Sheng, Joe Solomon, Michael M. Sprinkel, Donald P. Tragianese, Cumaraswamy Vipulanandan, Wafeek S. Wahby, Harold H. Weber Jr., David White, and David P. Whitney.

Consulting Members: Lu Anqi, Zhi-Yuan Chen, Lech Czarnecki, Harold (Dan) R. Edwards, Larry J. Farrell, Jack J. Fontana, Deon Kruger, William Lee, Henry N. Marsh Jr., Peter Mendis, Yoshihiko Ohama, Jerzy Pietrzykowski, and Meyer Steinberg.Special acknowledgment to Mahmoud M. Reda Taha for his contribution to this specification.

Abstract: This Reference Specification covers styrene-butadiene latex-modified concrete as an overlay on concrete bridge decks and other structures. It applies to both new construction and rehabilitation of existing structures. It includes certification requirements of the latex products, storage, handling, surface preparation, mixing, application, and limitations.

Document Abstracts

eLearning

Now Available:Controlled Low-Strength Material (CLSM) Fundamentals0.2 CEU (2 PDH), $80 nonmembers, $64 membersCLSM (also known as flowable fill) is a self-consolidating, cementitious material used primarily as backfill in place of compacted fill. This course covers the basics of CLSM technology, including materials used to produce CLSM; plastic and in-service properties; proportioning, mixing, transporting, and placing; quality control; and common applications. Concrete Sustainability: Basics0.15 CEU (1.5 PDH), $75 nonmembers, $60 membersThis course provides an introduction to the subject of sustainability, with a special emphasis on the concrete industry. Participants will study common definitions of sustainability, identify “greenwashing” in the market-place, understand the three pillars of sustainability, and identify strategies for the integration of concrete in sustainable development.

Concrete Sustainability: Incorporating Environmental, Social, and Economic Aspects0.15 CEU (1.5 PDH), $75 nonmembers, $60 membersThis course provides an in-depth study of topics related to the environmental, social, and economic impacts of using concrete in sustainable development. Topics include the use of industrial by-products, thermal mass, storm-water management, longevity, and heat-island effect, among several others.

Also available: •ConcreteBasics•ConcreteFundamentals

•Concrete Field Testing Grade I Certification Training•ConcreteStrengthTestingTechnicianTraining

Visit our Web site: ACIeLearning.org


On the

MoveThe Portland Cement Association (PCA) named

Gregory M. Scott Senior Vice President of Government Affairs. He will head PCA’s office in Washington, DC, and represent the association and its members before Congress and the White House. He has a record of experience and accomplishments in trade association leadership and legislative campaigns on federal transportation and environmental and energy issues. Most recently, he served as Executive Vice President for the National Petrochemical and Refiners Association, where he initiated a significant expansion of the association’s public policy advocacy efforts. Scott received his BA from Colorado College, Colorado Springs, CO, and his JD from the American University’s Washington College of Law, Washington, DC.

ACI member Mark Haworth was appointed as President of Blastrac, NA. Haworth joined Blastrac in Oklahoma City, OK, in 2007, and in that time has been instrumental in guiding the company’s growth and profitability. He has over 23 years of manufacturing experience and received his BS in electrical engineering from Pittsburg State University, Pittsburg, KS.

James F. Lane has joined CTLGroup as the firm’s Director of Structural & Transportation Laboratory Services. He will be responsible for the technical and business operations of CTLGroup’s structural and transportation laboratory facility. Lane has over 20 years of consulting experience in materials engineering and failure analysis, with a focus on metallurgy and corrosion, and

was a principal engineer with a metallurgical engineering consulting group. He received his MS of materials science and engineering and his BS of materials engineering from the Georgia Institute of Technology, Atlanta, GA, and is a licensed professional engineer in five states.

Vilas Mujumdar, FACI, was selected by the American Association of Engineering Societies to be the U.S. representative to the World Federation of Engineering Organizations (WFEO), representing nearly 800,000 U.S. engineers in all engineering disciplines. His 4-year term began October 1, 2011. He was also elected to serve on the WFEO’s Executive Council, in addition to his positions in other WFEO groups dealing with international activities and disaster risk management. He has held various positions across the U.S. dealing with seismic engineering. He currently serves on ACI Committees 335, Composite and

Hybrid Structures; 374, Performance-Based Seismic Design of Concrete Buildings; and Joint ACI-ASCE Committee 550, Precast Concrete Structures; and is a private consultant based in Vienna, VA.

Honors and AwardsThe book Design of Steel Structures, authored by ACI

member Narayanan Subramanian, received the Association of Consulting Civil Engineers-India (ACCE-I) Nagadi Award for the best book in civil engineering published in 2011. The book was recognized for its educational value to both students and those with experience in the field. Subramanian has over 30 years of experience in the industry, including consulting, research, and instruction, and has authored more than 200 technical papers and more than 20 books.

ACI member Kilah Engelke received the second Women of Distinction award from the Women in Concrete Alliance (WICA). Engelke has been a concrete finisher with the Operative Plasterers’ and Cement Masons’ International Association (OPCMIA) for the past 11 years, and was hired in October 2011 as the first apprenticeship coordinator for Milwaukee OPCMIA Local 599. Prior to completing her apprenticeship as a finisher, she spent 3 years as a

laborer on a slipform paving crew. She received the award due to the respect she has garnered from her crew as a result of her passion for concrete and her job.

The American Society of Civil Engineers (ASCE) gave out its annual Outstanding Projects and Leaders (OPAL) Awards. Established in 1999, the OPAL Awards recognize and honor outstanding civil engineering leaders whose lifetime accomplishments and achievements have made significant differences in one of five categories. In each category, the awardees were: Construction, Robert L. Bowen, Bowen Engineering Corporation; Design, ACI member Michael J. Abrahams, Parsons Brinckerhoff, Inc.; Education, ACI member Clifford Schexnayder, Arizona State University; Government, Francis J. Lombardi, the Port Authority of New York and New Jersey; and Manage-ment, Thomas R. Warne, Tom Warne and Associates, LLC.

lane Engelke

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Ash Grove Cement Plants ISO CertifiedAsh Grove Cement Co. became the first domestic

cement manufacturer to have all of its manufacturing facilities receive ISO 14001 certification. Seven of the company’s eight facilities earned the designation in 2010, and the last plant earned it in December 2011. The certification, administered by the International Organization for Standardization (ISO), requires companies to adopt a rigorous, systematic environmental management system customized to the needs unique to its facilities and subject to continuous improvement. Once a program is implemented, certified third-party auditors conduct an audit to verify compliance with the ISO standards before certification is granted and follow up with annual assurance audits. Ash Grove’s plants are located in eight states across the U.S.

Concrete Countertop Institute Relocates Training

The Concrete Countertop Institute moved the location of its training facilities from North Carolina to the Chicago, IL, area. Classes will be held at the Concrete Countertop Supply by Fishstone facility in Elgin, IL. This provides a more central location for classes and has access to a major international airport. Students will have better access to new tools and materials and can work with a recommended vendor of the Concrete Countertop Institute. There will be no change in curriculum or instructors.

LINE-X Put to the Test on “Mythbusters”In an episode that aired November 2, 2011, the durability

of LINE-X Protective Coatings was tested to extremes on the Discovery Channel show “Mythbusters.” The Myth-busters crew tested LINE-X in three situations, and the coating withstood the abuse. A jacket sprayed with LINE-X protected the wearer from the teeth of a trained police dog. In simulated car accidents, the coating was shown to reduce damage upon impact. In the final test, concrete and wood walls were exposed to a C-4 explosion; the walls without protection were destroyed, while the walls receiving a coating of LINE-X emerged unscathed, minus a few burn marks.

Thermomass Achieves 4-Hour Fire Resistance Rating

Thermomass® announced that it successfully completed the ASTM E119 fire test. The fire test was conducted on a sandwich wall panel consisting of a 2 in. (50 mm) exterior wythe of concrete, a 2 in. insulation core, and a 5 in. (127 mm) interior wythe of concrete. The interior wythe was loaded to a 4000 lb/ft (5950 kg/m) gravity load and exposed to fire for 4 hours, with temperatures reaching 2000°F (1093°C). During the test, the temperature of the exterior wythe

increased by only 130°F (72°C), which is 50% of the allowed temperature increase per ASTM E119.

Gate Precast to Supply Fort Hood HospitalGate Precast Company has been selected by the Balfour

Beatty/McCarthy joint venture design-build team to provide a thermally efficient, preinsulated, brick-inlaid architectural precast concrete exterior wall system for the U.S. Army Corps of Engineers’ replacement hospital at Fort Hood in Texas. The blast-resistant panels will feature a layer of insulation between the building’s interior and exterior, preventing thermal bridging and helping reduce energy use. The panels are expected to be installed at the 940,000 ft2 (87,000 m2) facility beginning in December 2012.

South African Cement Industry Bolstered by Global Partnership

The Cement Sustainability Initiative (CSI) of the World Business Council for Sustainable Development and South Africa’s Association of Cementitious Material Producers (ACMP) have joined forces to drive sustainable development. This partnership will allow the South African cement industry to tap into global expertise and make it locally relevant, and the cooperative agreement ensures a two-way transfer of knowledge. The agreement also allows ACMP to shape its response to climate change and sustain-able development, as well as letting CSI expand its activities in Africa.

BASF Launches Center for Building Excellence

BASF launched their Center for Building Excellence, a venture for providing consulting services to the North American construction industry. Staffed by an interdisci-plinary team of building science professionals, architects, and energy specialists, services offered include consultation in evaluating building systems and recommending alternatives, determining opportunities for cost shifting to achieve affordable solutions, and training and education in building science.

Simpson Strong-Tie Expands Offerings Simpson Strong-Tie announced its entrance into the concrete repair, protection, and strengthening markets with the acquisitions of Fox Industries, Inc., and S&P Clever Reinforcement Company. Fox Industries manufactures a complete line of coatings, grouts, mortars, adhesives, sealers, sealants, membranes, and custom-manufactured fiberglass parts for a wide variety of industries. S&P Clever produces epoxy resins and fiber-reinforced polymer materials for concrete and asphalt reinforcement.

Industry

Focus


ACI Student Fellowships, Scholarships for 2012-2013Applications for next year can now be submitted

For the 2012-2013 academic year, the ACI Foundation has awarded six Student Fellowships, five Graduate Scholarships, and one Undergraduate Scholarship.

For a complete description of these awards, visit www.concrete.org, click on “Students,” and then “Fellowships/Scholarships.”

ACI Foundation Student Fellowships The ACI Foundation Student Fellowships are offered to

high-potential undergraduate and graduate students in engineering, construction management, and other appropriate curricula who are nominated by ACI member faculty. The purpose of the Student Fellowship Program is to identify, attract, and develop outstanding professionals for productive careers in the concrete field. During the academic year, each student will receive a $7000 ($10,000 for the Charles Pankow Foundation ACI Student Fellowship) educational stipend for tuition, residence, books, and materials; appropriate certificates, recognition, and publicity; paid travel expenses and attendance fees to two ACI conventions; assignment to an industry mentor; and an optional summer internship (internships are required to receive the ACI Baker Student Fellowship, ACI Elmer Baker Student Fellowship, Cagley ACI Student Fellowship, and Charles Pankow Foundation ACI Student Fellowship).

Fourteen finalists were chosen to attend the last portion of the application process—the interview with the Fellowship Selection Team—this past March at the ACI Spring 2012 Convention in Dallas, TX.

The awardees are:

ACI Baker Student Fellowship Cameron Murray attends the University of Arkansas,

Fayetteville, AR, and will finish his BS this fall. He is still deciding which graduate program he will attend during

the second semester of the award year. His short-term career goal is to begin working at a structural engineering consulting firm and earn his PE license. Murray would like to practice as a structural engineer, but there are many things he could see himself doing, including returning to school for his PhD. His Faculty Nominator was Micah Hale; Eric Musselman, Convention Guide.

ACI Elmer Baker Student Fellowship Ashley Bagley attends Arizona State University,

Phoenix, AZ, completing requirements for her BS in construction management with an emphasis of concrete industry management, along with her MS in construction management. Her career goals for the near future are to become a project manager for a concrete contractor and become a Chair of an ACI committee. Bagley’s long-term goal is to become President of a construction company. Her Faculty Nominator was Jim Rogers; Sheila Shideh, Convention Guide.

ACI BASF Construction Chemicals Student Fellowship Jake Wiggins is studying civil and structural engineering

at the University of Colorado at Denver, Denver, CO. His career goals include obtaining his professional engineering license; working for a premier consulting firm; and eventually starting his own consulting firm, while also instructing either university or technical classes. His Faculty Nominator was Stephan Durham; Jim Hanson, Convention Guide.

ACI Presidents’ FellowshipBenjamin Dymond is a PhD candidate in civil

engineering with a focus on concrete structures at the University of Minnesota, Minneapolis, MN. He plans to focus his long-term career efforts on teaching future engineers about concrete structures while engaging in


research at an academic or research institution. He is interested in researching how innovative reinforced concrete materials, such as self-consolidating concrete or recycled mixture components, are incorporated into design. As an academic professional, Dymond hopes to challenge the way young engineers think in the classroom and push them to make an impact on civil engineering. His Faculty Nominator was Carol Shield; Rita Madison, Convention Guide.

ACI Richard N. White Student Fellowship Dane Shaw is completing his MS in civil engineering

with a structural emphasis at Missouri University of Science and Technology, Rolla, MO. He hopes to attain a position as a structural engineer in the precast industry and focus on bridge design. After many years in practice and successful completion of his PE or SE, Shaw plans on partnering with other colleagues to open a small-scale consulting firm. His Faculty Nominator was John Kevern; Larry Taber, Convention Guide.

Charles Pankow Foundation ACI Student Fellowship Brittany Schuel attends Lawrence Technological

University, Southfield, MI, and is working on her MS in civil engineering with a concentration in structural engineering. Her long-term career objectives include becoming a licensed PE and SE and joining a design firm to gain both design and construction experience with a focus in either bridge or tall building design. Schuel looks forward to continually expanding her knowledge through everyday work experiences and staying active in the engineering community. Her Faculty Nominator was Elin Jensen; Michelle Wilson, Convention Guide.

ACI Foundation Graduate ScholarshipsFunded primarily through donations, these scholarships

are offered to high-potential, full-time first- or second-year (after bachelor’s degree) graduate students during the entire scholarship year. During the academic year, each student will receive a $3000 educational stipend for tuition, residence, books, and materials and appropriate certificates, recognition, and publicity. Recipients of the 2012-2013 ACI Foundation Graduate Scholarships are: • ACI Bertold E. Weinberg Scholarship: Kyle Dunning,

University of Missouri-Kansas City, Kansas City, MO. He will enroll in the graduate structures program at the University of Texas at Austin, Austin, TX, for his MS in civil engineering. He plans to find a position with a structural engineering firm, designing concrete structures.

• ACI Katharine & Bryant Mather Scholarship: Alyson Dean, University of New Brunswick, Fredericton, NB, Canada. She is pursuing her MS in civil engineering with an emphasis on materials. After completing her

Murray Bagley Wiggins Dymond Shaw Schuel

ACI’s Online Career Center brings together great job opportunities and great candidates.

This job search engine is specifically targeted to the con-crete industry.

• Easy online job management• Resume searching access• Company awareness • FREE Student Internships

Don’t miss this unique opportunity to be seen by an exclusive audience of the industry’s best and brightest! Visit www.concrete.org.

ACI’s Career Center


Dunning Dean Cruz Kulesa Banker-hix Campbell

master’s and PhD degrees, Dean eventually hopes to work in academia.

• ACI Scholarship: Mariana Cruz, University of Delaware, Newark, DE. She plans to finish her MS in civil engineering with a concentration in structural engineering by Spring 2013. Cruz hopes to find a position with a structural engineering firm working in building design or rehabilitation. In the future, she may eventually pursue her PhD in structural engineering and become a professor.

• ACI Schwing America Scholarship: Anthony Thomas Kulesa, South Dakota School of Mines and Technology, Rapid City, SD. He is pursuing his MS in civil engineering with an emphasis on structures. His plans to practice structural engineering with Burns & McDonnell or possibly continue in academia.

• Kumar Mehta Scholarship: Wyatt Banker-Hix, California Polytechnic State University, San Luis Obispo, CA. After receiving his MS in civil/environmental engineering, his career goal is to specialize in public works projects and design water/wastewater treatment plants.

ACI Foundation Richard D. Stehly Memorial Scholarship

In addition, Blake Campbell is the recipient of the ACI Foundation Richard D. Stehly Memorial Scholarship. He is a senior in the Civil and Environmental Engineering program at Villanova University, Villanova, PA, focusing on structural engineering and foundation design. Following graduation, he hopes to pursue a graduate degree in the field of civil engineering with the expectation of starting a career in the concrete industry.

Applications Now Being Accepted Applications for ACI Foundation Student Fellowships

and Graduate and Undergraduate Scholarships for the 2013-2014 academic year are now being accepted. To nominate a student for the ACI Foundation Student Fellowship Program, submit a nomination form, which is available online at www.concrete.org/STUDENTS/st_fellowships.htm.

Only students nominated by faculty members who are also ACI members will be eligible to receive applications for the

ACI Foundation Student Fellowship Program. After a student is formally nominated, the ACI Foundation will convey an official application directly to the nominated student.

Applications for ACI Foundation Graduate and Under-graduate Scholarships are available on the ACI Student Scholarship Web page to the general student population and do not require a faculty nomination.

Deadline for applications is October 12, 2012. For more information, visit www.scholarships.concrete.org.


SDC’s New Chair and Board Members

Earlier this year, the concrete industry’s Strategic Develop-ment Council (SDC), a

council of the ACI Foundation, announced its new Chair and Board members. The new Chair of SDC is Mike Schneider, Senior Vice President and Chief People Officer at Baker Concrete Construction, Inc. He has been with Baker Concrete Construction in Monroe, OH, for over 33 years. He started at Baker as a Project Manager in 1978 and helped open Baker’s Houston, TX, office in 1982. During his career, he has been involved in a multitude of projects, ranging from high-rise offices to automotive plants to mainline concrete paving.

He has been active in the American Society of Concrete Contractors (ASCC) for the past 15 years and served as President during 2005 and 2006. During 2001 and 2002, he was a member of the Board of Directors for the National Center of Construction Education and Research. In addition, he is Co-Chair of the Joint ACI/ASCC Task Force, Chairman of the National Steering Committee for the Construction Industry Management Program. He has served as Co-Chair of the Contractor Task Group for the National Ready Mixed Concrete Association’s P2P Task Force, and as a Board Member and Past Chair for the Concrete Promotion Council of Southwest Ohio. In 2005, Concrete Construction magazine named him as one of the 10 most influential people in the concrete industry.

