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Blending of Higher Strength Aggregates with Recycled
Concrete and Marginal Aggregates to Improve Concrete
Properties
A Proposal for the National Road Research Alliance
August 9, 2019
PI: Rita Lederle, PhD, PE
Assistant Professor
University of St. Thomas – Civil Engineering
Mail OSS100
2115 Summit Ave
St Paul MN 55105
651-962-7745
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Abstract
Alternative aggregates are becoming increasingly needed as population centers begin to run out
of viable aggregate for concrete construction. Recycled concrete aggregate (RCA) and marginal
virgin aggregates have the potential for use in concrete, but often adversely affect concrete
properties such as strength and stiffness, which can lead to decreased pavement performance.
Blending of these aggregates with a stronger and stiffer aggregate such as taconite or granite
could mitigate concerns and allow for the use of RCA and marginal aggregates in paving
concrete without compromising properties or performance. Taconite, a byproduct of the iron ore
mining industry, shows promise as one such aggregate for use in blending; other strong and stiff
aggregates such as granite may also be options. Taconite and granite both have properties that
make them desirable for use as an aggregate in concrete, including hardness, strength, durability,
and a very high percentage of fractured faces.
The purpose of this study is to determine how the use of higher strength and stiffness coarse
aggregates such as taconite or granite blended with RCA and marginal aggregates affects the
properties of concrete for paving applications. Using taconite or granite in combination with
recycled and marginal aggregate in concrete will simultaneously reduce the demand for
increasingly scarce traditional aggregates and provide a means of using more cost effective
marginal and recycled aggregates. Additionally, in the case of taconite, this will provide a use for
a waste stream.
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Introduction and Background
Like many population centers, the Twin Cities Metropolitan Area of Minnesota is poised to run
out of viable aggregate for concrete construction in the near future (Southwick et al. 2000).
When local aggregates are scarce, contractors and ready mix concrete companies will have to
import aggregates from other locations, or resort to using lesser quality aggregates. Importing
aggregate is expensive in terms of both transportation costs and carbon emissions, while using
poor quality aggregate can negatively impact properties of the concrete.
Two plentifully available aggregate sources are marginal aggregates and recycled concrete
aggregates (RCA), though both have associated challenges. RCA is known to increase shrinkage
and may lower the compressive and flexural strength and elastic modulus of the concrete
(Ozbakkaloglu et al. 2018), which is associated with decreased pavement performance (Reza
2017). Though RCA can be used successfully in concrete pavements, these decreased properties
must be accounted for in design. Similarly, marginal aggregates can decrease stiffness as well as
compressive, split tensile, and flexural strengths, which is associated with poorer predicted
pavement performance (Bekoe and Tia 2014)
In contrast to the effects of RCA and marginal aggregates, using a higher strength or higher
stiffness aggregate such as granite can result in a concrete with higher compressive strength and
higher elastic modulus (Neville 2012). Another aggregate with the potential to increase the
strength and stiffness of the concrete is taconite, a byproduct of the iron mining industry in
northern Minnesota. Minnesota mines produce enough taconite every year to replace all of the
aggregate used in construction projects in the state twice over (Zanko et al. 2009). The existing
infrastructure used to ship iron ore across the United States could also be used ship taconite
because it is coming from the same source and has similar handling requirements (Oreskovich
2016).
Granite is generally considered to be a desirable aggregate because it has high strength and good
durability (Neville 2012). Additionally, because it is a manufactured aggregate, it generally has a
rougher surface texture, higher angularity, and fewer fines (Kosmatka and Wilson 2016).
Similarly, taconite has many properties that make it desirable for use as an aggregate in concrete,
including hardness, strength, durability, a very high percentage of fractured faces, and very little
material passing the #200 sieve.
The nomenclature surrounding taconite can be confusing because taconite can refer to the iron
rich material as mined, or the low iron content rock removed to access the iron rich material
(sometimes called overburden), or the rock remaining after iron ore has been extracted
(sometimes called tailings) (Zanko et al. 2012). For this proposal, one of the coarse aggregates
being investigated is coarse crushed taconite rock, which comes from the overburden. For clarity
and brevity, in this proposal, the term taconite will be used to refer to the material replacing the
coarse aggregate in the taconite concrete.
