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TRANSCRIPT
Internal Curing of Concrete Pavements: State-of-the-Practice
Thursday, May 24, 20182:00-3:30 PM ET
TRANSPORTATION RESEARCH BOARD
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Credit earned on completion of this program will be reported to RCEP. A
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and attended the entire session. As such, it does not include content that
may be deemed or construed to be an approval or endorsement by RCEP.
Purpose
Provide an overview of the primary concepts of internal curing for concrete pavements.
Learning Objectives
At the end of this webinar, you will be able to:
• Describe the fundamentals of internally cured concrete pavements and their applications
• List the materials used for internally cured pavement applications
• Describe the process of construction for internally cured pavements
• Apply lessons learned from NYSDOT’s experience with internal curing
Internal Curing of Concrete Pavements
Transportation Research Board Webinar2:00 PM – 3:30 PM
Thursday, May 24, 2018
Sam Tyson, P.E.Concrete Pavement Engineer
FHWA Office of Preconstruction, Construction, and Pavements
Internal Curing of Concrete Pavements
TRB Committee/Webinar Sponsors –• AFD50 – Design and Rehabilitation of
Concrete Pavements• AFH50 – Concrete Pavement Construction
and Rehabilitation
Background: FHWA Publications• Internal Curing of Concrete Pavements
FHWA-HIF-16-006, August 2017https://www.fhwa.dot.gov/pavement/concrete/pubs/hif16006.pdf
…..and references cited in that document.
Internal Curing of Concrete Pavements
Jason Weiss, Oregon State University
• Introduction/Background• Mixture Design/Materials
• Quality Control• Construction
• Potential Benefits• Pavement Applications
Don Streeter, New York State DOT
• Bridge Deck Projects• Mixtures and Material
Handling• Construction QC/QA
• Performance Engineering Mixture (PEM) Specification
Internal Curing of Concrete Pavements
Samuel S. Tyson, P.E.Concrete Pavement Engineer
Office of Preconstruction, Construction, and Pavements
Federal Highway Administration1200 New Jersey Avenue, S.E. – E73-440
Washington, DC 20590
E-mail: [email protected]: 202-366-1326
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 1 of 37
Associated Technical Brief
• This presentation was developed to accompany FHWA Tech Brief HIF-16-006
• It will discussconcepts of ICfor concretepavements including:mixture design,construction, and quality control
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 2 of 37
Outline for Today’s Talk
• We want to discuss what internal curing is and where Internal Curing may have applications
• Mixture Design • Quality Control• Emerging Potential Benefits
– Reduce Joint Damage– Reduce ASR Damage (dilution/accomodation)– Reduced Built in Stress and Curing Times
• Pavement Applications ASR = Alkali Silica Reaction
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 3 of 37
What is Internal Curing?
• Internal curing water is simply water curing where the water is provided from inside the concrete
• In the US this is typically done currently by placing water inside the porous LWA
• This can also be done using superabsorbent polymers (SAP), absorptive fibers, or recycled concrete
• However currently these technologiesare not as readily available for usein pavements as is fine LWA LWA = Lightweight Aggregate
SAP = Superabsorbent Polymer
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 4 of 37
External and Internal Curing
Cast
ro e
t al.
2009
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 5 of 37
Where Has Internal Curing Been UsedWater Tanks - Bates et al. 2012Bridge Decks - DiBella et al. 2011
Pavements - Friggle et al. 2011 Patches - Barrett et al. 2014
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 6 of 37
Outline for Today’s Talk
• We want to discuss where Internal Curing may have applications
• Mixture Design • Quality Control• Emerging Potential Benefits
– Potential to Reduce Joint Damage– Potential to Reduce ASR Damage (dilution/accom.)– Reduced Built in Stress and Curing Times
• Pavement Applications
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 7 of 37
How Is IC Concrete Made
• Except for LWA, IC concrete mixture design generally is identical to that of conventional concrete with similar air content, water content, and coarse aggregate content.
• Currently, IC in North America is typically achieved by replacing a portion of the conventional fine aggregate (i.e., sand) with a pre-wetted lightweight fine aggregate.