Schneider was named an ACI Fellow in 2006, received the ACI Roger H. Corbetta Concrete Constructor Award in 2011, and served on the ACI Board of Direction from 2008 to 2010. He currently chairs the Construction Liaison Committee and is a member of ACI Committees 117, Tolerances; 132, Responsibility in Concrete Construction; Chapter Activities Committee; Convention Committee; Financial Advisory Committee; and Student Activities Committee. He received his bachelor’s degree in personnel

management from Miami University (Ohio) and his bachelor’s degree in construction management from the University of Cincinnati.

The four new Board members, who have begun 3-year terms, include Kevin Cail, Brian Green, Charles Hanskat, and Claudio Manissero.

Kevin Cail is Director of Sustain-ability and Innovation for Lafarge North America and is responsible for Lafarge North America’s sustainability efforts; he is based in the Washington, DC, area. As Director, his main role is to work on key corporate sustainability initiatives throughout the four business units of Lafarge North America, Cement Division. In addition, he is also responsible for the commercial development of various innovation projects and product changes. He also manages and develops policy and direction related to those activities.

Cail serves on the Board of Directors for the Canada Green Building Council, working on issues related to industry and sustainability. He is active in the Code work of various Canadian Standards Association (CSA) technical committees related to cement and supplementary materials in Canada. He was recently elected to the Executive Committee of the CSA Cement and Supplementary Cementitious Materials Committee. He also participates in a number of trade organizations in both the U.S. and Canada and represents Lafarge as the Co-Chair of the Sustainability Committee for the Portland Cement Association.

A graduate of the University of New Brunswick in civil engineering, Cail has worked with Lafarge since 1980. During this time, he has held various positions in manufacturing operations, sales, research, marketing and, most recently, sustainability and innovation. During his career with Lafarge, he has had the opportunity to travel extensively in North America and Europe, working and speaking on issues related to cement, concrete, and supplementary cementitious materials. He has co-authored a number of papers on concrete performance and innovation.

Schneider

Cail


Brian Green, FACI, is a Research Geologist specializing in grout and concrete materials research in the Concrete and Materials Branch, Geotechnical and Structures Laboratory, U.S. Army Engineer Research and Development Center (ERDC), located in Vicksburg, MS.

Green serves as Chair of the SDC Cracking Accelerated Implementation Team. He is Secretary of ACI Committee 552, Cementitious Grouting; and a member of ACI Committees 229, Controlled Low-Strength Materials; 239, Ultra-High Performance Concrete; and ACI Subcommittee 236-D, Material Science—Nanotechnology of Concrete. He also serves on the Board of Directors for the ACI Mid-South Chapter.

His research interests include the development of structural grouts, high-strength concrete, fiber-reinforced concrete, controlled low-strength materials, roller-compacted concrete, mass concrete, and ultra-high performance concrete. He coordinates and teaches in the Corps of Engineers’ PROSPECT Courses on “Concrete Fundamentals” and “Concrete Maintenance and Repair” that provide the Corps of Engineers, Army, Navy, Air Force, and other federal agencies a week-long intensive course of study.

Green has extensive field and laboratory work experience providing past research and development support and collaboration to the Department of Energy, Sandia National Laboratory, and Lawrence Livermore National Laboratory. He has also supported the Defense Nuclear Agency, Defense Special Weapons Agency, Defense Threat Reduction Agency, and Department of Homeland Security.

He is a member of Sigma Xi International and a licensed professional geologist in Mississippi.

Charles Hanskat, FACI, is Owner of Hanskat Consulting, a firm located in Northbrook, IL. He is a licensed professional engineer in 22 states. He has been involved in the design, construction, and evaluation of environmental concrete and shotcrete structures for nearly 35 years.

Hanskat is the Chair of ACI Committee 376, Concrete Structures for Refrigerated Liquefied Gas Containment, and is a founding and current member of ACI Committees 371, Elevated Tanks with Concrete Pedestals, and 372, Tanks Wrapped with Wire or Strand. He also serves on several other ACI technical and standing Board committees, including 301, Specifications for Concrete; Construction Liaison Committee; Marketing Committee; and TAC Design Standards Committee. He is a Board member of the American Shotcrete Association (ASA) and Chair of the ASA Sustainability Committee.

Hanskat has been active in professional and technical engineering societies since he was in engineering school.

His service to the American Society of Civil Engineers (ASCE), the National Society of Professional Engineers (NSPE), and the Florida Engineering Society (FES) in over 50 committee and officer positions at the national, state, and local levels was highlighted when he served as State President of FES and then as a National Director of NSPE. He served as a District Director for Tau Beta Pi for 25 years from 1977 to 2002.

He received national recognition from ACI with the Delmar L. Bloem Distinguished Service Award in 2001. For his dedication and service to the engineering profession while in Florida, he was named the Young Engineer of the Year by FES and Engineer of the Year by the Florida Section of ASCE and received the Tau Beta Pi Distinguished Service Award. He received his bachelor’s and master’s degrees in civil engineering from the University of Florida.

Claudio E. Manissero is President of Premier Construction Products Group, Huntersville, NC. The company specializes in technologies to decrease cracking of concrete and increase its durability and is also developing new technologies for magnesia-based board and decorative panels. Previously, he was Sales and Marketing Manager for FMC Lithium Division in Charlotte, NC, where he managed construction additives and remediation projects, including lithium-based products for mitigation of alkali-silica reactivity (ASR).

He has participated as an Expert Task Group (ETG) member on Strategic Highway Research Project (SHRP) programs on ASR and electrochemical chloride extraction, was a member of the American Association of State and Highway Officials SHRP Implementation ASR Lead State Team, and has been a speaker at several of the SHRP ASR Showcases. He served on the National Cooperative Highway Research Program ASR Long-Term Pavement Performance ETG and the American Concrete Pavement Association/Portland Cement Association Concrete Durability Task Force.

Manissero participated in the development of Vision 2020 for the concrete industry. He is a past Board member of the National Safe Skies Alliance, which conducted ASR research projects for the Federal Aviation Administration. He was also involved with the U.S. Army Corps of Engineers through a cooperative research and development agreement on ASR projects involving military airfields and worked with the U.S. Military Tri-Services Group on new ASR specs. He was a member of the Federal Highway Administration Lithium Implementation program, the Engineering Technical Committee for the Airport Consultants Council, and the National Institute of Standards and Technology team on nuclear specs.

For more information about SDC, visit www. concreteSDC.org.

Green

hanskat

Manissero


Concrete Reinforcing Steel Institute Announces 2012 Design Award Winners

The Concrete Reinforcing Steel Institute (CRSI) has announced the winners of the 2012 CRSI

Design Awards program. For almost 40 years, the CRSI Design Awards program has honored excellence in reinforced concrete structures and acknowledged their designers. The CRSI Design Awards program is open to architects, engineers, contractors, and fabricators; and eligible structures must be located in the United States, Canada, or Mexico. Entries are evaluated on aesthetics, innovation, engineering achievement, functional excellence, and economy of construction.

This year’s winners are:

Multi-Family Residential Winner

Escala, Seattle, WA The 31-story cast-in-place structure,

located in downtown Seattle, was designed without a central core; it relies on dispersed shear walls and ductile moment-resisting frames for lateral force resistance. To meet requirements for seismic confinement reinforcing, ASTM A1035 Grade 100 reinforcing steel was used, which reduced steel tonnage and labor and made Escala the first building in North America to use Grade 100 steel. A high-strength, low-shrinkage concrete mixture was used to allow an entire floor to be cast in one placement and allow post- Escala, Seattle, WA

tensioning in 2 days. A column-hung slab forming system eliminated the need for shores and reshoring.

Project Credits: Harris Rebar, Reinforcing Bar Fabricator; Mulvanny G2 Architecture, Architect; Cary Kopczynski & Company, Engineer; JE Dunn Construction Company, Contractor; Lexas Companies, Owner.

Submitted by Cary Kopczynski & Company, Bellevue, WA.

Commercial Winner

The James, New York, NYThe James is an 18-story hotel in

Manhattan whose design features are both structural and architectural. Four large columns and the building core support the building from the base up to the third floor, where transfer girders support the guest suite columns and suspend the lobby below. The suite floors are framed with an 8 in. (200 mm) thick controlled modulus lightweight concrete slab supported on 9 in. (230 mm) wide columns. The James also features a rooftop pool suspended from the roof slab.

Project Credits: Perkins Eastman Architects, Architect; DeSimone Consulting Engineers, Engineer; Brack Capital Real Estate, Contractor and Owner.

Submitted by DeSimone Consulting Engineers, New York, NY.

Honorable MentionCity View, Los Angeles, CA Project Credits: Central Reinforc-

ing Corp., Reinforcing Bar Fabricator; Abramson Teiger Architects, Architect; Weidlinger Associates, Inc., Engineer; Del Amo Construction, Contractor; Third Street City View, LLC, Owner.

Submitted by Abramson Teiger Architects, Culver City, CA.


Educational Facility Winners

Mascaro Center for Sustainable Innovation, Pittsburgh, PA

This three-story addition to Benedum Hall at the University of Pittsburgh Main Campus was built on top of and through the existing two-story basement. The structural system consisted of two-way site-cast concrete flat slabs supported by concrete columns and walls. Micropile foundations were installed in the basement of the existing building and the concrete columns rose from pile caps through two existing concrete-framed floors to support the floors and roof. Architectural features include tapered, site-cast “Y” and “K” columns that support stairs and landings.

Project Credits: Whitacre Engineering Company, Reinforcing Bar Fabricator; Edge Studio, Architect; Atlantic Engineering Services of Pittsburgh, Engineer; Mascaro Construction Company, Contractor; University of Pittsburgh, Owner.

Submitted by Atlantic Engineering Services of Pittsburgh, Pittsburgh, PA.

St. Joseph Seminary, Edmonton, AB, Canada The St. Joseph Seminary was designed on the basis that

the Catholic Church thinks in terms of hundreds of years; traditional church architectural features were reinterpreted with modern materials and incorporated into an overall modern design that is intended to last. The walls were made from white, self-consolidating concrete cast in a single placement and the interior walls were left exposed. All reinforcing was chaired and tied to the outside of the wall so nothing would show on the inside. This was achieved by erecting the inside face of the formwork first, allowing the wall reinforcement to be tied in place before completing the outside form.

Project Credits: A & H Steel Ltd., Reinforcing Bar Fabricator; DIALOG, Architect and Engineer; Dawson Wallace Construction Ltd., Contractor; Catholic Archdiocese of Edmonton, Owner.

Submitted by DIALOG, Edmonton, AB, Canada.

Honorable Mention Golden West College Learning Resource Center,

Huntington Beach, CAProject Credits: Harris Rebar, Reinforcing Bar Fabricator;

Steinberg Architects, Architect; IDS Group, Inc., Engineer; URS Corporation, Contractor; Coast Community College District, Owner.

Submitted by IDS Group, Inc., Irvine, CA.

For a complete description of the CRSI Design Award program and contest rules, visit the CRSI Design Awards Web site at www.crsi.org/index.cfm/news/ 2012_winners.

The James, New york, Ny

Mascaro Center for Sustainable Innovation, Pittsburgh, PA

St. Joseph Seminary, Edmonton, AB, Canada


Stamped and stained walkway for the front garden at SAy Sí



Creating Decorative Floors…and a Dinosaur, TooArtistry and altruism displayed at the Concrete Decor Show

The trainers and workshop attendees who participated in this year’s Concrete Decor Show benefited the community in San Antonio, TX, leaving behind some

varied examples of the artistry that can be achieved when concrete is the medium. Held February 20-24, 2012, the third annual Concrete Decor Show included hands-on workshops, technical seminars, and technique demonstrations.

Makeover for Youth Arts Center SAY Sí is a year-round, nonprofit multidisciplinary arts

program established in 1994 to bring arts education to San Antonio high school and middle school students. The program moved into its present SAY Sí Central location within San Antonio’s arts district in 2007. The Concrete Decor Show’s hands-on courses took place at several locations throughout the building. More than 5500 ft2 (510 m2) of flooring surfaces received decorative treatments.

Floor applicationsArt Gallery—Course: Mastering Polyaspartic Coatings;

Lead Trainers: Trevor Foster, Miracote, and Bill Young, Concept Art and Design.

The space where the emerging artists at SAY Sí sell their artwork needed an aesthetic treatment, but it was necessary to keep the floor design subtle to avoid detracting from the work on the walls. Foster and Young oversaw the renovation using polyaspartics in earth-tone colors in a simple design of circles and soft lines.

The Black Box Theatre—Course: Creating Decorative Effects with Metallics; Lead Trainer: Troy Lemon, Cornerstone Decorative Concrete.

For the performance space of the facility, Lemon applied various metallic epoxies and polyaspartics donated by Ardex, the Stain Store, and Westcoat on 75% of the floor.

Working Artisans and Mentors (WAM) Room—Course: Restoration with Polishable Overlays; Lead Trainer: George Lacker, GLC3 Concrete. A stamped and painted overlay was added to the entrance of SAy Sí


The vestibule area received a colored epoxy treatment

The Art Gallery floor was renovated using polyaspartics in earth-tone colors A polished, stenciled, and stained floor in the Visual Arts Studio


Directly off the foyer is SAY Sí’s WAM Room, where middle school students are mentored by high school students and taught visual and media arts. Lacker conducted a workshop on applying and polishing a 1/2 in. (13 mm) overlay.

Vestibule—Project Leaders: Rachel Bruce, FLOORmap Stencil Designs, and Ryan Samford, Epo-Floors LLC.

The bands of color in SAY Sí’s Visual Arts Studio aren’t the only place they are located in the building. In fact, they appear to flow into colored bands that Bruce and Samford created as a side project in the facility’s vestibule area—on the other side of a doorway from the studio. The bands and main floor surface in the foyer were an epoxy rather than a polish and stain job.

Visual Arts Studio—Course: Fundamentals of Polishing; Lead Trainer: Adrian Henry, Diacon Decorative Polished Concrete.

The floor of the 1400 ft2 (130 m2) Visual Arts Studio started off in rough shape. After an initial grind and treating some particularly poor areas of the floor, however, trainers and students brought it up to a 400-grit finish. Next, Rachel Knigge-Bruce of Floormap Stencil Designs helped apply a stencil to create four bands of dyed color from Prosoco, and the floor was brought up to a 3000-grit finish. Henry also noted that the floor was treated with a sealer that is UV-stable because it’s exposed to a large amount of natural light.

Other decorative treatmentsFront Garden—Course: High-End Stamped Concrete

and Custom Features; Lead Trainer: Jason Geiser, Deco-Crete Supply.

Greeting guests to SAY Sí is an elaborate front garden with hardscaping largely crafted by the students in this workshop. Attendees joined a crew from Deco-Crete Supply to stamp more than 600 ft2 (55 m2) of concrete, add colored borders and bands with color hardener, and stain individual stones within the stamped pattern. To improve the surface’s high-end look, grout was applied between the stones before sealing. The key highlight of the installation is the SAY Sí logo created with glow-in-the-dark aggregates from Ambient Glow Technology and surrounded by about 100 fiber optic lights from Fiber Creations.

Front Garden—Course: GFRC Water-Feature Design and Build Workshop: Featuring Advanced Colorization Techniques; Lead Trainer: David Montoya, StoneMakers Corp.

Adjacent to the logo and lighting feature is a large waterfall constructed using placed concrete for the pool area and lower rocks and GFRC panels to create the upper-level rocks.

Front Entrance—Special pre-show project completed in January 2012; Project Leaders: Trevor Foster, Miracote, and Keith Boudart, Butterfield Color.

San Antonio’s famed Riverwalk inspired the design. A stamped overlay was applied over most of the surface area with varying earth-tone colors and textures and a troweled

microtopping representing the San Antonio River. The “river” flows from the building to the water feature in the Front Garden.

To complete the nearly 2000 ft2 (185 m2) of surface area in just 1 week, workers from Butterfield and Miracote teamed up with local contractors to take on the massive overhaul. After losing a day due to unexpected additional surface prep, the crew had to put in 12- to 15-hour days to meet their deadline. Once the overlay was dry, SAY Sí students painted flora and fauna native to Texas and added quotes that reflect their experiences with the youth arts organization.

Back Garden Area—Course: Introduction to Vertical Carving and Sculpting; Lead Trainer: Nathan Giffin, Vertical Artisans.

For a planned garden area, the focal point is a faux wooden door textured to resemble wood from a tree native to southern Texas. Sculpted rocks border both sides of the door and a wood-like header completes the frame around the door.

A Dinosaur Sculpture Takes ShapeWitte Museum Dinosaur—Course: Dinosaurs Go

Decorative: Theming in Large Scale; Lead Trainer: Thom Hunt, Big Bamboo Studios (R.A.T. International).

A life-sized replica of a dinosaur that inhabited the region around Texas 200 million years ago now greets visitors at the Witte Museum—another gift for the children of San Antonio left behind by the Concrete Decor Show. Artisans Thom Hunt and Mark Whitten led an herculean effort to construct, sculpt, and color the replica of Acrocan-thosaurus, a biped predator, which spans 30 ft (9 m) from nose to tail and is 13.5 ft (4 m) tall. The average time needed for a build for this size would be about a month, according to Mark Whitten; they completed the work in less than 3 weeks.

The front garden waterfall feature


The basic skeletal structure and scratch coat were done in advance of the Concrete Decor Show. About 120 hours were needed to construct the framework, which weighed almost 6000 lb (2700 kg). All the detailed sculpture work and coloring was undertaken at the Henry B. Gonzalez Convention Center and show attendees were able to watch the progress. Students at the workshop “Dinosaurs Go Decorative: Theming in Large Scale” participated in its creation, as did a few key volunteers.

When finished, the over 8000 lb (3630 kg) concrete dinosaur was craned onto a truck and transported across the city to its new location.

Professional Trade Publications, Inc., publishers of Concrete Decor magazine, will hold the fourth annual Concrete Decor Show and Spring Training in Charlotte, NC, March 11-15, 2013. Visit www.concretedecorshow.com for more information.

Excerpts reprinted with the permission of Professional Trade Publications, Inc.Modeling and detailing a replica Acrocanthosaurus

The finished dinosaur (photo courtesy of Professional Trade Publications, Inc.)