Since mining began in the early 1950’s, taconite has seen some use in road construction in
northern Minnesota, particularly as a base material and as an aggregate in asphalt pavements.
Taconite has also been used in overlays throughout the state and in specialty a pavement for the
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Brainer International Raceway (Oreskovich 2016). While taconite use in asphalt is fairly
common and well documented, there is only one instance of taconite being used in concrete
available in the literature. Taconite was used as the coarse aggregate in a test cell at the
Minnesota Road Research Facility (MnROAD) as a proof of concept (Izevbekhai and Rohne
2008) and it has been performing well (Rohne 2010). This study did find that the stiffness and
flexural strength of taconite concrete were higher than would be expected for concrete made with
traditional aggregates, which could lead to pavements with higher induced stresses when
subjected to loading (Zanko et al. 2009).
Currently, the University of St. Thomas is conducting research into the use of taconite as a
coarse and fine aggregate in concrete. The goal of this ongoing research project is to determine
how the use of taconite aggregate affects the mechanical properties of concrete. The proposed
study will be an extension of this ongoing research with the goal of using the beneficial
properties of high strength, high stiffness aggregates such as taconite and granite to offset the
negative effect of using other aggregates.
Objectives
The objective of this study will be to determine how the use of higher strength and stiffness
aggregates such as taconite and granite blended with RCA and marginal aggregates affects the
mechanical properties of concrete. The significance of this work is in its potential to allow RCA
and marginal aggregates to be used effectively in paving applications without major changes to
the concrete. Additionally, if it can be shown that an optimal blend of aggregates results in a
concrete with similar properties as concrete made with standard aggregate, then standard
pavement designs and details will require no modification.
Using taconite and granite blended with RCA and marginal aggregates in concrete could have a
significant impact on the economic viability and sustainability of concrete. As population centers
begin to experience scarcity of high-quality aggregates, alternative solutions will become
necessary. Importing high quality aggregates from distant sources will be increasing expensive
and unsustainable. However, RCA and marginal aggregates will still be available locally and
affordably. Blending high strength, high stiffness aggregates like granite with RCA and marginal
aggregates will keep the supply of granite available longer because less material is required.
Conversely, more taconite is always being produced so there is no imminent risk of a shortage.
The potential to ship taconite via existing rail lines and barge routes means that transporting
taconite to locations in Minnesota and elsewhere will be less carbon intensive than transporting
other aggregates, which rely on more carbon intensive truck hauling. Because Minnesota
produces more taconite than would be required to satisfy local construction demand, taconite
could also be exported to other areas of the country experiencing aggregate shortages.
Variables
The main variable that will be explored in this research is the amount of either taconite or granite
and the amount of either RCA or marginal aggregate in the blend. The properties of each
individual aggregate are also variables in this experiment. The variable of the blend ratios will be
controlled by testing blends at different levels of aggregate content, as discussed below and
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shown in Table 1. The variability between aggregates will be controlled through aggregate
source selection.
Hypothesis
The hypothesis of this research is that blending taconite and granite with RCA and marginal
aggregates will result in concrete with mechanical properties similar to that of standard concrete
made from quality virgin aggregates. This concrete could then be used for concrete pavements
without a change in design or construction procedure and would be expected to have a similar
level of pavement life.
Methodology
Data Collection and Analysis
To test the hypothesis, concrete with different blends of aggregates will be tested and compared
to various control groups. Aggregates tested will include a virgin aggregate, an RCA, a marginal
aggregate, granite, and taconite. All aggregates will be obtained from local aggregate suppliers.
The virgin aggregate, RCA, and granite will be aggregates typically used in the production of
ready-mix paving concrete. Because taconite and marginal aggregates are not often used in
concrete production, there is no standard aggregate available. However, the gradation and other
characteristics of these aggregates will be as similar as possible to that of aggregate commonly
used in concrete production.