IC = Internal Curing
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 8 of 37
Outline for Today’s Talk
• We want to discuss where Internal Curing may have applications for
• Mixture Design • Quality Control• Emerging Potential Benefits
– Reduce Joint Damage– Reduce ASR Damage (dilution/accomodation)– Reduced Built in Stress and Curing Times
• Pavement Applications
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 9 of 37
Mixture Design for Internal Curing
• similarities and differences between the design of a conventional 6-bag mixture (water-to-cement ratio of 0.36 and 6 percent air) and an IC mixture
• assumes 15% absorption of the FLWA
• 7 lb of IC water for every 100 lb of cementititiousmaterials.
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 10 of 37
Simple Mixture Proportioning
• Convert an existing paving mixture or a bridge deck mixture to an IC Mixture
LWA Absorption: 15.0%LWA Desorption: 85.0%
LWA Specific Gravity 1.750Cement Factor 704
Chemical Shrinkage: 0.065Degree of Hydration 1
SSD LWA Replacement 413SSD Sand Replaced 619
Internal Curing Properties
Materials Weight SG (SSD) Volume, ft3Cement 564 3.15 2.869GGBFS 115 2.99 0.616Fly Ash 0 2.64 0.000
Silica Fume 25 2.2 0.182Sand 591 2.623 3.613
Lightweight Aggregate 413 1.750 3.780Coarse Aggregate 1 1700 2.763 9.860Coarse Aggregate 2 0 2.763 0.000
Water 258 1 4.135Air 0 0 1.755
Σ 3666 - 26.810
IC Mixture Design
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 11 of 37
Outline for Today’s Talk
• We want to discuss where Internal Curing may have applications for
• Mixture Design • Quality Control• Emerging Benefits
– Potential to Reduce Joint Damage– Potential to Reduce ASR Damage (dilution/accom.)– Reduced Built in Stress and Curing Times
• Pavement Applications
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 12 of 37
Measuring Aggregate Properties
• Aggregate Moisture• Surface Moisture• Aggregate Absorp.• Specific Gravity
(Relative Density)• Desorption
• Spreadsheet andStep by Step Process(Miller et al 2014)
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 13 of 37
Outline for Today’s Talk
• We want to discuss where Internal Curing may have applications for
• Mixture Design • Quality Control• Emerging Potential Benefits
– Reduce Joint Damage– Reduce ASR Damage (dilution/accomodation)– Reduced Built in Stress and Curing Times
• Pavement Applications
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 14 of 37
Joint Damage and the Role of IC• Concrete pavement joints damaged by salt
3Ca(OH)2 + CaCl2 + 12H2O CaCl2·3Ca(OH)2·12H2OCalcium Oxychloride
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 15 of 37
IC and Calcium Hydroxide (CaOH2; CH)
• Ca(OH)2 forms in solution and deposits in/on aggregate• Ca(OH)2 deposits on aggregate surfaces (few to 20 µm)
as stage III begins (before set)• Ca(OH)2 will react with deicing salt
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 16 of 37
Reaction of SCM and the Role of IC
• IC provides additional water that can help to increase the cement that hydrates as well as the SCM that hydrates
• As such, IC will reduce (Ca(OH)2)and reduce jointdamage
0.25 0.30 0.35 0.40 0.45 0.50w/c
Internal CuringSealed
0.4
0.5
0.6
0.7
Deg
ree
of H
ydra
tion
at 7
2 h
(Hea
t / M
axim
um th
eore
tical
hea
t)
Castro et al. 2010
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 17 of 37
Outline for Today’s Talk
• We want to discuss where Internal Curing may have applications for
• Mixture Design • Quality Control• Emerging Potential Benefits
– Reduce Joint Damage– Reduce ASR Damage (dilution/accomodation)– Reduced Built in Stress and Curing Times
• Pavement Applications
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 18 of 37
Alkali Silica Reaction (ASR) and IC• Internal Curing Benefits –
– decreases porosity through hydration,– accommodation space allows gel without pressure, – dilution (replaces reactive aggregates)
• Internal Curing Disadvantages –– Higher RH/moisture
which would enable more ASR reaction to occur
RH = Relative Humidity
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 19 of 37
Alkali Silica Reaction (ASR) and IC• Reactive (R) – Most reactive and expansive• Non Reactive Aggregate Replacement at 15 & 28% (m) –
Reduces expansion due to dilution• Internal Curing – LWA Replacement at 15 & 28% % (N)) –
more effective even than non reactive aggregateLWA providesspace for expansive gel to form
• 15% replacementis CS volume Sh
in e
t al.