August 2012—Mixing, Placing & Curing September 2012—Software, Technology & Design

October 2012—Precast/Prestressed & Post Tensioned

Upcoming Themes

For advertising details, contact Jeff Rhodes • Phone (410) 584-8487 • e-mail: [email protected]


understanding Windbreak PrinciplesRequired height and length for typical placements may surprise you

by Bruce A. Suprenant and Ward R. Malisch

Documents published by ACI and other industry organizations recommend erecting temporary windbreaks (Fig. 1) to reduce the evaporation rate in

fresh concrete and thereby minimize the occurrence of plastic shrinkage cracking.1-5 None of the documents, however, describe the windbreak height, porosity, length, orientation, or continuity needed to reduce wind speed to a benign level. Without such information, it’s difficult to determine if windbreaks comprise an economical and effective strategy for reducing the evaporation rate.

Benefits of Reducing Wind SpeedSurface drying of fresh concrete is initiated whenever the

evaporation rate is greater than the bleeding rate: the rate at which water rises to the surface of recently placed concrete. High concrete temperatures, high wind speed, low air temperatures, low relative humidity, or a combination of these can cause rapid evaporation of surface water.

ACI 305R-104 indicates that the probability of plastic shrinkage cracking increases whenever the environmental conditions increase evaporation or when the concrete has a low bleeding rate. It also indicates that experience in limiting plastic shrinkage cracking has led to specified allowable evaporation rates from 0.05 to 0.2 lb/ft2/h (0.25 to 1.0 kg/m2/h).

Evaporation rates can be estimated using a nomograph published in References 1 and 4, with the wind speed, one of the most important variables, measured at an elevation about 20 in. (0.5 m) above the top of the concrete slab. For example, with a relative humidity of 50%, an air temperature of 80°F (27°C), and a concrete temperature of 80°F (27°C), reducing the wind speed from 15 mph (24 km/h) down to 5 mph (8 km/h) reduces the evaporation rate from 0.2 to 0.1 lb/ft2/h (1.0 to 0.5 kg/m2/h).

The effect of a windbreak on a concrete placement is shown schematically in Fig. 2, with bleeding and evaporation plotted as functions of time after placement. A critical point

Fig. 1: Windbreaks may be needed in cold weather because low air temperature, low relative humidity, and high wind speeds can lead to plastic shrinkage cracking (Photo courtesy of Portland Cement Association)

Time since placing

Cumu

lative

bleed

ing or

Cu

mulati

ve eva

porat

ion

Time ofsetting

Cumulativeevaporation

(without windbreak)CriticalpointCumulative

bleeding

Cumulativeevaporation

(with windbreak)

Fig. 2: Schematic representation of the effect of a windbreak on evaporation rate and potential for plastic shrinkage cracking. A windbreak results in a significant reduction in the evaporation rate. The evaporation may remain below bleeding from placement until the time of setting (modified from Reference 5)


occurs when evaporation exceeds bleeding before the time of setting. In many place-ments, critical points occur very soon after placement, when bleed water has not yet reached the surface, and shortly before the time of setting, when the bleeding rate of the mixture slows. The concrete may endure the first critical zone because the mixture is plastic enough to simply shrink into a thinner placement and finishing operations will close incipient cracks, but the second critical zone could cause damage. The example shows that a significant reduction in evaporation rate (in

this case, obtained with a windbreak) has the potential of eliminating both critical zones.

Windbreak FunctionFor over a century, the effects of windbreaks (shelterbelts

and fences) have been studied for their effects on local and microclimates. These studies show that the height, porosity, length, orientation, and continuity of a windbreak are key factors that affect the wind speed in the sheltered zone downwind of the windbreak.

HeightWindbreak height H is the most important factor

determining the area protected downwind. The flow pattern resulting from a windbreak is illustrated schematically in Fig. 3. The region of disturbed flow downwind of the windbreak is divided into two zones: the wind shadow and the remainder of the wake. The former, an area with an eddying flow, is generally about 10 to 15H downwind. Incident flow is reestablished about 40H downwind. Measurements show that the near-surface wind speeds behind a solid windbreak will be at or below 50% of the open-field wind speed only within a distance of 7H down-wind (Fig. (4a)). Therefore, an 8 ft (2.4 m) tall solid windbreak will reduce a 20 mph (32 km/h) wind to about 10 mph (16 km/h) within a shielded area limited to only about 55 ft (16 m) from the barrier.

Porosity If the windbreak is porous, air bleeding through it will

increase the pressure immediately adjacent to the down-wind face. Increasing the porosity moves the position of the minimum wind speed leeward and the width of the protected area will increase. As can be seen in Fig. 4(c), the greatest protection is provided by the barrier with 40% porosity. Wind speeds behind a windbreak with 40% porosity will be at or below 50% of the open-field wind speeds within a distance of about 10H downwind (Fig. 4(c)), so an 8 ft (2.4 m) porous barrier will reduce a 20 mph (32 km/h) wind to about 10 mph (16 km/h) within a shielded area of about 80 ft (24 m) from the barrier. Windbreak heights required for downwind surface

Undisturbed flow Undisturbed

flow

Eddying flow

Eddy

Turbulent flowsurface of

separation3H

H

2H

50 to100H10 to 15H 2 to 5H

Fig. 3: A schematic of the effect of a windbreak. Although the wind flows over the barrier, the pressure drop in the wind shadow results in eddying flow that can have significant speeds (based on Reference 6)

1.00.90.8

0.70.6

0.50.4

00 4 8 12 16 20

2

1 0.3

1.00.9

0.80.7

0.60.5

0.40.30.2

1.00.90.8

0.7

1.00.9

0.80.7

0.6

0.6

0.5

0.5

0.4

0.4

0.3

Leeward distance in barrier heights H

Vertic

al dis

tance

inba

rrier

heigh

ts H


Vertic

al dis

tance

inba

rrier

heigh

ts H


Vertic

al dis

tance

inba

rrier

heigh

ts H


Vertic

al dis

tance

inba

rrier

heigh

ts H

00 4 8 12 16 20

2

1

00 4 8 12 16 20

2

1

00 4 8 12 16 20

2

1

(a)

(b)

(c)

(d)

Fig. 4: Ratio of leeward to windward wind speed downwind of a windbreak: (a) solid windbreak; (b) 20% porosity; (c) 40% porosity; and (d) 60% porosity. As the porosity increases, the position of the minimum wind speed moves downwind. The 40% porous windbreak produces the lowest wind speed over the largest area (based on Reference 7)

(a)

(b)

(c)

(d)


wind speeds of 40 to 60% of open-field wind speeds are summarized in Table 1.

Orientation, length, and gapsTo be most effective, a windbreak must be perpendicular

to the wind direction. Also, the length of a windbreak must exceed the length of the intended protected area—not only because wind directions shift, but eddies at the ends of windbreaks can increase local wind speeds and reduce the protected area. Figure 5 shows the protected areas created by one- and two-legged windbreaks with winds blowing in different directions. Obviously, a shift in wind direction could render a one-legged windbreak useless. Although a two-legged windbreak will help avoid this problem, the protected area is still limited. Creating a full-perimeter windbreak will provide the most reliable (and expensive) protection. Gaps will cause locally high wind speeds, so openings required for access should be located on the downwind face only.

Applications for Concrete PlacementsThe application of windbreaks varies depending on the

concrete placement type: • Slab-on-ground; • Elevated slab; and • Topping slab.

Slab-on-groundConcrete slab-on-ground placements are usually strip or

block placements that range in size from about 10,000 to 30,000 ft2 (900 to 2800 m2). Strip placements are usually in width increments of column spacing (bays) and lengths of five to 10 bays. Thus, for a typical 30 ft (9 m) column spacing, concrete strips would be 30 ft (9 m) wide and up to 300 ft (90 m) long. Contractors might place one, two, or three strips in one concrete placement, resulting in total placement areas of 9000, 18,000, or 27,000 ft2 (850, 1700, or 2500 m2).

Based on Fig. 4 and Table 1, to reduce the wind speed by 50% everywhere on a concrete placement of width W, the solid windbreak height H would need to be W/7. So, for a 30 ft (9 m) wide strip placement, H would need to be about 4 ft (1.2 m).

Assuming the wind will blow only across a strip place-ment, the length of a one-legged windbreak needed to protect the placement will be the placement length plus two placement widths (L + 2W). Table 2 shows the windbreak

Table 1:Windbreak heights required for specific wind reductions for windbreaks with various porosity (based on Fig. 4)

Windbreak type

Leeward wind speed, % of

open-field wind speed

Required windbreak height H as a

function of protected zone width W

Solid

40 W/4

50 W/7

60 W/13

20% porous

40 W/4.5

50 W/6

60 W/13

40% porous

40 W/8

50 W/10

60 W/12

60% porous

40 W/7

50 W/8.5

60 W/11

Table 2:Requirements for windbreak to reduce wind speed by 50% over entire strip placement width

Concrete placement: W x L, ft (m)Placement

area, ft2 (m2)Windbreak

height, ft (m)Windbreak length,

ft (m)Total Windbreak area,

ft2 (m2)

One strip: 30 x 300 (9 x 90) 9000 (850) 4 (1.2) 360 (110) 1440 (132)

Two strips: 60 x 300 (18 x 90) 18,000 (1700) 8 (2.4) 420 (130) 3360 (312)

Three strips: 90 x 300 (27 x 90) 27,000 (2500) 12 (3.6) 480 (150) 5760 (540)

Wind direction

Winddirection

Winddirection

Windbreak Windbreak

Windbreak

Protectedzone

Wind direction

Windbreak

Protectedzone

Protectedzone

(a)

(b)

Fig. 5: The protected zones for windbreaks with one or two legs (based on Reference 8): (a) a single leg provides protection only when the wind is perpendicular to the leg; and (b) two-legged windbreaks protect the same area when winds are normal to either leg (based on Reference 8)

(a)

(b)


height, length, and area required for placement widths of 30, 60, and 90 ft (9, 18, and 27 m). Values are rounded down to the nearest 1 ft.

A schematic of the 30 ft (9m) placement (Fig. 6) shows the relative scale of the windbreak. Whether temporary plywood fencing or polyethylene sheeting attached to dimension lumber frames are used, the cost will be significant, depending on the ability to move and reuse the windbreak.

Fig. 6: To reduce wind velocity by 50% over a 30 ft (9 m) wide protected zone, a 4 ft (1.2 m) high windbreak is needed. To protect a 30 x 300 ft (9 x 90 m) concrete strip placement, a one-legged windbreak must be 360 ft (110 m) long

Winddirection

Windbreak

Strip placement

30 ft

30 ft

30 ft

300 f

t

Winddirection

Protectedzone

Windbreak

Blockplacement

150 ft

150 f

t15

0 ft

Fig. 7: To reduce wind velocity by 50% for a 150 x 150 ft (46 x 46 m) block placement, a windbreak must be 20 ft (6 m) high. Two 300 ft (90 m) long legs will provide the needed protected area, but at a very high cost

Windbreaks for block placements are even less economical than windbreaks for strip placements. For example, consider a 150 x 150 ft (46 x 46 m) slab-on-ground concrete placement protected with a two-legged windbreak (Fig. 7). In order to achieve a 50% reduction in wind speed, the windbreak would need to be over 20 ft (6 m) tall. The length of each leg of the windbreak would need to be 300 ft (90 m), so the total windbreak area would be at least 12,000 ft2 (540 m2). A 20 ft (6 m) tall windbreak would be particularly costly, given that the design wind speed for a temporary barrier could be as high as 75% of the basic wind speed required for the design of a permanent structure.9

Elevated slabWhile perimeter safety fencing is common for elevated

construction, its height is generally limited to 4 ft (1.2 m), so wind protection will be limited. The windbreak require-ments for elevated concrete placements on reinforced concrete frames are similar to those for slabs-on-ground, except the windbreaks need to be positioned above ground. Because of the increased costs for labor and equipment to transport materials and erect them, these windbreaks would be even less economical than those for a slab-on-ground.

Enclosed topping slabWindbreaks for topping slabs placed on metal deck or

precast members can be created by using wood and plastic sheathing around the building perimeter at each floor. This type of windbreak effectively eliminates the wind and is less expensive to construct than other standing windbreaks. Windbreaks for this type of concrete placement may be economical, particularly when they also serve to enclose cold weather concreting operations.

Windbreaks May Be Impractical Industry recommendations for windbreaks appear to

have originated in the early 1940s and 1950s, when concrete placements were relatively small and evaporation reducers were not available. Windbreaks may be practical for small placements, but their construction may not be feasible for large strip or block placements of slabs-on-ground or for some elevated slabs.

One alternative is to use ride-on finishing machines equipped with containers holding evaporation reducers—solutions of organic chemicals in water that form a film over the bleed-water layer and reduce the rate of bleed-water evaporation.5 As Section 5.10 of ACI 302.1R-0410 indicates, evaporation reducers “…can be sprayed on the plastic concrete one or more times during the finishing operation…” Another alternative is a spray-on concrete finishing aid that does not retard evaporation but acts similar to water-reducing agents that break up cement flocs. This product is worked into the surface, freeing water trapped within the cement flocs and reducing the likelihood of plastic shrinkage cracking.


Bruce A. Suprenant, FACI, is a Concrete Consultant based in Boulder, CO. He is a member of ACI Committees 117, Tolerances; 222, Corrosion of Metals in Concrete; 228, Nondestructive Testing of Concrete; 302, Construction of Concrete Floors; C640, Craftsmen Certification; and the Construction liaison Committee.

Ward R. Malisch, FACI, is Technical Director for the American Society of Concrete Contractors (ASCC). He has been an ACI member for more than 40 years, is a licensed professional engineer, and has answered contractor questions on all aspects of concrete construction via the ASCC hotline for more than 20 years.

References1. Kosmatka, S., and Wilson, M., Design and Control of Concrete

Mixtures, Portland Cement Association, Skokie, IL, 2011, 440 pp.2. ACI Committee 302, “Guide for Concrete Floor and Slab

Construction (ACI 302.1R-04),” American Concrete Institute, Farmington Hills, MI, 2004, p. 63.

3. “Plastic Shrinkage Cracking (CIP 5),” National Ready Mixed Concrete Association, Silver Springs, MD, 1998, p. 2.

4. ACI Committee 305, “Guide to Hot Weather Concreting (ACI 305R-10),” American Concrete Institute, Farmington Hills, MI, 2010, p. 4.

5. ACI Committee 308, “Guide to Curing Concrete (ACI 308R-01) (Reapproved 2008),” American Concrete Institute, Farmington Hills, MI, 2008, 30 pp.

6. Gloyne, R.W., “Some Effects of Shelterbelts upon Local and Micro Climate,” Forestry, V. 27, No. 2, 1954, pp. 85-95.

7. Hagen, L.J., and Skidmore, E.L., “Turbulent Velocity Fluctuations and Vertical Flow as Affected by Windbreak Porosity,” Transactions of the ASAE, V. 14, No. 4, 1971, pp. 634-637.

8. Brandle, J.R., and Finch, S., “How Windbreaks Work,” University of Nebraska Extension EC 91-1763-B.

9. “Design Loads on Structures during Construction (SEI/ASCE 37-02),” American Society of Civil Engineers, Reston, VA, 2002, 36 pp.

10. ACI Committee 302, “Guide for Concrete Floor and Slab

Construction (ACI 302.1R-04) (Reapproved 2008),” American Concrete Institute, Farmington Hills, MI, 2004, 76 pp.

Selected for reader interest by the editors.

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Optimum Slab-on-Ground Concretelowering the water content of a minimized paste volume reduces curling

by Daniel M. Vruno and Michael J. Ramerth

The Minnesota Concrete Council (MCC) is dedicated to advancing education, technical practice, scientific investigation, and research in the field of cast-in-place

construction by organizing the efforts of its diverse member-ship as a nonprofit public service. The MCC and Target Corporation recently teamed together to gain pertinent knowledge about optimizing concrete proportioning to minimize curling, maximize finishability, and improve sustainability. This article summarizes the research. The work consisted of a 23 factorial statistical design laboratory phase and a 656 yd3 (500 m3) field placement phase. This approach allows the reader to judge the performance of the developed mixtures through both the laboratory and field phases.

Laboratory Phase Independent variables

A total of 13 concrete mixtures were included in the laboratory phase. Each mixture contained a well-graded blend of five aggregates ranging from 1-1/2 in. (38 mm)

gravel to sand. The grading followed the “8-18 rule,”1 with 8 to 18% of the combined aggregate retained on each standard sieve below the top size sieve and above the No. 100 (149 μm) sieve (refer to Fig. 1 for details). Three independent variables—water-cementitious material ratio (w/cm), total cementitious material content, and cement replacement levels—were considered at two levels (Table 1 and Fig. 2 and 3). (Detailed information on the composition of the concrete mixtures is provided with the online version of this article.)

The 11 mixtures included in the factorial study contained supplementary cementitious materials (SCMs). Mixtures 5 and 12 were not part of the factorial study, but they provided baseline data for a 100% portland cement mixture.

Dependent variablesThe dependent variables (that is, responses) included the

performance criteria of setting times, shrinkage, and finishability. Setting times were determined per ASTM C403/

C403M, Standard Test Method for Time of Setting of Concrete Mixtures by Penetration Resistance. Shrinkage (length change) was measured per ASTM C157/C157M, Standard Test Method for Length Change of Hardened Hydraulic-Cement Mortar and Concrete. Finishability was subjectively evaluated by three concrete finishers who applied a float finish to a test slab measuring 24 x 24 x 4 in. (610 x 610 x 102 mm). Each finisher used magnesium and wood floats and rated finish-ability using the following scale: 1—very difficult, 2—difficult, 3—moderate, 4—easy, and 5—very easy.

ResultsThe laboratory results are summarized in

Table 2 and Fig. 4 and 5. Setting times for the factorial points are summarized in Fig. 4, with

1

2

0

468

10

1214161820

Reta

ined p

ortio

n, %

of to

tal

Nominal Sieve Sizes (mm unless noted otherwise)

2 in.

(50)

1 1/2

in.(37

.5) 1 in.

(25.0) 3/4 in

.(19

.0) 1/2 in

.(12

.5) 3/8 in

.(9.

5)No

. 4(4.