All aggregates will be characterized via ASTM standards to determine the gradation (ASTM
C136), specific gravity and absorption (ASTM C127, C128), and moisture content (ASTM
C566). Concrete will be mixed in accordance with ASTM C192 and will use a standard mix
design commonly used for paving mixes. Basic plastic concrete testing, including air content
(ASTM C231), slump (ASTM C143), and temperature (ASTM C1064), will be performed.
Cylinder, prism, and beam specimens will also be cast and cured, per applicable ASTM
standards.
The compressive strength (ASTM C39) and flexural strength (ASTM C78) will be tested with
time to determine how blending affects both ultimate strength and the rate of strength gain. Other
mechanical properties to be tested are elastic modulus and Poisson’s ratio (ASTM C469).
Additionally, non-mechanical properties of coefficient of thermal expansion (AASHTO T336),
freeze thaw durability (ASTM C666), and shrinkage (ASTM C157) will be tested. These
properties were selected because they align with the needs of a pavement designer using
mechanistic-empirical pavement design (MEPDG) methods (NCHRP 2004). Freeze-thaw
durability was also included even though it is not a mechanistic-empirical pavement design input
because it is a necessity for pavements in northern regions.
3D Digital image correlation (DIC) will also be used to map the strain fields in the concrete
during the compressive strength test. DIC is a non-contact, full field optical imaging technique.
A speckle pattern applied to a surface of the concrete is photographed using high speed cameras
during loading. Software tracks the displacements recorded in the images to provide
measurements of displacements. A surface is fit across this field of displacement from which
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strains are then approximated. The software is capable of analyzing in-plane strains on planar or
three-dimensional (e.g. curved) surfaces. The method has previously been used on concrete by
several other researchers (ex. Corr et al. 2007) and Figure 1 shows a strain field that was
measured on a concrete cylinder in compression from previous research at the University of St.
Thomas. In the proposed work, DIC will be used to examine changes in the global field
(including mean values, standard deviations, etc.) due to the use of various aggregate blends.
Additionally, the strain field at specific regions can be measured during post processing to track
strains across specific linear paths. Strain fields measured just prior to fracture will also be
studied to help understand microstructural effects of using different aggregates.
Figure 1: Strain fields in concrete during compression testing
To accurately capture the effects of each type of aggregate on concrete properties, a large test
factorial and multiple control groups are necessary. The full factorial is shown in Table 1 and
includes mixes that look at various blending levels of taconite with RCA, taconite with marginal
aggregates, granite with RCA, granite with marginal aggregate, and control groups of virgin
aggregate with each taconite, granite, RCA, and marginal aggregate. Because of the large
number of mixes included, it will be possible to isolate the effects of each aggregate on mix
properties.
Once testing is complete, the results of each test will be compared for various blends. Plots can
be generated to show if/how each property investigated varies with the percent of taconite,
granite, RCA, or marginal aggregate. Because of the large number of control samples, it will be
possible to determine if the blending of the RCA and marginal aggregates with the granite and
taconite results in improved concrete properties versus using a single aggregate along as well as
if the blend has properties similar to that of a virgin aggregate. Additionally, because multiple
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blend levels are being investigated, it will be possible to determine if it is likely that there is an
optimal blend, though further testing will be required to that specific blend level.
Table 1: Testing Factorial
mix Virgin Granite Taconite RCA Marginal
V 100% - - - -
G - 100% - - -
T - 100% - -
R - - 100% -
M - - - 100%
VG25 75% 25% - - -
VG50 50% 50% - - -
VG75 25% 75% - - -
VT25 75% - 25% - -
VT50 50% - 50% - -
VT75 25% - 75% - -
VR25 75% - - 25% -
VR50 50% - - 50% -
VR75 25% - - 75% -
VM25 75% - - - 25%
VM50 50% - - - 50%
VM75 25% - - - 75%
GR25 - 75% - 25% -
GR50 - 50% - 50% -
GR75 - 25% - 75% -
GM25 - 75% - - 25%
GM50 - 50% - - 50%
GM75 - 25% - - 75%
TR25 - - 75% 25% -
TR50 - - 50% 50% -
TR75 - - 25% 75% -
TM25 - - 75% - 25%
TM50 - - 50% - 50%
TM75 - - 25% - 75%
Communication of Results
The results of this research will be disseminated through several venues. Anticipated products of
this research include an article for the Transportation Research Record journal and conference
presentations at the Transportation Research Board Annual Meeting (TRB) and the annual
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NRRA conference. Status updates and a final report will be provided to the NRRA and the
industry partner. All research results will be available in the public domain without restrictions.