2010
CS = Chemical Shrinkage
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 20 of 37
Outline for Today’s Talk
• We want to discuss where Internal Curing may have applications for
• Mixture Design • Quality Control• Emerging Potential Benefits
– Reduce Joint Damage– Reduce ASR Damage (dilution/accomodation)– Reduced Built in Stress and Curing Times
• Pavement Applications
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 21 of 37
Benefits of IC - Thermal• IC makes concrete less susceptible to thermal
cracking, as “built-in” stress is reduced
Schlitter et al. 2010
Plain Concrete IC Concrete
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 22 of 37
Patching and Full Depth Panel Repair
• Field trials performed in Indiana in 2014 used IC with expanded slag aggregate in high early strength, full-depth concrete pavement patches
• Application of IC in the high early-strength patches provided a concrete with two distinct benefits when compared with conventional concrete: 1) reduced built-in stress and cracking caused by
the restraint of shrinkage, and 2) increased water curing (from inside the concrete)
after the patches are covered with curing compound and opened to traffic. 22
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 23 of 37
Patching and Full Depth Panel Repair
23
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 24 of 37
Outline for Today’s Talk
• We want to discuss where Internal Curing may have applications for
• Mixture Design • Quality Control• Emerging Potential Benefits
– Reduce Joint Damage– Reduce ASR Damage (dilution/accomodation)– Reduced Built in Stress and Curing Times
• Pavement Applications
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 25 of 37
CRCP Pavements
• Potential reduction in shrinkage, modulus and curling• May result in thinner sections or increased mechanical
performance and fatigue capacity • Initial crack spacing was approximately 3x longer than
those developed in conventional sections • Longer term monitoring has shown that this difference
in crack spacing decreases over time until the spacing is on the order of 20 to 30 percent longer than that in conventional concrete.
• Cracks in internally cured concrete remain tighter than those in conventional concrete
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 26 of 37
JPCP Pavements
• IC may improve durability by reducing moisture loss and improving hydration, from the extended moisture supply provided.
• IC reduces early age shrinkage and associated plastic shrinkage cracking
• Another potential benefit to jointed pavements is a reduction in upward slab curling resulting from internal slab moisture gradients and stresses locked in at the time of set resulting from temperature gradients during curing.
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 27 of 37
Applications of IC in Pavements 1
• A number of IC pavement have been placed, primarily in the Dallas-Fort Worth area using a relatively small substitution of intermediate aggregate sizes with lightweight aggregate.
• A residential subdivision in south Fort Worth, Windsor Park, constructed in 2006-2007. A survey after 8 years in service identified no significant longitudinal or transverse cracking, plastic shrinking cracking, spalling, or other defects. In general, the pavement was in excellent condition.
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 28 of 37
Applications of IC in Pavements 2
• 1,400-foot section of CRCP of State Highway 121 near Dallas in 2006
• Initially the cracks in the IC had a larger spacing
• After several years, the crack spacing wassimilar to that of the conventional sections; however, the cracks remained much tighter
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 29 of 37
Applications of IC in Pavements 3
• A 360-acre Union Pacific intermodal terminal located 12 miles from downtown Dallaswithin the city limits of Hutchins and Wilmer
• Minor joint spalls and limited cracking have been observed. Performance has been similar to the conventional sections, with both in excellent condition.
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 30 of 37
Applications of IC in Pavements 4
• A residential subdivision in north Fort Worth, Alexandria Meadows North, constructed in 2006-2007.
• Project contained streets both with and without internally cured concrete.
• A field survey revealed both the internally cured concrete and conventional pavement sections were in excellent condition, with very limited cracking.
• No slab curl was identified.