75)

No. 8

(2.36

)No

. 16

(1.18

)No

. 30

(600 μ

m)No

. 50

(300 μ

m)No

. 100

(150 μ

m)No

. 200

(75 μm

)

Fig. 1: Aggregate grading was achieved using a blend of five aggregates and followed the Shilstone “8 to 18 rule”


Table 1: Independent variables for the 13 concrete mixture designs studied in the laboratory phase

Mixture No. w/cm Total cementitious material content, lb/yd3 (kg/m3) Cement replacement, % and type

1 0.45 520 (308) 40 fly ash

2 0.45 480 (285) 20 fly ash + 20 slag cement

3 0.45 480 (285) 40 fly ash

4 0.475 520 (308) 40 fly ash

5 0.45 520 (308) —



8 0.50 520 (308) 40 fly ash


10 0.50 480 (285) 40 fly ash


12 0.50 480 (285) —

13 0.50 500 (297) 40 fly ash

red factorial points highlighting the fact that mixtures with 40% fly ash cement replacement had somewhat longer setting times than mixtures with 20% fly ash and 20% slag cement, with an exception of Mixture 9. Shrinkage (% length change) results are presented in Fig. 5, with red factorial points indicating mixtures with shrinkage exceeding 0.030%. The results listed in Table 2 indicate that within each w/cm group (0.45 and 0.50), the mixtures with 520 lb/yd3 (308 kg/m3) total cementitious material shrunk slightly more than the mixtures with 480 lb/yd3 (285 kg/m3) total cementitious material.

For the mixtures with w/cm of 0.45, finishability was rated as 2—difficult and 3—moderate for the mixtures with 480 lb/yd3 (285 kg/m3) and 520 lb/yd3 (308 kg/m3) total cementitious material, respectively (Table 2). For the mixtures with w/cm of 0.50, finishability ranged from 2—difficult to 3—moderate for the mixtures with 480 lb/yd3 (285 kg/m3) total cementitious material, and from 3—moderate to 4—easy for two mixtures with 520 lb/yd3

No. 11

No. 9

No. 6

(a) (b) (c)

No. 1No. 3

No. 8

No. 10

No. 11

No. 9

No. 6

No. 1No. 3

No. 10

No. 2

0.450.50

No. 11

No. 9

No. 6

No. 1No. 3

No. 8No. 10

No. 2

520 lb/yd3480 lb/yd3

40% fly ash

20% fly ash20% slag cement

No. 8

No. 2

No. 11

No. 9

No. 7

No. 6

No. 1

No. 3

No. 4No. 8

No. 13No. 10

No. 2

Fig. 2: Factorial points for the independent variables included: (a) w/cm values of 0.45 and 0.50; (b) cementitious material contents of 480 and 520 lb/yd3 (285 and 308 kg/m3); and (c) cement replacements of 40% fly ash and 20% fly ash plus 20% slag cement

Fig. 3: Factorial and center points investigated for the study. Mixtures 4, 7, and 13 were included in the study to check the significance of curvature. Note that Mixtures 5 and 12 had zero cement replacement (100% portland cement mixtures) and are, therefore, not shown


Table 2: Summary of results from laboratory phase

Independent variables Dependent variables

Mixture No. w/cm

Total cementitious material, lb/yd3

(kg/m3)

Cement replacement, %

and type

Setting times: initial and final,

hr:min

Shrinkage (length change),

%Finishability

rating

1 0.45 520 (308) 40 fly ash7:40

10:400.030 3

2 0.45 480 (285)20 fly ash +

20 slag cement

6:37

9:350.025 2

3 0.45 480 (285) 40 fly ash7:50

10:040.027 2

4 0.475 520 (308) 40 fly ash7:49

10:380.032 3

5 0.45 520 (308) None7:03

8:480.033 2

6 0.45 520 (308)20 fly ash +

20 slag cement

7:20

9:520.031 2

7 0.45 500 (297)20 fly ash +

20 slag cement

7:16

9:500.027 2

8 0.50 520 (308) 40 fly ash7:58

10:220.034 4

9 0.50 520 (308)20 fly ash +

20 slag cement

7:38

10:450.033 3

10 0.50 480 (285) 40 fly ash7:47

10:300.030 3

11 0.50 480 (285)20 fly ash +

20 slag cement

7:02

9:300.029 2

12 0.50 480 (285) None5:14

7:080.031 2

13 0.50 500 (297) 40 fly ash7:49

10:240.031 3

No. 11(7:02)(9:30)

No. 9(7:38)

(10:45)

No. 7(7:16)(9:50)

No. 6(7:20)(9:52)

No. 1(7:40)(10:40)

No. 3(7:50)

(10:04)

No. 4(7:49)

(10:38) No. 8(7:58)

(10:22)

No. 13(7:49)

(10:24)

No. 10(7:47)

(10:30)

No. 2(6:37)(9:35)

No. 11(0.029)

No. 9(0.033)

No. 7(0.027)

No. 6(0.031)

No. 1(0.030)

No. 3(0.027)

No. 4(0.032) No. 8

(0.034)

No. 13(0.031)

No. 10(0.030)

No. 2(0.025)

Fig. 4: Initial and final setting times for the laboratory mixtures. Red circles indicate mixtures with initial and final setting times exceeding 7.5 or 10 hours, respectively

Fig. 5: Shrinkage (% length change) for the laboratory mixtures. Red circles indicate shrinkage exceeding 0.030%


(308 kg/m3) total cementitious material. Finally, mixtures with 40% fly ash replacement were generally reported to be easier to finish than mixtures with combined 20% fly ash and 20% slag cement replacement.

Field PhaseIndependent variables

Based on our analysis of the laboratory results, we selected four of the 13 laboratory concrete mixtures (Mixtures 2, 6, 10, and 11) for evaluation in a field study involving a slab-on-ground placement for a Target store in Inver Grove Heights, MN. The four mixtures were placed on January 31, 2012 (Fig. 6). One mixture was used in each of four 105 x 100 ft (32 x 30.5 m) sections in a 420 x 100 ft (128 x 30.5 m) strip in the middle of the store. The concrete quantity required for each section was 164 yd3 (125 m3).

Dependent variablesThe three dependent variables (setting time, shrinkage,

and finishability) examined in the laboratory study were also evaluated during the field study, using the same procedures as in the laboratory phase. The results of these tests are listed in Table 3.

Fig 6: Placement of the slab-on-ground floor for the Target store in Inver Grove heights, MN, on January 31, 2012

Table 3: Summary of results from field phase

Mixture No.

Independent variables Dependent variables

w/cmTotal cementitious

material, lb/yd3 (kg/m3)

Cement replacement, % and type

Setting times: initial and

final, hr:min

Shrinkage (length change),

%Finishability

rating

2 0.45 480 (285)20 fly ash +

20 slag cement

7:55

10:450.027 1

6 0.45 520 (308)20 fly ash +

20 slag cement

7:22

10:320.030 3

10 0.50 480 (285) 40 fly ash7:08

9:580.028 3

11 0.50 480 (285)20 fly ash +

20 slag cement

5:36

8:250.029 3

Table 4: Summary of FF and Fl numbers and curling for the four mixtures

Average F-numbers

Curling (50 days), in.

Initial, 1 day Final, 50 days

FF FL FF FL

Mixture 2 62.4 57.9 51.7 52.0 5/16

Mixture 11 61.6 39.4 40.8 34.5 5/16

Mixture 6 84.6 51.1 45.3 51.2 5/16

Mixture 10 68.8 41.2 42.9 38.4 5/16

1 in. = 25 mm

The results indicate that the mixtures with w/cm of 0.5 had somewhat shorter setting times than the mixtures with w/cm of 0.45. Length change (shrinkage) for all mixtures did not exceed 0.030%. Very difficult finishability was observed for Mixture 2 with w/cm of 0.45, 480 lb/yd3

(285 kg/m3) total cementitious material, and 20% fly ash and 20% slag cement replacement.


Flatness, levelness, and curlingACI 117-06, Section 4.8.5.1,2 provides floor surface

classification based on the specified overall values of flatness (SOFF) and levelness (SOFL). Flatness and levelness values are determined in accordance with ASTM E1155, Standard Test Method for Determining FF Floor Flatness and FL Floor Levelness Numbers. Higher flatness numbers (FF) indicate a flatter floor and higher levelness numbers (FL) indicate a more level floor. Both the flatness and levelness will typically decrease with time as the concrete shrinks and curls.

FF and FL evaluations were performed during the field phase using a Face Construction Technologies Dipstick Profiler at 1 day and 50 days after concrete placement. The measurement results are listed in Table 4. Based on the test results after 50 days and the difference between the 1-day and 50-day results, Mixture 2 provided the best average flatness and levelness.

The saw-cut joint spacing for the subject slab was typically 10 ft 7 in. x 10 ft 9 in. (3.2 x 3.3 m). Curling was measured at six saw-cut joints at each of the four test sections for a total of 24 readings. Measurements were made using a 10 ft (3 m) straightedge at 50 days after placement. The curling at each of the 24 measured locations was consistently 5/16 in. (8 mm), with no evident difference among the four mixtures.

Discussion of ResultsMixtures 5 and 12 (100% portland cement mixtures) set

faster than the other mixtures, experienced shrinkage (length change) greater than 0.03%, and had a low finish-ability rating of 2—difficult.

In the laboratory, we had control over many parameters that eluded our control in the field. As can be seen in Fig. 7, setting times varied significantly. The initial setting time for Mixture 2, for example, was considerably longer in the field than in the laboratory. In addition, although Mixture 2 had the shortest initial setting time in the laboratory phase, it had the longest initial setting time among the four mixtures placed in the field.

In addition, Mixtures 2 and 11, when tested in the lab, had the shortest final setting times in comparison with the other mixtures with SCMs. Nevertheless, during testing in the field, Mixture 2 had the longest final setting time, while Mixture 11 remained the fastest to set.

As was previously noted, the field placement occurred on a January day in Minnesota; the cold weather almost certainly was a major factor affecting the setting times. In winter placements, the ingredients that typically are heated at concrete plants are the sand and water. For each 10 yd3 (7.7 m3) load of concrete, mixtures with a w/cm of 0.45 will have 240 lb/yd3 (142 kg/m3) less heated water than mixtures with a w/cm of 0.50. Also, a portion of the volume of that amount of water is replaced with an equivalent volume of unheated (cold) aggregate. Finally, it’s important to note that Mixture 2 was used in the placement located closest to the truck entrance. That portion of the slab therefore experienced the coolest curing temperatures.

As can be seen in Fig. 8, Mixture 2 had the lowest shrinkage out of four mixtures evaluated in the laboratory and in the field. When tested in the lab, the finishability of Mixture 2 was comparable to Mixtures 6 and 11 and rated as 2—difficult (Table 2). While in the field, out of the four tested mixtures, the finishability of Mixture 2 worsened and had the lowest rating of 1—very difficult (Table 3).

ConclusionsThe data presented in Table 2 indicate the following

relative effects for the evaluated mixtures: • A lower w/cm combined with a lower total cementitious

material content slightly lowers the shrinkage and reduces finishability;

• A lower w/cm combined with a higher total cementitious material content results in greater shrinkage, no improvement in setting times, and slight improvement in finishability;

• A higher w/cm combined with a lower total cementitious material content slightly lowers the shrinkage and improves setting times and finishability; and

Fig. 8: Comparison of shrinkage achieved in the laboratory and field phases of the study

0:001:122:243:364:486:007:128:249:36

10:4812:00

Mixture 10 Mixture 6 Mixture 11 Mixture 2

Settin

g tim

e, h:m

in

Lab InitialField InitialLab FinalField Final

Fig. 7: Comparison of setting times achieved in the laboratory and field phases of the study

0.000

0.005

0.010

0.015

0.020

0.025

0.030

0.035

Mixture 10 Mixture 6 Mixture 11 Mixture 2

Shrin

kage

, %

LabField


ACI member Daniel M. Vruno is a Principal Engineer with American Engineering Testing, Inc., where he supervises the concrete batching laboratory. He is a current member of the Board of Directors of the Minnesota Concrete Council. In addition to being a licensed professional engineer in Minnesota, he also performs exterior flatwork from April through October for Nick’s Concrete.

Michael J. Ramerth is President and a Principal of Meyer Borgman johnson Structural Design and Engineering. Throughout his 37-year career, he has provided structural engineering services for many prominent projects in the Twin Cities area. He is Past President and a current member of the Minnesota Concrete Council (MCC) and a past Board member of the ACI Minnesota Chapter. As Chair

of the MCC Research Committee, Ramerth leads studies on green concrete, focusing on best mixtures and conditions for maximum durability. He received his BS in civil engineering from the university of Minnesota.

• A higher w/cm combined with a higher total cemen titious material content results in greater shrinkage, longer set times, and slightly better finishability.Although the plain portland cement mixtures had faster

setting times, shrinkage was increased and finishability was reduced relative to mixtures with SCMs.

An optimum slab-on-ground mixture design should minimize curling and maximize finishability. Based on these criteria, we judged Mixture 11 to be the optimum mixture for a slab-on-ground concrete. This mixture had a w/cm of 0.5 and a total cementitious material content of 480 lb/yd3 (285 kg/m3), the fastest setting time, shrinkage below 0.03%, and finishability rating of 3—moderate.

References 1. Shilstone, J.M. Sr., “Concrete Mixture Optimization,” Concrete

International, V. 12, No. 6, June 1990, pp. 33-39.2. ACI Committee 117, “Specifications for Tolerances for Concrete

Construction and Materials and Commentary (ACI 117-06),” American Concrete Institute, Farmington Hills, MI, 70 pp.

Note: Additional information on the ASTM standards discussed in this article can be found at www.astm.org.


Web SessionsTo bring you the latest information about concrete, ACI records select presentations from ACI Conventions and makes them available online and on-demand through a program called ACI Web Sessions. Each week, about 1 hour of new presentations will be posted to the ACI Web site. Best of all, these presentations can be viewed free of charge!

Simply register and log in on the ACI Web site to view these presentations. You don’t have to be an ACI member to take advantage of this program. Some of the presentations will also become part of the ACI Online CEU program, giving you the ability to earn Continuing Education Credits over the Internet.

To view these presentations, go to the ACI Web site at www.concrete.org, click on Education in the top menu, and then select the Web Sessions button on the left side of the page.


Self-leveling Floor Topping Saves the DaysSystem helps shave months off the construction schedule for a medical center

by Brad Fulkerson

Products&PracticeSpotlight

S labs on metal decking and steel framing can pose particular challenges for the concrete

contractor. This is especially so when floor finishes include rubber sheet flooring, sheet vinyl, and vinyl composition tile (VCT)—flat floor tolerances (floor flatness FF = 35/floor levelness FL = 25)1 and floor moisture limits must be met.

Using a cement-based topping course system, Sellen Construction, Seattle, WA, recently overcame these challenges in the construction of the Swedish Hospital and Medical Office Building in Issaquah, WA (Fig. 1). Sellen, which was the general contrac-tor for the project, self-performed the concrete work on the structure’s concrete-steel composite floors.

Optimal DecisionBefore construction began, Sellen

and the project owner made the decision to use the Laticrete® Supercap® System as a topping on the elevated concrete slabs. Because the topping would provide a flat and level finish, the concrete crews were able to finish the concrete slabs with a bull float. With no troweling needed, crews didn’t have to wait around for the concrete to stiffen and rainouts weren’t a concern. And, because the topping course was applied after the concrete slab had hardened, the

Fig. 1: The Swedish hospital and Medical Office Building in Issaquah, WA, was construct-ed in two phases. The first phase, a 200,000 ft2 (18,580 m2) medical office building, was completed in July 2011, and the second phase, a 156,000 ft2 (14,490 m2) 80-bed hospital, was finished 4 months later2

Fig. 2: Schematic section of a composite girder with slab on metal decking, vapor retarder, and self-leveling topping course3

Self-leveling concrete

Slab reinforcement

Steel girder

Shear studMetal decking

Vapor retarderPrimer coat

topping eliminated deflection issues with the composite slab and steel framing systems—the topped slabs were very flat.

The Supercap system includes an integral vapor barrier and a self- leveling topping course (Fig. 2) and

was installed by concrete specialty contractor ABW Construction. By eliminating the need to wait for the concrete to dry and ensuring minimal risk of grinding or other rework, the topping system trimmed the project schedule significantly.



And, having a flat and dry working surface allowed Sellen to optimize other construction activities: • Headwall millwork was prefabricated offsite so millwork

could be installed in units rather than as separate materials cut and fit on site;

• Wall framing was also cut to fit offsite and installed with no field trimming required;

• Door frames were set without shimming; and • Electrical outlets and fixtures were set using a template.

The optimized activities shaved time off the project schedule and enhanced the quality of the final project.

ConstructionConcrete slab

For each elevated floor in the hospital, the concrete slab was placed with a concrete pump boom truck, consolidated with a vibrating screed, and bull-floated to achieve a uniform texture (Fig. 3). No additional finishing was required, as the desired flatness and levelness were to be achieved by the topping.

The specified compressive strength for the slab concrete was 3500 psi (24.1 MPa) at 28 days. Concrete mixture proportions and concrete field data are listed in Table 1 and 2, respectively.3 A high-range water-reducing admixture (HRWRA) and mid-range water-reducing admixtures (MRWRAs) were used to maximize placement efficiency.

Surface preparationSeven days after the concrete slab was placed, the surface

was shotblasted to provide an absorptive and clean substrate for the application of a bonded moisture vapor retarder layer. Handheld diamond grinders were used in limited access areas. The shotblasting and grinding produced a base concrete slab with a surface profile (CSP) equivalent of CSP 5 (per ICRI 310.2-19974).3

The initial preparation was followed by a survey to locate cracks and establish the topography of the concrete floor (Fig. 4). To avoid leakage of the topping concrete,

Table 1:Concrete mixture proportions for suspended slab3

Materials Quantity

Type I-II cement, lb/yd3 (kg/m3) 449 (266)

Slag cement, lb/yd3 (kg/m3) 83 (49)

Coarse aggregate, lb/yd3 (kg/m3) 1932 (1146)

Fine aggregate, lb/yd3 (kg/m3) 1423 (844)

HRWRA, fl oz/yd3 (ml/m3) 10.5 (406)

MRWRA, fl oz/yd3 (ml/m3) 21.0 (812)

Water, lb/yd3 (kg/m3) 226 (134)

Table 2:Concrete field data3

Field data

Water-cementitious material ratio 0.425

Slump, in. (mm) 7.5 (190)

Concrete temperature, °F (°C) 73 (23)

Ambient temperature, °F (°C) 59 (15)

Fig. 3: Concrete finishing was completed with a bull float Fig. 4: Topography of concrete slab, level 4 West-North3

cracks in the slab were sealed by gravity filling with an epoxy grout, as described in ACI 224.1R-07.5 A 100% solids epoxy resin was mixed with fine sand, poured into the cracks and onto the slab surface, and consolidated and finished by manual trowelling.3

The topographic data were used to establish required topping thickness values. Elevation standards were cut to the appropriate depths and applied to the concrete on a regular grid to ensure the placed thickness wouldn’t exceed 1 in. (25 mm).