Schedule
This project is anticipated to span approximately 1.5 years, with the bulk of the lab work
occurring in the summer. The full project schedule is shown in Table 2. Interim project updates
will be provided at time intervals as requested by NRRA and the final report will be provided
upon completion of the project.
Table 2: Project Schedule
Task Spring
semester Summer semester
Fall semester
Spring semester
Literature review
Material acquisition
Aggregate characterization
Mix design development
Concrete mixing and testing
Data analysis
Final report writing
Final report review
Budget
The research proposed in this grant will be funded through a combination of the grant award,
industry partnership with the Aggregate Ready Mix Association of Minnesota (ARM), and
leveraging University of St. Thomas resources. The full budget for this project is shown in
Table 3 and includes funding for materials and supplies, salaries, and conference travel
for disseminating research.
ARM will fund 22% of the project through the donation of materials, time, and expertise. ARM
has committed to donating materials valued at $1000, as well as staff time valued at $8100.
The equipment and supplies values in the budget include the purchase value of the aggregates as
well as cement and any required admixtures and supplies such as cylinder molds. The staff time
is based on the university standard rate for the principle investigator to oversee student workers.
The student worker stipends are based on a $12/hr rate for 10 hours per week in the academic
year and 30 hours per week in the summer.
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Table 3: Project Budget
Units Cost/unit Total Cost
Equipment and Supplies
Materials (ARM in-kind contribution) 1 $ 1,000.00 $ 1,000.00
Supplies 1 $ 500.00 $ 500.00
Staff Time
PI salary 1 $ 5,088.00 $ 5,088.00
Student worker stipend - summer 2 $ 4,500.00 $ 9,000.00
Student worker stipend - school year 2 $ 3,600.00 $ 7,200.00
ARM staff time 1 $ 8,100.00 $ 8,100.00
Sub Total $ 30,888.00
Overhead
Fringe Benefits 7.65% $ 1,077.73
Indirect Costs 41.4% $ 9,466.41
Grand Total $ 41,432.15
ARM Contribution (22%) $ 9,100.00
NRRA Contribution (88%) $ 32,332.15
While the budget for student workers may appear smaller than is typical, it should be noted that
all student workers at the University of St. Thomas are undergraduates and therefore do not
require the same level of support as the graduate students used at other institutions. The student
workers on this project will be performing tasks such as mixing concrete under the supervision
of the principle investigator. These tasks are well within the capabilities of properly trained
undergraduate students and are similar to tasks they perform in their construction materials class.
Additionally, this type of research experience can help introduce undergraduate students to the
field of concrete materials research and influence their decisions regarding future career paths
and graduate school.
The existing lab facilities at the university will be used for the majority of the testing and
additional internal funds are available to purchase some required equipment. To support this
research, the University of St. Thomas will also provide any assistance required from the lab
manager.
Partnerships
As discussed previously, ARM has agreed to support this project through the donation of
materials, and expertise. ARM will be available to answer questions regarding common industry
practices and provide valuable feedback from a user perspective throughout the study.
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References
AASHTO. "T336 Standard Method of Test for Coefficient of Thermal Expansion of Hydraulic
Cement Concrete." Amerian Association of State Highway and Transportation Officials,
Washington DC.
ASTM. (2018a). "C192/C192M Standard Practice for Making and Curing Concrete Test
Specimens in the Laboratory." ASTM International, West Conshohocken PA.
ASTM. (2018b). "C39: Standard Test Method for Compressive Strength of Cylindrical Concrete
Specimens." ASTM International, West Conshohocken PA.