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 31 of 37
Summary - 1 • ICC has been successfully used in full-scale bridge
decks and concrete pavement patching projects. • ICC has similar workability, strength and mechanical
property development, reduced stress development and cracking, and similar or improved durability when compared with conventional concrete.
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 32 of 37
Summary - 2
• Aspects of proportioning and quality control – Excel worksheets for modifying a concrete mixture and for
quantifying the properties of the aggregate– Centrifuge test has substantial benefits in obtaining
surface dry conditions– Prewetting may need to be modified for IC pavements
due to the volume of material used
• Emerging Benefits for IC in pavement– Potential to reduce joint damage caused by salt– Potential to reduce ASR damage (dilution/accommodation)– Reduced curing times
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 33 of 37
Summary - 3
• Field trials examining the use of ICC in continuously reinforced concrete pavement, white topping, and jointed plain concrete pavements.
• Specific improvements hypothesized include:– reduced shrinkage, fewer and tighter cracks, – improved fatigue resistance, and – reduced slab curling/warping
• Pavement ME Design suggests that the performance of ICC pavements should be superior to conventional concrete pavements, resulting in improved life cycle
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 34 of 37
Additional Resources http://cce.oregonstate.edu/internalcuring
Internal Curing for Pavements Prepared by Jason Weiss, Dennis Morian and Shree Rao Slide 35 of 37
Acknowledgements and Disclaimer
• These slides were developed as a part of a series for the ARA by Jason Weiss and Dennis Morian.
• These materials are provided as general information and do not constitute legal or other professional advise.
• Any use of this information in the design or selection of materials for practice should be approved by the project owner and engineering-of-record.
35
1
Internal Curing ConcreteNew York Experience
Don Streeter - NYS DOT
Group Director, Accelerated Delivery and Innovative Deployment -
Structural Materials and Research
NYSDOT - Materials Bureau
2
Concrete Problems American’s spend 4.2 billion hours a year
stuck in traffic Bridges (>25%) are structurally deficient or
functionally obsolete Highways (>33%) are in poor
or mediocre condition ASCE 2017 report D+
3
Internal Curing (IC) Consideration
IC Portland Cement Concrete (PCC) data shown to have: good flexure slightly increased strength lower permeability / increased resistivity
Consideration for use in Pavements Non-wet cured PCC
4
IC Consideration Bridge deck considerations Scaling Freeze / Thaw (F/T) Cracking / Shrinkage
Pavement considerations Cracking / Shrinkage Flexural strength
5
Factors that contribute to deck cracking:* Span length / width / geometry* Continuous spans vs. simple span* Placement (staged vs. continuous)
6
7
Factors that contribute to pavement cracking:* Slab length / thickness / geometry* Subgrade / subbase conditions* Construction practices (timely curing)
8
Lab evaluation Comparing performance characteristics
for different ages of wet curing.
Evaluated control and IC mixtures Compressive strength Freeze / Thaw Scaling Shrinkage Surface Resistivity (SR)
9
Lab evaluation Evaluated 3, 7 and 14 day characteristics Samples cast and placed in fog room.
Specific curing regimes F/T and scaling moist cure for 3, 7, or 14
days then air dried for 24 hrs prior to placing in freezer
Resistivity moist cure for 3, 7 or 14 days then air dried until 28 days of age
10
Lab evaluation - results Results Shrinkage, F/T, and scaling - no significant
difference between control and IC mixture
Strength increased for IC mixtureControl IC
3 Day Comp, psi
3050 3430
7 Day Comp, psi
3950 4140
14 Day Comp, psi
4620 5220
11
Lab evaluation - results Results (con’t)
Surface Resistivity
NYSDOT Performance Engineered Mixture (PEM) SR spec proposed:
>24 kΩ-cm for decks
>16.5 kΩ-cm for pavements
Control IC3 Day Moist, 25 Day Dry SR, kΩ-
cm21.0 22.4
7 Day Moist, 21 Day Dry SR, kΩ-cm
22.8 24.9
14 Day Moist, 14 Day Dry SR, kΩ-cm
25.7 26.7
12
IC Specification - material Use of light-weight fine aggregates as a
replacement for sand
30% substitution by volume
Contractor designed mix, semi- prescriptive
Modified High-Performance Concrete (HPC) generally used.