Capping it off The Supercap system was installed on 500,000 ft2 (46,450 m2)

of the project’s elevated decks. Installation of a typical



Supercap placement of about 30,000 ft2 (2790 m2) took a total of 4 days: 2 days for shotblasting, followed by surveying to determine required topping depths; 1 day for installation of moisture vapor retarder and setting elevation standards on the slab; and 1 day for application of primer and placing the topping.3

For each area to be topped, the first step was installation of a vapor retarder to the slab surface. Vaportight Coat-SG3 (SG3), manufactured by Aquafin Inc., a two-component, moisture-tolerant, low-viscosity, and solvent-free epoxy-based product was spread on the concrete slab with a notched squeegee and then finished with a nonshed roller to ensure uniform coverage (Fig. 5). SG3 reduces water vapor transmission levels of up to 25 to 3 lb/1000 ft2/24 h (12 to 1.5 kg/100 m2/24 h), often required for the installation of most floor-covering systems, including VCT, sheet vinyl, carpets, wood, laminates, epoxy, terrazzo, and synthetic.

After the epoxy had cured for about 24 hours, the concrete slab was primed with a one-part acrylic primer slurry (using Supercap powder). The cement-based topping was placed within 12 hours of the primer application and was installed using a special pump truck (Fig. 6) capable of continuously delivering up to 15 tons (13.6 tonnes) of topping mortar per hour. The pump is capable of delivering the mortar vertically up to 50 stories (about 500 ft [150 m]).

In addition to the pump, the truck has a crane, individual silos for cement and sand, a water storage tank, and a computer-controlled mobile blending unit (MBU). The granular material silos can be refilled through rooftop weathertight hatches using bulk sacks. The sacks are lifted into position and lowered through the hatches using the truck’s knuckle-telescope crane. The water tank can be filled by a hose from a local water source.

The truck’s MBU ensures proper proportioning and adequate mixing. Ingredients are continuously measured and metered into the mixer. Dry materials are transported from the unit’s premixer into its continuous mixer, where the correct proportion of water is injected. Actual mixing duration from the time the ingredients are interblended to the time the underlayment is discharged usually takes less than 10 seconds.

For each placement, a lubricating mixture is first pumped from the truck to the point of placement and discharged into a movable drum. Then, the Supercap topping is discharged onto the floor (Fig. 7). Placements are fast. It took only 7 hours, for example, to place 25,000 ft2 (2320 m2) of topping on the hospital’s Level 4 slab and sky bridge, and that time included cleaning the hoses and readying the pump truck for departure. The following day, the floor was ready for layout crews to mark wall and utility locations and serve as a working surface for the fireproofing contractor’s crews. The contractor discovered early in the project that the smooth, flat finish provided by the topping

allowed for rapid cleanup of the fireproofing overspray without obscuring layout marks—an unanticipated time-saving feature of the topping.

TestingTwo independent accredited laboratories conducted a

series of tests on the Supercap topping installed at the Swedish Hospital. Testing included compressive strength according to ASTM C109/C109M, Standard Test Method for Compressive Strength of Hydraulic-Cement Mortars (Using 2-in. or [50-mm] Cube Specimens); flexural strength according to ASTM C348, Standard Test Method for

Fig. 5: Application of the vapor retarder to the concrete slab. The epoxy-based coating was spread using a notched squeegee and finished using a nonshed roller

Fig. 6: The Supercap truck includes material storage silos and tanks, an MBu, and a pump. Granular materials can be loaded into the silos using a crane mounted behind the cab

Fig. 7: Supercap installation



Brad Fulkerson is the Managing Director of laticrete Supercap. Before joining laticrete, he served as the CEO of Avalon Flooring in Florida for 12 years, dealing with construction projects from the perspective of a Division 9 flooring and tile contractor. He received his BS in engineering and his MBA from the university of Michigan.

after the concrete substrate is placed, and flooring materials may be installed as soon as 1 to 3 days after the topping placement. Supercap eliminates the need for traditional concrete finishing, corrects for deflections of metal decking and steel framing, is stable under high moisture conditions, will not contribute to growth of mold or mildew, and will protect floor adhesives from the alkalinity and moisture in the underlying slab.

While construction of the Swedish Hospital and Medical Office Building was scheduled to take 12 months, Sellen Construction was able to complete the project in only 8 months—and almost 10% under budget. The contractor estimates that Supercap accounted for 25% of the savings in time and money.

References1. ACI Committee 117, “Specification for Tolerances for Concrete

Construction and Materials (ACI 117-10) and Commentary,” American Concrete Institute, Farmington Hills, MI, 2010, 76 pp.

2. “DJC 2011 Building of the Year Swedish/Issaquah Medical Center,” Daily Journal of Commerce, Mar. 26, 2012 (www.djc.com/news/co/12039152.html).

3. Allen, W., “Self-Leveling Underlayment and Bonded Topping Two-Coarse Slab Construction,” Supercap, Port Washington, NY, Mar. 2011, 25 pp.

4. International Concrete Repair Institute, “Selecting and Specifying Concrete Surface Preparation for Sealers, Coatings, and Polymer Over-lays,” Technical Guideline No. 310.2-1997 (formerly 03732), 1997, 41 pp.

5. ACI Committee 224, “Causes, Evaluation, and Repair of Cracks in Concrete Structures (ACI 224.1R-07),” American Concrete Institute, Farmington Hills, MI, 2007, 16 pp.

6. ACI Committee 555, “Removal and Reuse of Hardened Concrete (ACI 555R-01),” American Concrete Institute, Farmington Hills, MI, 2001, 26 pp.

Note: Additional information on the ASTM, ICRI, and CSA standards discussed in this article can be found at www.astm.org, www.icri.org, and www.csa.ca, respectively.


—Laticrete Supercap, LLCwww.laticretesupercap.com

Flexural Strength of Hydraulic-Cement Mortars; length change according to ASTM C157/C157M, Standard Test Method for Length Change of Hardened Hydraulic-Cement Mortar and Concrete; bond strength according to ASTM C1583/C1583M, Standard Test Method for Tensile Strength of Concrete Surfaces and the Bond Strength or Tensile Strength of Concrete Repair and Overlay Materials by Direct Tension (Pull-off Method); flatness and levelness according to ASTM E1155, Standard Test Method for Determining FF Floor Flatness and FL Floor Levelness Numbers; and pH according to ASTM F710, Standard Practice for Preparing Concrete Floors to Receive Resilient Flooring.

Samples of Supercap were obtained during installation in the West Wing of Level 4. Sampling was performed by collecting the material during a discharge of Supercap onto the concrete slab. Test specimens were molded within the specified time limits and consolidated by hand tamping. Hardened specimens were demolded at the test laboratory 4 hours after casting. Specimens were then placed in curing chambers until testing.

The average 28-day compressive and flexural strengths were 4870 and 945 psi (34 and 6.5 MPa), respectively. Average length change at 28 days was −0.046%.3

Pulloff tests conducted at 22 and 24 days after placement indicated tensile bond strengths of 335 and 345 psi (2.3 and 2.4 MPa), respectively, with a majority of bond failures at the concrete-overlay interface. Average tensile bond strengths obtained at 31 days ranged from 175 to 270 psi (1.2 to 1.9 MPa), with a bond failure predominantly in the overlay.3 Although the pulloff tests did not provide consistent results, they verified that the overlay was well-bonded to the substrate. Section 4.7.3.of ACI 555R-016 states: “CAN/CSA A23.2 recommends 145 psi (1.0 MPa) for bonded toppings when tested to the procedures described in CAN/CSA A23.2-6B.” (CAN/CSA A23.2, Methods of Test for Concrete, and CAN/CSA A23.2-6B, Method of Test to Determine Adhesion by Tensile Load, are equivalent to ASTM C1583/C1583M.)

The minimum specified overall flatness/levelness values for the finished floors were FF = 35/FL = 25 (flat per Section 4.8.5.1. of ACI 117-101). At an age of 30 days, the overall surface flatness/levelness values were FF = 87/FL = 46.3 in comparison to the values for the concrete slab of FF = 16/FL = 13.3 The achieved overall surface flatness/levelness values for the finished floors would classify them as super flat FF = 60/FL = 40) per Section 4.8.5.1 of ACI 117.1

Tests at 30 days indicated pH values of 8.4 to 8.5 for the topping course—much lower than the pH of 12 determined for the concrete surface.3

A System that SavesThe Laticrete Supercap is a pumpable and self-leveling

system that can be used to finish interior concrete and level uneven floor surfaces. It can be placed as soon as 5 days


Precooling Mass Concrete with liquid NitrogenAutomated system leads to increased use of the technology

by John Gajda and Francisco Sumodjo


The practice of precooling mass concrete is probably not as old as you think. The first reported use was at the Norfolk Dam, AR, in the early 1940s, where ice was

used to replace a portion of the batch water.1 The ice reduced the initial temperature of the concrete by about 10°F (5.6°C) due to the energy absorbed as the ice melted. Since then, using ice to precool concrete has become common.

But precooling concrete using ice has limitations. Because batch water only makes up about 5 to 10% of the mass of concrete mixtures, replacing most of the batch water with ice generally can reduce the initial concrete temperature only by about 20°F (11°C). If chilled water is

used instead of ice, the reduction in the initial concrete temperature is typically only about 2 to 3°F (1 to 2°C).

About 30 years ago, liquid nitrogen (LN) was first used to precool concrete. LN is far colder and occupies a smaller volume than ice, making it more convenient to transport and store. Initially, LN was used to cool the concrete ingredients prior to mixing; LN was sprayed on coarse and fine aggregates, and LN vapor was injected into cement storage silos and bubbled through water to make ice slurry for use as batch water.

However, these practices led to problems with concrete batching operations and concrete quality, were inefficient and costly, and achieved only about a 20°F (11°C) reduction in the initial concrete temperature (similar to that of replacing most of the batch water with ice). LN was later injected into the mixing drum at the batch plant or in the concrete truck, but this process was initially used sporadically.

In recent years, however, LN has become increasingly popular. LN-precooled concrete was used on large projects such as the Texas State Hwy. 45 Turnpike Project2; the new San Francisco-Oakland Bay Bridge3 (Fig. 1); the new Benicia-Martinez Bridge4; and the new Hoover Dam Bridge.5

The increased use of LN is largely because of the intro-duction of the automated CryoCrete™ system, developed by Air Liquide Industrial U.S. LP (Fig. 2). This system allows for the safe and efficient precooling of concrete in the drum of a concrete truck or a batch plant. It was used on the aforementioned projects and is being used at many other projects, including dams, buildings, bridges, power plants, and spillways.

With the increasing popularity of LN precooling, concerns arose regarding its effect on the fresh and hardened

Fig. 1: Night construction of the new Oakland Bay Bridge, San Francisco, CA, using an lN cooling system



properties of concrete. Research conducted for the Texas Depart-ment of Transportation by the University of Texas at Austin showed that LN has a minimal impact on the properties and performance of the concrete.6,7 Concrete performance was tested in terms of slump, setting time, yield, compressive strength, splitting tensile strength, elastic modulus, drying shrinkage, rapid chloride permeability, and hardened and fresh air void systems.

The amount of precooling required—and the associated cost—typically determine whether LN is used for full or partial precooling. LN precooling is used when the concrete needs to be cooled more than 20°F (11°C), when ice is not available, or when ice is more expensive than LN. Precooling with LN has the following advantages: • Repeatability: A batch of concrete can be cooled multiple

times with LN, including when concrete warms too much due to delays prior to placement;

• Mobility: The process can be performed at the batch plant, at the construction site, and even during transport on barges.8 A small generator provides enough power for the CryoCrete™ system;

• Utility: LN can and has been used to cool concrete to as low as about 35°F (2°C);

• Consistency: LN accurately changes the temperature of the concrete without changing the composition or characteristics of the concrete. Admixture batching is not affected; and

• Efficiency: Only one trained operator is required.A typical on-site LN cooling system consists of a cryogenic

vessel, a pressure regulating system, an automated injection lance, a control panel, a trained operator, and an infrared thermometer.

Liquid Nitrogen (LN) The earth’s atmosphere consists of about 78%

nitrogen. LN is atmospheric nitrogen that has been cooled to a very low temperature, sufficient for it to condense (convert from a gas to a liquid). Under typical conditions, LN boils (converts from a liquid to a gas) at a temperature of −321°F (−196°C). During this conversion, its volume expands by approximately 700 times.

In certain weather conditions, LN precooling can generate a ground fog, so cooling equipment should be located where it does not obstruct visibility for other operations. Personnel working with LN must be properly trained and equipped with safety equipment,7 as improper handling can result in the displacement of oxygen in the air and direct contact with LN can instantaneously freeze unprotected skin.

A video showing the LN injection equipment and process can be viewed at www.youtube.com/watch?v=mG-8hZfxeYE. Although the video shows

Night cooling with lN at a batch plant and generation of ground fog

the concrete truck backing up to the A-frame and lance, trucks drive through the A-frame in most installations.

Fig. 2: The CryoCrete™ automated lN cooling system developed by Air liquide Industrial u.S. lP: (a) during injection testing and (b) just before cooling of a load of concrete in a truck

(a)

(b)



ACI member John Gajda is Senior Principal Engineer at CTlGroup, Skokie, Il. A licensed professional engineer, he received his MS and BS in material science engineering from Iowa State university. Gajda is Chair of ACI Committee 207, Mass Concrete, and a member of ACI Committee 301, Specifications for Concrete, and the ACI Committee on Awards for Papers.

Francisco Sumodjo is Senior Applications Specialist at Air liquide Industrial u.S. lP., union City, CA. He received his MS in chemical engineering from Pennsylvania State university and his MS in industrial and operations engineering from university of Michigan. Sumodjo develops industrial gas applications for many industries.

The cryogenic vessel is supported by a concrete pad and holds 6000 to 13,000 gal. (22,700 to 49,200 L) of LN. The actual size of the vessel depends on the distance from the LN production facility, the amount of concrete to be cooled, and the scheduling of the concrete placements. The pressure regulating system is built onto the cryogenic vessel. The automated injection system consists of a stainless steel lance mounted on an A-frame, which allows the lance to be extended in and out of the rotating drum of the concrete truck.

Prior to LN injection, the drum of the concrete truck must be at full rotation speed to disperse the concrete for efficient and uniform cooling. A reasonable estimate is that about 1.5 gal. of LN are needed to cool 1 yd3 of concrete by 1°F (about 13 L of LN are needed to cool 1 m3 of concrete by 1°C). Cooling rates are typically in the range of 2 to 5°F (1 to 3°C) per minute.

The actual required amount of LN and the cooling rate depend on a variety of factors. Damage to the concrete truck can occur if the LN is improperly sprayed into the drum (which can occur if the injection system isn’t automated or lacks a retractable lance), the cooling rate is too high, a partial load of concrete is cooled, or the drum is rotated too slowly.

References1. ACI Committee 207, “Cooling and Insulating Systems for Mass

Concrete (ACI 207.4R-05),” American Concrete Institute, Farmington Hills, MI, 2005, 15 pp.

2. Beaver, W., “Liquid Nitrogen for Concrete Cooling,” Concrete International, V. 26, No. 9, Sept. 2009, pp. 93-95.

3. Gajda, J.; Kaufman, A.; and Sumodjo, F., “Precooling Mass Concrete,” Concrete Construction, Aug. 2005. (available through www.massconcretehelp.com)

4. Murugesh, G., “Lightweight Concrete and the New Benicia-Martinez Bridge,” HPC Bridge Views, Issue 49, May/June 2008. (www.hpcbridgeviews.com/i49/Article1.asp)

5. Goodyear, D., “The Challenge of a Lifetime,” Concrete Construction, Oct. 2010.

6. Juenger, M.C.G.; Henna, J.; and Solt, S.M., “The Effects of Liquid Nitrogen on Concrete Properties (CTR Technical Report 0-5111-1),” Center for Transportation Research, University of Texas at Austin, Austin, TX, Oct. 2007, 120 pp. (www.utexas.edu/research/ctr/pdf_ reports/0_5111_1.pdf)

7. Juenger, M.C.G.; Solt, S.M.; and Hema, J., “Effects of Liquid Nitrogen on Concrete Properties,” ACI Materials Journal, V. 107, No. 2, Mar.-Apr. 2010, pp. 123-131.

8. Kaufman, A., “Special Job, Special Equipment,” Concrete Producer, Mar. 2007.


—Air Liquide Industrial U.S. LPwww.us.airliquide.com

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use of Siliceous Aggregates in Concrete— Texas Experience, Part 1Mineralogy, morphology, microstructure, and reactivity

by Hugh Wang and Elizabeth (Lisa) Lukefahr

The State of Texas is widely impacted by alkali-aggregate reactions (AAR) in various transportation structures. Throughout the years, with many research and investi-

gation programs, it has been identified that AAR in Texas is mainly attributed to alkali-silica reaction (ASR) in concrete.

In late 1998, the Texas Department of Transportation (TxDOT) initialized a comprehensive testing program using ASTM C1260, Standard Test Method for Potential Alkali Reactivity of Aggregates (Mortar-Bar Method), to evaluate ASR potential for all TxDOT-approved aggregate sources. Following the recommendations in Section X1.3.4 of ASTM C33, Standard Specification for Concrete Aggregates, mortar bars with 16-day expansions exceeding 0.20% indicated materials capable of potentially deleterious expansion. The testing program was repeated in 2009 and confirmed that about 80% of fine aggregate and 60% of coarse aggregate used in the state of Texas exhibited potentially deleterious expansion.

In response to the alarming scale of the potential ASR problem, TxDOT has aggressively sought to prevent ASR-related premature deterioration in new concrete structures. In March 2000, six strategies for concrete producers to address ASR were provided in the TxDOT Specification as Special Provisions to Item 421, Hydraulic Cement Concrete.1 Options 1 through 6 include the use of supplementary cementitious material (SCM), comprising Class F fly ash (F-FA), slag cement, silica fume (SF), Class C fly ash (C-FA), ultra-fine fly ash (UFFA), metakaolin, or modified Class F fly ash (MFFA); blended cement; or lithium nitrate admixture. The provisions contain the

cement replacement rate for each SCM type and dosage rate for lithium nitrate.

In 2004, two more provisions were added. Option 7 applies to concrete mixtures with portland cement only (no SCM), and it limits the total alkali contribution from the cement. This option originally limited the equivalent alkali content to 4.0 lb/yd3 (2.4 kg/m3), but the limit was lowered to 3.5 lb/yd3 (2.1 kg/m3) in 2009. Option 8, which is to be used if any deviation from Options 1 through 7 is deemed necessary, includes the testing of both the coarse and the fine aggregate separately in accordance with ASTM C1260, using 440 g (1 lb) of the proposed cementitious material in the same proportions as the intended mixture design. The expansion limit placed on the C1260 test results was 0.10%. In 2009, Option 8 was modified to use ASTM C1567, Standard Test Method for Determining the Potential Alkali-Silica Reactivity of Combinations of Cementitious Materials and Aggregate (Accelerated Mortar-Bar Method), and the limit on expansion was lowered to 0.08%. The special provisions to Item 421 are summarized in Table 1.