ASTM. (2018c). "C78/C78M Standard Test Method for Flexural Strength of Concrete (Using
Simple Beam with Third-Point Loading)." ASTM International, West Conshohocken PA.
ASTM. (2017a). "C1064/C1064M Standard Test Method for Temperature of Freshly Mixed
Hydraulic-Cement Concrete." ASTM International, West Conshohocken PA.
ASTM. (2017b). "C157/C157M Standard Test Method for Length Change of Hardened
Hydraulic-Cement Mortar and Concrete." ASTM International, West Conshohocken PA.
ASTM. (2017c). "C231/C231M Standard Test Method for Air Content of Freshly Mixed
Concrete by the Pressure Method." ASTM International, West Conshohocken PA.
ASTM. (2015a). "C127 Standard Test Method for Relative Density (Specific Gravity) and
Absorption of Coarse Aggregate." ASTM International, West Conshohocken PA.
ASTM. (2015b). "C128 Standard Test Method for Relative Density (Specific Gravity) and
Absorption of Fine Aggregate." ASTM International, West Conshohocken PA.
ASTM. (2015c). "C143 Standard Test Method for Slump of Hydraulic-Cement Concrete."
ASTM International, Westh Conshohocken PA.
ASTM. (2015d). "C666/C666M Standard Test Method for Resistance of Concrete to Rapid
Freezing and Thawing." ASTM International, West Conshohocken PA.
ASTM. (2014a). "C136/C136M Standard Test Method for Sieve Analysis of Fine and Coarse
Aggregates." ASTM International, West Conshohocken PA.
ASTM. (2014b). "C469/C469M Standard Test Method for Static Modulus of Elasticity and
Poisson's Ratio of Concrete in Compression." ASTM International, West Conshohocken PA.
ASTM. (2013). "C566 Standard Test Method for Total Evaporable Moisture Content of
Aggregate by Drying." ASTM International, West Conshohocken PA.
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Bekoe, P. A., and Tia, M. (2014). "Concrete Containing Marginal Aggregates for Use in
Concrete Pavement." Journal of Civil Engineering and Architecture, 8(11), 1414-1423.
Corr, D., Accardi, M., Graham-Brady, L., and Shah, S. (2007). "Digital Image Correlation
Analysis of Interfacial Debonding Properties and Fracture Behavior in Concrete." Engineering
Fracture Mechanics, 74(1), 109-121.
Izevbekhai, B. I., and Rohne, R. (2008). "MnROAD Cell 54: Cell Constructed with Mesabi-
Select (Taconite Overburden) Aggregate; Construction and Early Performance." Minnesota
Department of Transportation, St. Paul MN.
Kosmatka, S. H., and Wilson, M. L. (2016). Design and Control of Concrete Mixtures. Portland
Cement Association, Skokie IL.
NCHRP. (2004). "Guide for Mechanistic-Empirical Design of New and Rehabilitated Pavement
Structures: Part 2 Design Inputs: Chapter 2 Materials Characterization." Transportation Research
Board, Washington DC.
Neville, A. M. (2012). Properties of Concrete. Pearson, Harlow UK.
Oreskovich, J. A. (2016). "A Brief History of the Use of Taconite Aggregate (Mesabi Hard
RockTM) in Minnesota (1950s – 2007)." Natural Resources Research Institute, Duluth MN.
Ozbakkaloglu, T., Gholampour, A., and Xie, T. (2018). "Mechanical and Durability Properties of
Recycled Aggregate Concrete: Effect of Recycled Aggregate Properties and Content." ASCE
Journal of Materials in Civil Engineering, 30(2), 4017275.
Reza, F. (2017). "Evaluation of recycled Aggregates Test Section Performance." Minnesota
Department of Transportation, St. Paul, MN.
Rohne, R. J. (2010). "Mesabi-Select Concrete Pavement Year 5 Performance Report." Minnesota
Department of Transportation, St. Paul MN.
Southwick, D. L., Jouseau, M., Meyer, G. N., Mossler, J. H., and Wahl, T. E. (2000).