13
IC structural mixture Cement – Type I 500 lbs Fly Ash 135 lbs Microsilica 40 lbs Fine Aggregate – Natural Sand 782 lbs Fine Aggregate – Expanded Shale 196 lbs Coarse Aggregate – 1 & 2 Blend 1720 lbs Water 262 lbs
14
Experimental plan - decks “Experimental Features” plan for FHWA 12 projects: up to 20 decks using IC PCC Compare to companion decks of similar size
/ design Measure cracking Focus on early age cracking (typically 60
days) Success – 30% reduction of cracking
15
IC production requirements Stockpile establishment Saturated Surface Dry
(SSD) condition – minimum 15%
absorbed moisture place under sprinkler
for minimum of 48 hours
allow stockpiles to drain for 12 to 15 hours prior to use
16
IC production requirements Batching Calculate absorbed and surface moisture (paper towel test)
Adjust batch weights by absorbed moisture only Absorbed water does not affect water-to-
cementitious (w/c) ratio Requires additional bin for plant production
Handling, delivery, and placement - Follow traditional practice
17
IC production / placement Batching observations Stockpile management Batching adjustments
Handling / placing Observe any difference in
handling, placing or finishing
Curing Use standard 14 day
duration
18
Case Studies / Evaluations NY Route 9W over Vineyard Avenue NY Route 96 over Owego Creek Interstate 81 at Whitney Point Court Street over Interstate 81 Bartell Road over Interstate 81 Interstate 86 over NY Route 415 Interstate 84 over Route 6 -overlay Interstate 290 Ramp B over Interstate 190
19
Case Studies / Evaluations Interstate 81 over East Hill Road NY Route 17 Exit 90 Ramp over East
BranchDelaware River
NY Route 38B over Crocker Creek NY Route 353 over Allegheny River -barrier Interstate 87 over Route 9 and Trout Brook Interstate 81 Connectors, Fort Drum -overlay
20
Court and Spencer Streets
21
Comparison – Court & Spencer
7 day 14 day 21 day 28 day
Compressive Compressive Compressive Compressive
Strength Strength Strength Strength
ConcreteType
(MPa) (MPa) (MPa) (MPa)
Spencer Street Bridge HPC 32.6 40.8 41.9 43.5Court Street Bridge HPC-IC 33.5 42.9 45.3 48.1
Percent Improvement 2.8% 5.1% 8.1% 10.6%
Cracking – none for either bridgeScaling and F/T performance very good
22
I-87 / Route 9 and Trout Brook
23
I-87 / Route 9 and Trout Brook
24
Comparison – I-87
7 day 14 day 28 day 28 day SR F/T
Comp Comp Comp Tensile
Strength Strength Strength Strength
ConcreteType
(psi) (psi) (psi) (psi) kΩ-cm % loss
HPC 4420 5215 5910 569 28 1.2
HPC-IC 4590 5790 6750 672 145 1.1
% Improvement 3.8% 11.0% 14.2%Cracking – no transverse cracking, significant map cracking SBBarriers – used HPC NB, HPC-IC SB, both show cracking
25
Deck cracking observations IC PCC and companion decks completed
Reduced cracking observed Not consistent results for all decks Geometry, number of spans, placement
procedures all impact performance
Conclusion of experiment: Require IC for all deck mixtures
26
Pavement Considerations Move to Performance Engineered Mixtures
Shrinkage requirements included Desire for early loading – flexure Well graded aggregate portion
IC will be one means of achieving performance characteristics
27
Conclusions Saturated light weight fines can improve
PCC properties IC material must have proper moisture
Addition of IC materials Requires added production efforts / expense Does not effect the finishability of concrete Provides better hydration – more efficient use
of cement and SCM resulting in improved performance characteristics
Curing durations can be reduced
Today’s Participants• Sam Tyson, U.S. Federal Highway
Administration, [email protected]• Jason Weiss, Oregon State University,
[email protected]• Don Streeter, New York State
Department of Transportation, [email protected]
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