Although durability has improved significantly in recent years, some premature concrete deterioration has been reported. In mid-2011, TxDOT collaborated with the Cement Council of Texas (CCT) and the member companies of CCT to conduct an independent investigation on two cases of premature concrete deterioration. This article summarizes the findings on mineralogy, morphology, microstructures, and reactivity of aggregates used in the damaged concrete elements. A second article will focus on


ASR controllability and provide analyses of actual structures with surface cracking.

AggregatesAggregate samples were collected from the same sources

as the aggregates used for the fabrication of the precast concrete elements that exhibited premature deterioration. The aggregates were characterized with various techniques with the objectives to understand their mineralogy, morphology, microstructure, and reactivity.

Fine aggregateX-ray diffraction (XRD) analysis on the fine aggregate

revealed the presence of three major mineral phases: quartz/silica, calcite, and anorthite (a derivative mineral from the feldspar family). The XRD spectrum of the fine aggregate and its corresponding mineral phase identification are shown in Fig. 1.

The fine aggregate was also evaluated with the differential thermal analysis (DTA) method to detect its energy responses to changes in temperature. As its temperature was increased from ambient to 950°C (1742°F), the aggregate’s heat flow (HF) was evaluated to determine if it was under-going endothermic or exothermic reactions. At the same time, mass change was measured by thermogravimetric (TG) analysis. Figure 2 shows the HF and TG spectra of the fine aggregate. The HF spectrum shows three major thermal activities, with the first being an endothermic event at about 580°C (1076°F). The TG spectrum shows that this event is not accompanied by a significant mass change; this event is likely associated with a phase change in the fine aggregate.

Table 1: TxDOT SP 421—Current options for ASR control

Option Prescribed specification

1 Replace 20 to 35% of the portland cement with F-FA.

2 Replace 35 to 50% of the portland cement with slag cement or MFFA.

3Replace 35 to 50% of the portland cement with a combination of F-FA, slag cement, MFFA, uFFA, metakaolin,

or SF.

4 use Type IP or Type IS cement. (up to 10% of the cement can be replaced with F-FA, slag cement, or SF.)

5Replace 35 to 50% of the portland cement with a combination of F-FA and at least 6% SF, uFFA, or metakaolin.

However, no more than 35% may be C-FA, and no more than 10% may be SF.

6use lithium nitrate admixture at a minimum dosage determined by testing conducted in accordance with

Tex-471-A, lithium Dosage Determination using Accelerated Mortar Bar Testing.2

7When using cement only, ensure that the total alkali contribution from the cement in the concrete does not exceed

3.5 lb/yd3 (2.1 kg/m3).

8

For any deviations from Options 1 to 7, perform the following:

Test both coarse and fine aggregate separately in accordance with ASTM C1567, demonstrating that the test result

for each aggregate does not exceed 0.08% expansion at 14 days.

Fig. 1: XRD spectrum of fine aggregate

Fig. 2: heat flow and TG spectra of fine aggregate (°F = 1.8 × °C + 32)


A second intensive endothermic event occurs at around 810°C (1490°F). In this case, the TG spectrum shows a strong mass loss; this event is likely the result of the evaporation of carbon dioxide from the decomposition of the calcite phase in the aggregate. A third exothermic event occurs at around 890°C (1634°F). The TG spectrum shows no mass change associated with this event; this event is likely related to the re-crystallization of amorphous phase(s) in the fine aggregate.

Petrographic examinations indicated that the most common minerals are quartzite, feldspar, sandstone, siltstone, and calcite (Fig. 3). In general, the minerals in the fine aggregate can be classified in two major categories: siliceous/silicate minerals and calcite. The most notable characteristic is the inclusion of chalcedony (fibrous silica) particles, either in isolation or agglomerations within calcite matrixes (shown in Fig. 3(c) and (d)). It’s well known that chalcedony is highly alkali-reactive.

Coarse aggregateThe coarse aggregate was evaluated

with the same techniques as used for fine aggregates. Figure 4 shows the XRD spectrum of the coarse aggregate. The XRD analysis revealed that the coarse aggregate predominately contains calcite. A minor silica phase is also present. To better identify the minor components in the coarse aggregate, acid extraction was used to remove the calcite from the sample. The XRD spectrum of the acid-extracted residue shows only a silica phase (Fig. 4).

Figure 5 shows the HF and TG spectra of the coarse aggregate. Only one thermal event was registered—at about 920°C (1688°F). This event was accompanied by a huge mass loss; it’s likely due to the evaporation of carbon dioxide from calcite decomposition.

Figure 6 shows the microstructure of the coarse aggregate. Figure 6(a) and (b) are the general view of the calcite, showing both isolated chalcedony particles and agglomerated chalcedony clusters embedded in the matrix.

Fig. 3: Microstructures of fine aggregate samples: (a) quartzite and feldspar at 50× magnification; (b) sandstone, at 50×; (c) limestone with embedded chalcedony, at 50×; and (d) limestone with embedded chalcedony, at 200×

Fig. 4: XRD spectra of coarse aggregate and its residue after acid extraction

Fig. 5: heat flow and TG spectra of coarse aggregate (°F = 1.8 × °C + 32)

(d)(c)

(a) (b)


Figure 6(c) shows the particle size distribution of the residue material after acid extraction. This distribution shows that the chalcedony clusters that had once been embedded in the calcite matrix broke down to particles during acid extraction. This characteristic is important with respect to understanding and explaining the ASR potential of coarse aggregate. Figure 6(d) shows the microstructure of a particle left after acid extraction, showing the fibrous morphology typical of chalcedony.

Aggregate ReactivityASR test methods

There are many testing methods for evaluating the reactivity of aggregates, and each method has its pros and cons. ASTM C289, Standard Test Method for Potential Alkali-Silica Reactivity of Aggregates (Chemical Method), was developed in the early 1950s. This is a compositional test method to determine the alkali-soluble silica content in an aggregate. Unfortunately, it has proven to be very difficult to relate the amount of alkali-soluble silica in an aggregate to the concrete performance in the

Fig. 6: Microstructure of coarse aggregate: (a) limestone with embedded chalcedony, at 50× magnification; (b) limestone with embedded chalcedony, at 50×; (c) acid insoluble residue, at 50×; and (d) acid insoluble particle showing fibrous structure of chalcedony, at 200×

(d)(c)

(a) (b)

field. ASTM C227, Standard Test Method for Potential Alkali Reactivity of Cement-Aggregate Combinations (Mortar-Bar Method), was one of the earliest performance-based methods to evaluate aggregate reactivity. However, researchers later found that the method has technical flaws related to the specimen storage condition, moisture distribution issues, and alkali leaching problems.3 The test results are thus highly unreliable. Because the method also requires a lengthy testing period, it’s unattractive for practical use.

A rapid ASR test method, ASTM C1260, was developed in the late 1980s. ASTM C1260 is largely based on ASTM C227, but the mortar bars are stored in an alkali solution at 80°C (176°F) rather than over water at 38°C (100°F). Results are available 16 days after the specimen is made, but it’s generally believed that this method overestimates the ASR potential of an aggregate. In the mid-1990s, ASTM C1293, Standard Test Method for Determination of Length Change of Concrete Due to Alkali-Silica Reaction, was developed. It’s widely

accepted that this method is the most realistic and reliable test method for ASR determination. It also has drawbacks, however, including a long testing period and the potential for leaching of alkalis from the concrete test specimens.

There is consensus in the technical community that ASTM C1260 can be used to identify deleterious and innocuous aggregates. If ASTM C1260 results are inconclusive, ASTM C1293 is recommended for final determination.

In 2000, TxDOT sponsored a comprehensive research program on ASR at the Center for Transportation, the University of Texas at Austin, Austin, TX. The program was aimed to make recommendations for improving the durability of the state’s transporta-tion structures. Many of the provisions adopted in the state’s Special Provisions to Item 421 were based on the research work from this program.4

ASR potential in tested aggregatesIn the comprehensive research

program, ASR potential was evaluated using ASTM C1260. Figure 7 shows expansion results of the mortar bars made with both fine and coarse aggregates. The expansion of the bars made with fine aggregate averaged 0.18%. Based on recommendations in an appendix to ASTM C33, the ASR potential of the fine aggregate can be classified as “inconclusive.” However, the average expansion of the bars made with coarse aggregate, which contains predominately calcite mineral, was 0.22%. The ASR potential for the coarse aggregate therefore falls into the category of “indicative of potentially deleterious expansion.”

The results are somewhat illogical from a mineralogical aspect, as the fine aggregate, predominately silica/silicate minerals with some calcite, should have higher ASR potential, while the coarse aggregate, predomi-nately calcite, should have lower ASR potential. However, the differences of expansion behavior cannot be explained purely from a mineralogical aspect.


Fig. 7: Mortar bar expansion of fine and coarse aggregates tested per ASTM C1260

Fig. 9: Microstructure of mortar bar made with coarse aggregate after ASTM C1260 testing: (a) and (b) at 50× magnification; and (c) at 200×

Petrographic assessment of tested aggregates

To understand the change of aggregate microstructure after ASTM C1260 tests, petrographic evaluations were conducted on the mortar bars. Particular focus was placed on the condition and extent of ASR reaction sites, voids, and cracks.

Figure 8 shows the microstructure of the mortar bar made with fine aggregate and examined after the ASTM C1260 test. Extensive cracking is visible in the paste matrix, with most of the cracks originating from reaction sites linked to chalcedony particles. In some cases, multiple cracks originated from one reaction site (Fig. 8(b)). The cracks and other voids are partially or fully filled with deposit materials (Fig. 8(c)), presumably due to the migration of ASR reaction products.

Figure 9 shows the microstructure of the mortar bars made with coarse aggregate and examined after ASTM C1260 tests. The amount of cracks and the propagated distance of the cracking system are much more severe than in the bars made with fine aggregate.

Reactive material size The common microscopic feature

of the bars made with fine and coarse aggregates was the massive reactivity of chalcedony mineral embedded in the calcite rock. While the fine aggregate may contain other reactive siliceous materials, only chalcedony was positively identified in association with the reactive sites and cracks in the mortar specimens.

The differences in expansion and microstructure between coarse and fine aggregates may be associated with two factors: 1) the coarse aggregate has more reactive chalcedony than the fine aggregate; and 2) the coarse aggregate has larger chalcedony deposits (either as individual particles or agglomerated clusters) than the fine aggregate.

Since the classic research by Stanton,5 it’s been repeatedly shown that the particle size of alkali-reactive siliceous material has a significant impact on ASR expansion. A large amount of ASR

Fig. 8: Microstructure of mortar bar made with fine aggregate and examined after ASTM C1260 testing: (a) cracking of paste, at 50× magnification; (b) multiple cracks originate from a single reaction site, at 100×; and (c) cracks with deposits, at 200×

(b) (b)

(a)(a)

(c) (c)

0.00

0.05

0.10

0.15

0.20

0.25

0 2 4 6 8 10 12 14

Time (days)E

xpan

sion

(%)

Fine aggregate Coarse aggregate

Potentially deleterious expansion

Innocuous behavior


ACI member Hugh Wang is the Director of the CEMEX Technical Center, Riverview, Fl. He received his PhD in material science from the university of Calgary, Calgary, AB, Canada, and his MSc in cement chemistry and process technology from Wuhan university of Technology, Wuhan, China. He has been working in the cement, concrete,

and chemical admixture industries for over 21 years.

Elizabeth (Lisa) Lukefahr is the Manager of Rigid Pavement and Concrete Materials for the Texas Department of Transporation (TxDOT), Austin, TX. She received her BS in mechanical engineering from the university of Texas at Austin, Austin, TX, in 1989, and her BA in English, also from the university of Texas, in 1990. Her career with TxDOT has included

assignments in the Department’s Research Section, Pavements Section of the Design Division. lukefahr is TxDOT’s voting member on ASTM Committee C01, Cement, and a panel member of NCHRP 18-11 on “The Relationship of Processing Additions in Cement Manufacturing to Concrete Durability.” She was appointed to her current position in 2004 and currently oversees all Cement and Concrete laboratory operations.

reactive material concentrated at a single site will have a much greater effect than the same amount of gel dispersed throughout the matrix. The smaller ASR reactive material tends to form calcium-doped nonexpansive ASR gel, whereas large ASR reactive material tends to form expansive ASR gel.6

In the study described in Reference 4, some coarse aggregates were shown to be acceptable when tested per ASTM C1260, yet shown to be unacceptable when tested per ASTM C1293. This behavior may well be related to the gradation requirements for the two test standards (Table 2 and 3). While ASTM C1260 requires a significant size reduction of coarse aggregate particles, ASTM C1293 does not require aggregate size reduction. Sample preparation for ASTM C1260 would therefore be expected to produce smaller ASR reactive materials than ASTM C1293.

ConclusionsEvaluation of test specimens produced using aggregates

from the same sources as used in prematurely degraded concrete elements shows that ASR is the cause of the degradation. Although both fine and coarse aggregate samples caused ASR damage, the severity of ASR in specimens made with coarse aggregate is higher than that in the fine aggregate. In both cases, damage was traced to chalcedony particles embedded in calcite matrixes in the aggregate particles.

The embedded chalcedony particles in the fine aggregate samples are smaller than the chalcedony particles in the calcite matrix of the coarse aggregate. The size difference of chalcedony particles is the likely reason for the difference in expansion.

Cracks and voids in the specimens clearly showed evidence of deposit materials; this is largely from the migration of ASR gel to the voids through the cracking system, originated from ASR reaction sites.

Table 2:Aggregate size gradation requirements for ASTM C1260 tests

Sieve size

Mass, %Passing Retained on

4.75 mm (No. 4) 2.36 mm (No. 8) 10

2.36 mm (No. 8) 1.18 mm (No. 16) 25

1.18 mm (No. 16) 600 μm (No. 30) 25

600 μm (No. 30) 300 μm (No. 50) 25

300 μm (No. 50) 150 μm (No. 100) 15

Table 3: Aggregate size gradation requirements for ASTM C1293 tests

Sieve size

Mass, %Passing Retained on

19.0 mm (0.75 in.) 12.5 mm (0.5 in.) 33

12.5 mm (0.5 in.) 9.5 mm (0.38 in.) 33

9.5 mm (0.38 in.) 4.75 mm (No. 4) 33

References1. Special Provision to Item 421, Portland Cement Concrete, Texas

Department of Transportation, Austin, TX.2. “Test Procedure for Lithium Dosage Determination Using

Accelerated Mortar Bar Testing (TEX-471-A),” Texas Department of Transportation, Austin, TX, July 2009, 3 pp.

3. Rogers, C.A., and Hooton, R.D., “Reduction in Mortar and Concrete Expansion with Reactive Aggregates due to Alkali Leaching,” Cement, Concrete and Aggregates,” V. 13, No. 1, 1991, pp. 42-49.

4. Folliard, K.J.; Barborak, R.; Drimalas, T.; Du, L.; Garber, S.; Ideker, J.; Ley, T.; Williams, S.; Juenger, M.; Fournier, B.; and Thomas, M.D.A., “Preventing ASR/DEF in New Concrete: Final Report,” Center for Transportation, University of Texas at Austin, Austin, TX, 2006, 254 pp.

5. Stanton, T.E., “The Expansion of Concrete through Reaction between Cement and Aggregate,” Proceedings, American Society of Civil Engineers, V. 66, 1940, pp. 1781-1811.

6. Wang, H., and Gillott, J.E., “Mechanism of Alkali-Silica Reaction and the Significance of Calcium Hydroxide,” Cement and Concrete Research, V. 21, No. 4, July 1991, pp. 647-654.


Note: Additional information on the ASTM standards discussed in this article can be found at www.astm.org.


Products &

PracticeDeWALT Adjustable Depth Setter and Dust Collector

Designed to aid in overhead applications, DeWALT’s Adjustable Depth Setter and Dust Collector work together alongside DeWALT SDS Plus drill bits to reduce downtime for the professional. The Adjustable Depth Setter provides an accurate depth stop for setting the most commonly used drop-in anchors (1/4, 3/8, and 1/2 in. [6, 10, and 13 mm]). The Dust Collector is a flexible cup that fits over the Depth Setter sleeve and flushes tightly against the application material, creating a collection area for dust and debris.

—DeWALTwww.dewalt.com

Phoenix 7500 Slipform CurberThe Phoenix 7500 slipform curb machine can easily

negotiate tight corners in grading and placing and, with the flip of a switch, automatically backs down a string line. Front dual rotary actuators allow 90-degree turns with the single-operator machine. It has a placing speed of up to 50 ft (15 m) per minute and can travel up to 200 ft (61 m) per minute. Additionally, it is outfitted with a TopCon grade and slope controller, advanced controls and sensors, four-wheel drive, and auto rear steering.

—Phoenix Curb Machineswww.phoenixcurbmachines.com

Ultra Tech Induction-Hardened PipingMany concrete pumping contractors are specifying a type of induction-hardened pipe designed to stand up to abrasion,

especially when working on skyscrapers or other projects that involve transporting concrete long distances. By being extremely hard on the inside, the pipe resists abrasion from rough concrete mixtures, but the softer outer wall provides the required toughness to contain the high pressure and mechanical loading the pipeline will encounter. Construction Forms, Inc. (ConForms), is a leading provider of abrasion-resistant piping systems and produces Ultra Tech piping, which is engineered to last up to five times longer than mild steel piping. Ultra Tech pipes were selected for use in the construction of the Shangri-La Hotel and Condominium Tower in Toronto, ON, Canada, by the Amherst Group, which was in charge of concrete pumping for the project. To supply 70 stories worth of concrete for the building, a system of lay-down and vertical pipes was used. Truck-mounted boom pumps supplied concrete from the foundation up to the fifth floor, at which point the Ultra Tech pipes were installed with a stationary pump. Construction from the fifth floor to the 68th floor was completed in 14 months, and there were never any delays caused by failures in the pumping system.

—Construction Forms, Inc.www.conforms.com

Information on the items reported in “Products & Practice” is furnished by the product manufacturers, suppliers, or developers who are respon-sible for the accuracy of the information. Also, the descriptions of these items do not represent endorsement by this magazine, by the American Concrete Institute, or any of its staff. They are published here simply as a service to our readers.


Products & Practice

ToolSelect.comToolSelect.com is an unbiased

power tool comparison Web site that aims to help consumers find the best power tool for the job. The site does not sell tools but, rather, relies on expert and consumer reviews and statistics on a vast collection of power tools. The site hosts numerous power tool videos that include product demonstrations, manufacturer interviews, and reviews from do-it-yourselfers and industry professionals. The site has a Feature Finder that allows visitors to search for a specific tool based on exact specifications. Users who create a profile or log in using their Facebook account can also contribute content through the site’s discussion boards, surveys, and polls, and by submitting their own product reviews. Additionally, users who provide quality content can earn points to be redeemed for rewards, including apparel, accessories, and tools.

—ToolSelectwww.toolselect.com

E-Z Drill Aids California Highway ProjectWhen a 22 mile (35 km) stretch of Interstate 210 between

Pasadena and Glendora, CA, needed a major overhaul, the California Department of Transportation hired J McLoughlin Engineering, Inc., to facilitate the project. Due to high traffic, work on the highway could only be performed between 10 p.m. and 5 a.m., and the contractor was only given 140 working days to complete the project. Like most repaving jobs, the work was completed in sections at various locations along the stretch. The patching work started by cutting and removing a section. The crew then brought in E-Z Drill concrete drills to drill holes where the dowel bars would be placed. For the project, J McLoughlin looked to its fleet of E-Z Drill slab rider drills, using a total of eight drills in varying gang sizes. The primary drill used was the Model 210B-2 SRA, a two-gang slab rider unit, of which four units were used at all times. Over the course of the project, an estimated 200,000 holes were drilled. The company purchased extra drills in the event of equipment failure, but none of the backups were required and the project was completed on time.

—E-Z Drillwww.ezdrill.com

Düraamen Seamless Flooring SystemsDüraamen offers several flooring systems designed to enhance the functionality, productivity, safety, and aesthetics

of a facility. Seamless flooring facilities provide a cleaner and safer work environment by eliminating a potential hiding place and breeding ground for bacteria and other contaminants that can threaten a facility’s regulatory compliance. These flooring systems are designed for fast installation and return to service and long-lasting performance. They are available in several different thicknesses and chemical compositions and come in a variety of colors to ensure ideal performance and appearance.

—Düraamen Engineered Products, Inc.www.duraamen.com

Web Notes


Products & Practice

Roark’s Formulas for Stress and Strain, Eighth Editionby Warren C. Young, Richard G. Budynas, and Ali M. Sadegh

The fully revised eighth edition of Roark’s Formulas for Stress and Strain provides accurate and thorough tabulated formulations that can be applied to the stress analysis of a comprehensive range of structural components. All equations and diagrams of structural properties are presented in an easy-to-use, thumb-through format. This updated edition contains new chapters on fatigue and fracture mechanics, stresses in fasteners and joints, composite materials, and biomechanics. Several chapters have been expanded and new topics have been added. Each chapter now concludes with a summary of tables and formulas for ease of reference. Topics covered include behavior of bodies under stress; tension, compression, shear, and combined stress; bending of curved beams; columns and other compression members; elastic stability; and stresses in fasteners and joints.

McGraw Hill, Web site: www.mhprofessional.comprice: $125; 1072 pp.; ISBN 9780071742474

Interim Guide for Optimum Joint Performance of Concrete Pavements

The purpose of this guide is to help practitioners understand how to optimize concrete joint

performance through the identification, mitigation, and prevention of joint deterioration. Research is underway to identify the causes of and possible preventive measures for premature joint deterioration. A current project is Federal Highway Administration Transportation Pooled Fund Study TPF 5(224): Investigation of Jointed Plain Concrete Pavement Deterioration at Joints and the Potential of Deicing Chemicals, led by the Iowa Department of Transportation and done in collaboration with the National Concrete Pavement Technology Center (CP Tech Center) at Iowa State University, Michigan Technological University, and Purdue University, with sponsorship from state departments of transportation from across the Midwest. The CP Tech Center has been assisting the project by synthesizing and supplementing the research performed to date using data provided by local authorities and laboratory testing, which has resulted in significant knowledge about joint deterioration. Instead of waiting for the research to be completed, the CP Tech Center has developed this interim guide under TPF 5(224) to help practitioners access the latest knowledge and implement proven techniques for identifying, mitigating, and reducing the risk of premature joint damage. The guide can be downloaded as a PDF for free at publications.iowa.gov/11896.

—National Concrete Pavement Technology Centerwww.cptechcenter.org

HYDRO ACTIVE GroutsThe HYDRO ACTIVE® Grouts line has been reformulated to enhance performance, durability, mechanical

properties, and ease of use. All-new resins have improved cell structure with increased strength, resulting in a tougher and more resilient cured project. The one-component water reactive and waterproofing resins have faster and higher expansion, making waterproofing injections faster and more efficient. The grouts retain their closed-cell foam structure, ensuring durable waterproofing results with a single injection.

—De Neef Construction Chemicalswww.deneef.com

Products&ServiceLiterature&Videos

Book Notes


Product

ShowcaseGrinding and Cutting Equipment

Metabo “Instant Brake” GrindersIdeal for heavy-duty grinding and cutting applications,

Metabo’s WEPBA14-125 Quick and WEPBA14-150 Quick angle grinders both feature a 12.2 A motor and 1400 watts of power. The WEPBA14-125 Quick offers a no-load speed of 10,000 rpm and a 5 in. (127 mm) maximum wheel diameter, while the WEPBA14-150 Quick provides 9000 rpm and a 6 in. (152 mm) maximum wheel diameter. They both offer a mechanical brake system that stops a grinding disc in 2 seconds or less; the system was tested to 50,000 cycles with no failures. The tools also feature Metabo’s auto-balance technology to reduce vibration and the Metabo “S” automatic safety clip clutch to help prevent kickback.

—Metabo Corporationwww.metabo.us

DG7 Surface GrinderThe 55 lb (25 kg) DG7 surface grinder is a versatile and easy-to-use high-speed

surface grinder. The 2300-watt grinder can use a variety of 7 in. (178 mm) diamond segment discs to perform many types of grinding and surface preparation, and can perform small polishing jobs when used with General Equipment’s Pro Polish™ attachments. It also allows the operator to work in an upright position and features a 2.25 in. (57 mm) diameter vacuum connection port for dust control.

—General Equipment Companywww.generalequip.com

Facet Diamond ToolsLythic Solutions’™ Facet Diamond™

tools are ceramic-bond diamond tools designed to improve upon and replace medium-grit metal-bond tools. Ceramic-bond tools wear slower than metal bonds and grind more evenly, preventing unwanted deep scratches. They do not build or store heat and therefore do not expand, which can cause metal-bond tools to lose their grip on diamond chunks. The Facet Diamond tools also use a high-grade synthetic diamond treated for longer service life and processed for fewer fractures.

—Lythic Solutions, Inc.www.lythic.net

Bosch Diamond Cup WheelsBosch introduced a new lineup of diamond cup

wheels ranging in size from 4 to 7 in. (102 to 178 mm), each with an increased height of 1.5 in. (38 mm) for better dust collection. The wheels are offered in two styles: a double-row design for more aggressive material removal of high spots, and a turbo cup wheel that creates a smooth finish. They don’t require a spanner wrench or other tools for attachment to the grinder and are designed to meet the requirements for a variety of grinding tools, particularly angle grinder specifications.

—Bosch Tool Corp.www.boschtool.com


Product Showcase

Husqvarna DM 220The DM 220 is the first drilling machine with an

electronic system for accurate positioning. The system uses an LED indicator to show when the machine is in a vertical or horizontal position, and can be calibrated to help guide the operator during angle drilling. The machine is also equipped with SmartStart™, which reduces drill speed to ease starting a hole, and Softstart™, an electronic current limiter designed to create a smooth start.

—Husqvarna www.husqvarna.com

Brokk 800 Demolition Machine

The Brokk 800 Demolition Machine is more than twice the size of Brokk’s previous largest model and is the biggest on the market. It is available in two models: the 800S, which has a maximum reach of 30 ft (9.1 m); and the 800P, which has a reach of 31.5 ft (9.6 m), 360-degree rotation, and protection against heat when working in challenging process applications. Both 800 units weigh over 24,000 lb (10,900 kg) and can carry attachments up to 2465 lb (1120 kg). Brokk also offers eight demolition machine models of varying size and lift capacities, the smallest being the Brokk 50 at 1100 lb (500 kg).

—Brokk ABwww.brokk.com

AS170 Brick and Mortar SawThe AS170 is a handheld, versatile brick and mortar

saw. It will cut square openings without overcutting or stitch drilling, and its forward-facing blades allow clear visibility when precision is required. It is the only handheld saw that can cut to a depth of 4.75 in. (120 mm). A variety of blades are available for a number of purposes, including caulk and mortar removal and restoration projects, and all are able to be resharpened.

—Arbortechwww.arbortechusa.com

Blastrac BG-250MKIIBlastrac’s BG-250MKII grinding machine is

ideal for applications requiring heavy-duty surface preparation of small to medium jobs. Its compact size allows it to grind closer to the wall than older models. It can be purchased as a gas or electric model and, when used with a Blastrac dust collector, offers nearly dust-free operation.

—Blastrac, NAwww.blastrac.com


Calls for

PapersACI Materials Journal

Publication: The ACI Materials Journal is accepting manuscripts on concrete and cementitious materials.

Solicited: Manuscripts focused on ultra-high-perfor-mance fiber-reinforced concrete composites, advanced cementitious material technologies, or research related to enhancing the durability and resilience of concrete construction are invited. Manuscripts should reflect orig inal research and technological advances on the state of the art in materials design and behavior.

Requirements: To be considered for publication, manuscripts must be submitted via the ACI manuscript submission site: http://mc.manuscriptcentral.com/aci.

Deadline: Open-ended.Contact: For assistance, contact Daniela Bedward,

ACI Publishing Assistant, telephone: (248) 848-3753; e-mail: [email protected].

Historic Concrete StructuresMeeting: Technical session on “Historic Concrete

Structures” at the ACI Spring 2013 Convention, April 14-18, 2013, in Minneapolis, MN; sponsored by ACI Committee 120, History of Concrete.

Solicited: Papers and presentations related to the history of concrete structures—such as antiquated structural systems, unique applications of concrete, and the con-structors and designers of historic concrete structures— are invited. Each speaker will deliver a 20- to 30-minute presentation during the session.

Requirements: 1) Presentation title; 2) author/speaker name(s), title, affiliation, and contact information; and 3) abstract of 500 words maximum.

Deadline: Abstracts are due by July 15, 2012. Send to: Kimberly Kramer, Kansas State University,

230 Seaton Hall, Manhattan, KS 66506; e-mail: [email protected]; telephone: (785) 532-5964; fax: (785) 532-3556.

Green CementsMeeting: Technical session on “Green Cements” during

the ACI Spring 2013 Convention, April 14-18, 2013, in Minneapolis, MN; sponsored by ACI Committees 232, Fly Ash and Natural Pozzolans in Concrete; 236, Material Science of Concrete; 363, High-Strength Concrete; and 130E, Design/Specifications/Codes/Regulations.

Solicited: Papers are invited for a two-part session and a special publication on the benefits of binders produced with significantly reduced, little, or no process energy; with a small carbon footprint; composed of recycled and/or renewable resources; and which have minimal environ-mental impact. Preference will be given to presentations

considering activated fly ash, activated slag, or geopolymer cements; ASTM C1600 rapid hardening hydraulic cements; ASTM C1157 performance cements; ASTM C595 cements; concrete with high amounts of supplementary cementi-tious material; and mortars, grouts, and masonry unit production with green cements.

Requirements: 1) Presentation title; 2) author/speaker name(s), job title, affiliation, and contact information; and 3) abstract of 500 words maximum.

Deadlines: Abstracts are due by July 16, 2012; final papers are due by October 1, 2012.

Send to: James Hicks, CeraTech, Inc., 3501 Brehms Lane, Ste. D, Baltimore, MD 21213; telephone: (936) 697-2893; fax: (443) 524-4410; e-mail: [email protected].

Sustainable Construction Materials and Technologies

Meeting: Third International Conference on Sustain-able Construction Materials and Technologies (SCMT3), August 18-22, 2013, Kyoto, Japan; sponsored by Coventry University, University of Wisconsin-Milwaukee Center for By-products Utilization, and Japan Concrete Institute; cosponsored by ACI, ASCE, and RILEM.

Solicited: The main conference themes are sustainable construction materials and structures, durability of construc-tion materials, and maintenance and life-cycle management of structures. Papers presented at SCMT3 will be selected for publication in the ASCE Journal of Materials in Civil Engineer-ing. A new competition is planned for SCMT3, in which the newest technologies with the greatest potential will be put forward to a panel of contractors to carry out site trials.

Requirements: Abstracts of 200 to 300 words on all types of construction materials, including timber, steel, and concrete, are invited. Submit abstracts at www.scmt.org.uk.

Deadline: Abstracts are due by July 27, 2012.Contact: Peter Claisse, e-mail: [email protected];

or Tarun Naik, e-mail: [email protected].

Research in ProgressMeeting: Two 2-hour technical sessions on “Research in

Progress” during the ACI 2012 Fall Convention, October 21-25, 2012, in Toronto, ON, Canada; sponsored by ACI Committee 123, Research and Current Developments.

Solicited: Short presentations (typically 12 to 15 min utes) are invited in the area of concrete structures and materials related to any aspect of an ongoing research program highlighting the overall scope of the research, methods of investigation, test procedures, results, and conclusions to date. The purpose of this session is to offer authors/speakers an open forum for the presentation of


Calls for Papers

Calls for Papers: Submission GuidelinesWe recommend that notices of calls for papers be submitted to Concrete International at least 9 months (or sooner) prior to the prospective sessions. This timetable generally allows publishing of the notification in three issues of the magazine. Please send meeting information, papers/presentations being solicited, abstract requirements, and deadline, along with full contact information to: Keith A. Tosolt, Managing Editor, Concrete International, P.O. Box 9094, Farmington Hills, MI 48333-9094; fax: (248) 848-3150; e-mail: [email protected]. Visit www.callforpapers.concrete.org for more information.

recent technical information that does not fit into other sessions scheduled for this convention.

Requirements: 1) Presentation title; 2) author/speaker name(s), job title, affiliation, and contact information; and 3) abstract of 250 words maximum. One relevant figure may be included.

Deadline: Abstracts must be submitted electronically no later than July 31, 2012. Authors/speakers will be notified of the review decision for acceptance by August 14, 2012.

Send to: Thomas Schumacher, University of Delaware, telephone: (302) 831-4559, e-mail: [email protected]; and Kerry Hall, University of Southern Indiana, telephone: (812) 228-5074, e-mail: [email protected].

Open Paper SessionMeeting: A 2-hour technical session titled “Open Paper

Session” during the ACI 2012 Fall Convention October 21-25, 2012, in Toronto, ON, Canada; sponsored by ACI Committee 123, Research and Current Developments.

Solicited: Previously unpublished information from completed studies on any aspect of structural analysis, concrete materials science, structural design, construction, manufacturing, use, and maintenance of concrete structures and products. The purpose of this session is to offer authors/ speakers an open forum for presentation of recent technical information that does not fit into other sessions scheduled for this convention. Typical presentation time is 18 to 20 minutes.

Requirements: 1) Presentation title; 2) author/speaker name(s), job title, affiliation, and contact information; and 3) abstract of 250 words maximum. One relevant figure may be included.

Deadlines: Abstracts must be submitted electronically no later than July 31, 2012, to both the moderators. Authors/speakers will be notified of the review decision for accep-tance by August 14, 2012.

Send to: Sulapha Peethamparan, Department of Civil & Env. Engineering, Clarkson University, Potsdam, NY; telephone: (315) 268-4435; e-mail: [email protected]; and Jinying Zhu, The University of Texas at Austin, Austin, TX; telephone: (512) 232-5502; e-mail: [email protected].

Transportation Research RecordMeeting: Transportation Research Board (TRB) 92nd

Annual Meeting, January 13-17, 2013, in Washington, DC, and the Transportation Research Record: Journal of the Trans -portation Research Board (TRR).

Solicited: While papers addressing any relevant aspect of transportation research will be considered, some TRB

committees are soliciting papers in specific subject areas to help potential authors identify topics for their papers. The calls for papers can be sorted by major subject area, title, or sponsoring committee.

Requirements: Solicited and unsolicited papers for presentation and/or publication as part of the 92nd TRB Annual Meeting and the TRR must be submitted in PDF format directly to TRB via the paper submission Web site. For more information, visit www.TRB.org/AnnualMeeting.

Deadline: Paper submissions are due by August 1, 2012.

Performance of Concrete Bridges in Recent Earthquakes

Meeting: Technical session on “Performance of Concrete Bridges in Recent Earthquakes” at the ACI Spring 2013 Convention, April 14-18, 2013, in Minneapolis, MN; sponsored by ACI Committee 341, Earthquake-Resistant Concrete Bridges.

Solicited: Papers are invited on the performance of concrete bridges in recent earthquakes, such as the 2010 Chile, the 2011 Christchurch, and the 2011 Tohoku earth-quakes. Topics will include damage assessment, evaluation techniques and analytical methods, and identification of good and poor practices in seismic design and detailing of concrete bridges.

Requirements: 1) Presentation title; 2) author/speaker name(s), title, affiliation, and contact information; and 3) abstract of 300 to 500 words.

Deadline: Abstracts are due by August 15, 2012.Send to: Nadim Wehbe, South Dakota State University,

e-mail: [email protected].

Design and Implementation of Long Span Bridges and Roofs

Meeting: International Association for Bridge and Structural Engineering (IABSE) Symposium on Long Span Bridges and Roofs—Development, Design, and Implemen-tation, September 24-27, 2013, in Kolkata, India; organized by the Indian Group of IABSE.

Solicited: Presentations are invited on the latest achieve-ments and developments in research, design, construction, monitoring, maintenance, and performance of long span infrastructure works.

Requirements: Authors can submit a 200- to 300-word abstract in English, without illustrations, online at www.iabse.org/Kolkata2013.

Deadline: Abstracts are due by August 30, 2012.Contact: Indian Group of IABSE, telephone: +91-11-

2378-2923, +91-11-2338-6724; fax: +91-11-2338-8132.


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____ SP285CD.CI $73.50 ($44.00 ACI members)


What’s

NewConcrete Construction and Structural Evaluation: A Symposium Honoring Dov Kaminetzky, 2012, CD-ROM—SP-285

This CD-ROM contains 14 papers sponsored by ACI Committees 347, 350, 364, and 437. The papers represent a broad range of topics, including: concrete mixture design, design and construction, construction failures, formwork in concrete design, and more.

Order Code: SP285CD.CI Price: $73.50 (ACI members $44.00)

What’sComing

Summer 2012

Report on the Use of Raw or Processed Natural Pozzolans in Concrete—ACI 232.1R-12

Guide to Cast-in-Place Architectural Concrete Practice—ACI 303R-12

Guide for the Design and Construction of Durable Concrete Parking Structures— ACI 362.1R-12

Code Requirements for Design and Construction of Concrete Structures for the Containment of Refrigerated Liquefied Gases and Commentary—ACI 376-11

ACI Design Handbook—SP-17(2011)

You’ll never have to wait for ACI’s Online Bookstore to open. Our collection of over 400 standards, technical reports, special publications, and industry favorites is always open—waiting for you!

Additionally, you can download many of ACI’s publications immediately!

ACI’s online bookstore— it’s always open! www.concrete.org


July3-5

Structural Faults + Repair 2012, Edinburgh, Scotland, UK www.structuralfaultsandrepair.com

8-1210th International Conference on

Concrete Pavements, Quebec City, QC, Canada www.concretepavements.org/10thiccp

6th International Conference on Bridge Maintenance, Safety, and Management, Lake Maggiore, Italy www.iabmas2012.org

9-11Concrete in the Low Carbon Era,

Dundee, Scotland, UK www.ctucongress.co.uk

22-259th fib International PhD

Symposium in Civil Engineering, Karlsruhe, Germanyfib-phd.imb.kit.edu

22-28ICCE-20, Beijing, China

www.icce-nano.org

26-29ASCC CEO Forum 2012, Couer

d’Alene, IDwww.ascconline.org

August29-31

Our World in Concrete and Structures, Singaporewww.cipremier.com/page.php?479

September3-5

3rd International Conference on Concrete Repair, Rehabilitation, and Retrofitting, Cape Town, South Africawww.iccrrr.uct.ac.za

6-7CSDA Fall Meetings, Rosemont, IL

www.csda.org

17-18Cement and Concrete Science

2012, Belfast, UKwww.qub.ac.uk/sites/ccs2012

UPCOMING ACI CONVENTIONS2012 — October 21-25, Sheraton Centre, Toronto, ON, Canada.

2013 — April 14-18, Hilton & Minneapolis Convention Center, Minneapolis, MN.

2013 — October 20-24, Hyatt Regency & Phoenix Convention Center, Phoenix, AZ.

2014 — March 23-27, Grand Sierra Resort, Reno, NV.

For additional information, contact: Event Services, ACI, P.O. Box 9094 Farmington Hills, MI 48333-9094

Telephone: (248) 848-3795 • E-mail: [email protected]


Accelerated Pavement Testing, Davis, CAwww.ucprc.ucdavis.edu/APT2012

18th IABSE Congress, Seoul, South Koreawww.iabse.org/Seoul2012

8th RILEM International Sympo-sium on Fibre Reinforced Concrete, Guimarães, Portugalwww.befib2012.civil.uminho.pt

20-23ASCC Annual Conference,

Chicago, ILwww.ascconline.org


Problematic Soils, Wuhan, Chinawww.cipremier.com/page.php?487

24-2815th World Conference on

Earthquake Engineering, Lisbon, Portugalwww.15wcee.org

September/October29-2

PCI Annual Convention & Exhibition and National Bridge Conference, Nashville, TNwww.pci.org

October3-5

7th Asian Symposium on Poly-mers in Concrete, Istanbul, Turkeyrilem.net/gene/main.php?base= 600040#next_497

3-6NCPA 47th Annual Convention,

New Orleans, LAwww.precast.org/convention

2012

See the events calendar at www.concreteinternational.com for more listings

Meetings


Una solución de capa final autonivelante para suelos

Fulkerson, Brad, Concrete International, V. 34, No. 7, julio de 2012, págs. 46-49

Las losas sobre cubiertas de metal y encofrados de acero pueden acarrear desafíos específicos para el contratista de hormigón, especialmente cuando se deben alcanzar los límites de tolerancia de suelo plano y de humedad. Mediante el uso de un sistema de capa final a base de cemento, Sellen Construction, Seattle, WA, superó recientemente estos desafíos en la construcción del Swedish Hospital y el edificio de consultorios médicos en Issaquah, WA. Este artículo presenta la aplicación y las pruebas del sistema autonivelante Laticrete Supercap.

Preenfriamiento de hormigón en masa con nitrógeno líquido

Gajda, John y Sumodjo, Francisco, Concrete International, V. 34, No. 7, julio de 2012, págs. 50-52

Hace aproximadamente 30 años que se utilizó el nitrógeno líquido para enfriar hormigón por primera vez. Inicialmente, se utilizaba nitrógeno líquido para enfriar los ingredientes del hormigón antes de la mezcla, pero estas prácticas derivaron en problemas con las operaciones de dosificación y con la calidad del hormigón, por lo que eran ineficientes y caras. No obstante, en los últimos años el nitrógeno líquido ha ido ganando popularidad. Este artículo aborda el sistema automatizado CryoCrete™, desarrollado por Air Liquide Industrial U.S. LP, así como sus aplicaciones en diversos proyectos.

Entender los principios de los cortavientos

Suprenant, Bruce A., y Malisch, Ward R., Concrete International, V. 34, No. 7, julio de 2012, págs. 35-39

El secado de la superficie de hormigón fresco se inicia cuando la tasa de evaporación es superior a la tasa de exudación. Los cortavientos pueden proteger el hormigón frente al viento, la evaporación excesiva y la incidencia de agrietamiento por contracción plástica. Este artículo aborda la altura, porosidad, longitud, orientación y continuidad de los cortavientos como factores clave que afectan a la velocidad del viento en la zona protegida a favor del viento del cortavientos. También presenta ejemplos del uso adecuado de cortavientos en suelos de losas, losas elevadas y capa final de losas.

Hormigón óptimo para suelos de losas

Vruno, Daniel M. y Ramerth, Michael, Concrete International, V. 34, No. 7, julio 2012, págs. 40-45

Minnesota Concrete Council y Target Corporation se han asociado para adquirir conocimientos pertinentes sobre la optimización de las proporciones del hormigón para minimizar el arqueamiento, maximizar la capacidad de acabado y mejorar la sostenibilidad. Este artículo resume los resultados de estudios realizados en el laboratorio y sobre el terreno en mezclas de hormigón con diversas proporciones de agua/materiales cementosos, diversos contenidos totales de materiales cementos y varios niveles de sustitución de cemento con cenizas volantes y cemento de escoria.

Uso de agregados silíceos en hormigón: la experiencia de Texas, Parte 1

Wang, Hugh y Lukefahr, Elizabeth, Concrete International, V. 34, No. 7, julio de 2012, págs. 53-58

El Estado de Texas se ha visto ampliamente afectado por reacciones de álcalis agregados (AAR) en varias infraestructuras de transporte. A lo largo de los años y a través de programas de investigación, se ha detectado que las AAR en Texas se pueden atribuir principalmente a la reacción álcali-sílice (ASR) en el hormigón. Este artículo resume los resultados sobre mineralogía, morfología, reactividad y microestructuras de los agregados utilizados en los elementos de hormigón dañados. Un segundo artículo se centrará en las capacidades de control de la ASR y proporcionará análisis de las estructuras reales que presentan grietas en la superficie debidas a ASR.

Sinopsis en español

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Public

DiscussionDocument number Title

Open for discussion

Discussion closes

506.2 Specification for Shotcrete 6/1/2012 7/17/2012

Proposed Standards“Specification for Shotcrete”

The ACI Technical Activities Committee (TAC) approved processing the subject document through ACI’s Standardization Procedure in July 2011, as did the ACI Standards Board in May 2012.

Therefore, this draft document is open for public discussion from June 1, 2012, until July 17, 2012. The document appears on the ACI Web site, www.discussion.concrete.org.

Pertinent discussion will be available on ACI’s Web site and announced in a future issue of Concrete International if received no later than July 17, 2012. Comments should be e-mailed to [email protected] or mailed to Shannon Banchero, Manager, Technical Documents, American Concrete Institute, 38800 Country Club Drive, Farmington Hills, MI 48331.

The following ACI draft standard is open for public discussion. It is being processed through ACI’s ANSI- approved standardization procedures and is not yet an official ACI standard. To see a summary of all ACI draft standards in process or recently completed within the past 3 months, please visit www.discussion.concrete.org.


Concrete

Q&A

Questions in this column were asked by users of ACI documents and have been answered by ACI staff or by a member or members of ACI technical committees. The answers do not represent the official position of an ACI committee. Only a published committee document represents the formal consensus of the committee and the Institute.

We invite comment on any of the questions and answers published in this column. Write to the Editor, Concrete International, 38800 Country Club Drive, Farmington Hills, MI 48331; contact us by fax at (248) 848-3701; or e-mail [email protected].

Q. A concrete supplier for one of my projects wants to provide lightweight aggregate concrete with 6% air content to meet the specified unit weight. I typically

don’t allow air entrainment in floor slab mixtures to help minimize the risk of blistering from early finishing. What requirements or guidance on this topic is included in ACI committee documents or other resources?

A. This has been a controversial issue in recent years. While lightweight concrete is a useful material for meeting fire-resistance ratings, an air

content of 6% is probably not necessary to meet the required equilibrium density, which is often misunderstood in relation to the fresh unit weight measured at placement. In any case, concrete with a target air content of 6% should not be finished by hard troweling.

ACI documents deliver a somewhat mixed message on air entrainment, with conflicts generally due to differing requirements for protecting concrete from freezing damage and providing a flat surface finish. For example, both Section 4.4.1 of the ACI 318-111 Code and Section 4.2.2.4 of the ACI 301-102 specification require concrete to be air-entrained under certain exposure conditions. However, the Optional Requirements Checklist for Section 4.2.2.4 of ACI 301-10 informs the specifier that “air entrainment should not be used in flatwork to receive a hard steel-troweled finish.” Section 7 of ACI 301-10 specifically requires air entrainment for lightweight concrete exposed to weather but does not require air entrainment for all lightweight concrete and does not dictate the type of finishes that can be applied to exterior versus interior lightweight concrete. Section 11 of ACI 301-10, however, states that: “Concrete for slabs to receive a hard trowel finish shall not contain an air-entraining admixture or have a total air content greater than 3%.”

The concern is not hard-troweling lightweight concrete but hard-troweling air-entrained concrete. Entrained air slows the bleeding rate of concrete slabs and increases the risk of trapping bleedwater and coalesced air beneath a densified surface. In most cases, only one of the two

Finishing lightweight Air-Entrained Concrete

requirements (air entrainment or troweled finish) applies. Exterior concrete exposed to freezing and thawing, for example, is normally given a broom textured finish for slip/skid resistance, and hard-troweled finishes are typically limited to interior concrete floors that will not be subjected to large temperature fluctuations. Designers may be concerned about freezing damage to slabs in cold storage buildings, ice rinks, or buildings constructed during the winter, but the risk associated with blistering and delaminations due to hard troweling air-entrained concrete is greater than the risk associated with scaling of a slab subjected to only a few cycles of freezing and thawing. As long as new concrete has achieved the required strength and is given sufficient drying time prior to the first freeze, a low number of freezing-and-thawing cycles does not typically become problematic and air entrainment is not normally necessary.

But air entrainment is more common in lightweight concrete—it’s often needed to meet a fire-resistance rating, for example. And many specifications now require high flatness numbers, which are typically achieved using pans and troweling. Detailed recommendations on air entrainment for lightweight concrete are provided within some ACI reports and guidelines.

ACI 211.2-98,3 Section 2.4.1, for example, states: “When severe exposure is not anticipated, its [air entrainment’s] use may be waived, but the beneficial effects of air entrainment on concrete workability and cohesiveness are desirable and can be achieved at air contents of not less than 4.0%.” It also


states that entrained air lowers concrete density, and Section 2.4.3 indicates that air contents between 4 and 6% result in only a small reduction in concrete strength for concrete mixtures with a slump of 5 in. (125 mm) or less. This recommendation agrees with the statement in ACI 213R-03,4 Section 3.2.1.5: “Because entrained air reduces the mixing water requirement while maintaining the same slump, as well as reducing bleeding and segregation, it is normal practice to use air entrainment in lightweight concrete regardless of its exposure to freezing and thawing.”

Recommended ranges of total air content for lightweight concrete are 4.5 to 7.5% for a maximum aggregate size of 3/4 in. (19 mm) and 6 to 9% for a maximum aggregate size of 3/8 in. (9.5 mm). ACI 213R-03 further recommends using magnesium or aluminum screeds and floats before troweling and includes a section on good practices for achieving a satisfactory finish, such as performing all finishing operations after free surface bleeding water has disappeared. However, neither of these documents specifically recommends nor provides any guidance on troweling air-entrained light-weight concrete or limiting the air content when troweling is required.

Guidance on finishing concrete floors and slabs is given in ACI 302.1R-04.5 Section 6.2.7 states: “An air-entraining agent should not be specified or used for concrete to be given a smooth, dense, hard-troweled finish because blistering or delamination may occur. These troublesome finishing problems can develop any time the total air content is in excess of 3%.” This section doesn’t differentiate between normalweight and lightweight slabs. However, Section 8.3.11 further states: “Air-entrained concrete should never be used in any normalweight concrete floor slab that is to receive a hard-troweled finish.” Section 8.11 specifically discusses finishing lightweight concrete and states that “the finishing procedures differ somewhat from those used for a normalweight concrete. In lightweight concrete, the density of the coarse aggregate is generally less than that of the sand and cement. Working the concrete has a tendency to bring coarse aggregate rather than mortar to the surface. This should be taken into account in the finishing operations.” The guide then provides recommendations to control this tendency. One of the recommendations states: “Some lightweight aggregates can require further control of segregation, bleeding, or both. For this purpose, use no less than 4% entrained air in accordance with ACI 211.2.” Other recommendations for successful finishing of lightweight concrete include: • Avoid overworking or overvibrating the concrete, since

excess darbying or bull floating may cause finishing problems by driving down the mortar and bringing coarse aggregate into the surface;

• Use a magnesium darby or bullfloat instead of wood, because metal slides over coarse aggregate particles and embeds them instead of tearing or dislodging them;

• Float and trowel while concrete is still in a plastic state, after bleeding is complete. (Premature sealing of the concrete can result in blisters and delamination due to trapping of bleed water under the surface.); and

• Remove excess water from the surface with as little disturbance as possible. (Dragging a loop of heavy rubber garden hose over the surface is a simple and reliable method.)These recommendations do not suggest air-entrained

lightweight concrete can be hard troweled without risk. The higher the air content the greater the risk. The current ACI 302.1R document (issued in 2004) states that “...unlike its effect on normalweight concrete, the use of an air-en-training admixture in lightweight concrete that is to be hard-troweled does not lead to blistering.” However, this statement has been found to be incorrect in field studies of delaminations of trowel-finished lightweight air-entrained concrete slabs6 and was removed by vote of the committee in 2008. So, it will not appear in the next published ACI 302.1R guide.

Finishing operations using ride-on finishing machines initially equipped with pans and then equipped with combination floating and troweling blades produced the highest percentages of delaminated area on air-entrained lightweight slabs while non-air-entrained normalweight and lightweight slabs did not delaminate under any of the finishing procedures studied. Opinions provided in Reference 7 also indicate that proper timing of the application of walk-behind finishing machines with float pads, rather than pan floats, will decrease the risk of delaminations. However, while these recommendations seem simple, maintaining consistent timing of finishing operations is not possible without consistent air contents and setting behavior. These are difficult to achieve on large placements, where materials and ambient conditions usually vary. Additional factors are outlined in Reference 8, which recommends keeping the entrained air content of light-weight concrete at 3% and no more than 4%.

Although these limits are a good recommendation, consistently maintaining low percentages of entrained air can be challenging, particularly given the ±1.5% tolerance allowed by ASTM C94.9 For this reason, when troweling is required, it’s safest not to use an air-entraining admixture and limit the total air content to 3% maximum.

ACI Committee 302, Construction of Concrete Floors, is currently updating ACI 302.1R to incorporate newer field experience and guidance to finishing lightweight concrete. If air entrainment is required, careful timing of the start of

Concrete Q&A


floating operations, using only walk-behind finishing machines, equipping the finishing machines with float blades rather than float pans, and avoiding burnishing the finish with repeated troweling passes will minimize the probability of delaminations. However, because consistent timing of finishing operations is not always possible, the risk of blisters and delaminations can be further reduced by finishing air-entrained concrete only by bullfloating and using a thin topping or underlayment material to achieve the required surface flatness. In all cases, it’s advisable to have a preconstruction meeting with all members of the design and construction team prior to placing concrete slabs to discuss the factors involved and potential issues that may arise.

References1. ACI Committee 318, “Building Code Requirements for Structural

Concrete (ACI 318-11) and Commentary,” American Concrete Institute, Farmington Hills, MI, 2011, 503 pp.

2. ACI Committee 301, “Specification for Structural Concrete (ACI 301-10),” American Concrete Institute, Farmington Hills, MI, 2010, 77 pp.

3. ACI Committee 211, “Standard Practice for Selecting Proportions

Concrete Q&A

for Structural Lightweight Concrete (ACI 211.2-98) (Reapproved 2004),” American Concrete Institute, Farmington Hills, MI, 2004, 20 pp.

4. ACI Committee 213, “Guide for Structural Lightweight-Aggregate Concrete (ACI 213R-03),” American Concrete Institute, Farmington Hills, MI, 2003, 38 pp.

5. ACI Committee 302, “Guide for Concrete Floor and Slab Construction (ACI 302.1R-04),” American Concrete Institute, Farmington Hills, MI, 2005, 76 pp.

6. Ahal, D.C.; McCall, C.; and Suprenant, B.A., “Delamination of Trowel-Finished Lightweight Concrete Slabs,” Concrete International, V. 29, No. 6, June 2007, pp. 39-44.

7. Nasvik, J., “Finishing Lightweight Air-Entrained Concrete,” Concrete Construction, V. 50, No. 1, Jan. 2005, pp. 49-50, (www.concreteconstruction.net/concrete/finishing-lightweight-air- entrained-concrete.aspx).

8. Szabo, B., “Teamwork for Success,” Concrete Construction Annual Floors Issue 2008, (www.concreteconstruction.net/concrete-construction/teamwork-for-success.aspx).

9. ASTM C94/C94M-12, “Standard Specification for Ready-Mixed Concrete,” ASTM International, West Conshohocken, PA, 2012, 12 pp.

Thanks to Scott M. Tarr of North S.Tarr Concrete Consulting, PC, Dover, NH, for providing the answer to this question.

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