"Information Circular 46. Aggregate Resources Inventory of the Seven-County Metropolitan
Area, Minnesota." Minnesota Geological Survey, St. Paul MN.
Zanko, L. M., Johnson, E., Marasteanu, M., Patelke, M. M., Linell, D., Moon, K. H.,
Oreskovich, J. A., Betts, R., Nadeau, L., Johanneck, L., Turos, M., and DeRocher, W. (2012).
"Performance of Tacnoite Aggregates in Thin Lift HMA." Federal Highway Administration,
Washington DC.
Zanko, L. M., Fosnacht, D. R., and Hopstock, D. M. (2009). "Construction Aggregate Potential
of Minnesota Taconite Industry Byproducts." Cold Regions Engineering 2009: Cold Regions
Impacts on Research , Design, and Construction, ASCE, Reston VA, 252-274.
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Appendix A: Qualifications of Investigator and Institution
Investigator
Dr. Lederle is an assistant professor at the University of St. Thomas, studying concrete
infrastructure with a particular emphasis on concrete materials. Her past research experience
includes investigating the use of recycled materials as aggregates and pozzolans in paving
concrete and examining the feasibility of using self-consolidating concrete in pre-cast bridge
girder construction. She has also developed design models for concrete pavements to account for
the effects of reversible shrinkage on transverse cracking prediction and to predict fatigue
damage associated with longitudinal cracking. Prior to joining the university, Dr. Lederle worked
for both the Minnesota and Wisconsin Departments of Transportation, which has provided her
with the ability to examine research projects through the lens of implementation in addition to
academically.
Previous Projects Investigating Concrete Materials
Reversible Shrinkage of Concrete Made with Various Aggregates including RCA
Studied the amount of reversible and irreversible shrinkage experienced by concrete
made of various aggregates including several different recycled concrete aggregates and
light weight aggregates. Investigated the effects of different curing regimes on reversible
shrinkage and the long held assumption that length change in concrete is proportional to
weight change.
Investigation of Hydrochars as a Supplementary Cementitious Material
Tested the cementitious and pozzolanic properties of waste materials processed with
hydropyrolization techniques developed by the Biotechnology Institute at the University
of Minnesota.
Self-Consolidating Concrete for Prestressed Bridge Girders
Oversaw an investigation of the use of self-consolidating concrete in bridge girder
fabrication. Advised the development of self-consolidating mix designs and a research
testing plan. This project examined the effect of various aggregate types and gradations
on overall mix properties and performance.
Previous Projects Investigating Pavement Design
Development of a Longitudinal Cracking Fatigue Damage Model for Jointed Plain
Concrete Pavements Using the Principals of Similarity
Developed a model that uses neural networks to predict stresses which cause longitudinal
cracking for pavement subjected to environmental and traffic loading. The neural
networks were trained in similar space with a factorial which was reduced in size using
the principles of similarity to increase efficiency without introducing error. A modified
version of Miner’s fatigue was used to accumulate damage caused by these loads.
Consideration was given to the fact that longitudinal cracks do not occur independently
of each other.
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Development of New Warping and Differential Drying Shrinkage Models for Jointed
Plain Concrete Pavements
Developed models to predict the amount of warping and differential drying shrinkage
experienced by a concrete slab due to ambient relative humidity. These models improve
upon existing models by assuming a non-linear shrinkage gradient but do not require any
additional inputs and are fully compatible with current mechanistic-empirical design
procedures.
Relevant Peer-Reviewed Publications
Torres, E., Seo, J., and R.E. Lederle. “Experimental and Statistical Investigation of Self-
Consolidating Concrete Mixture Constituents for Prestressed Bridge Girder Fabrication.”
ASCE Journal of Materials in Civil Engineering, Vol. 29, No 9, 2017.
Torres, E., Seo, J., and R.E. Lederle. “A Framework to Examine Experimental Material
Properties of Self-Consolidating Concrete for Prestressed Bridge Girder Fabrication.”
Proceedings of the 8th International RILEM Symposium on Self-Compacting
Concrete/6th North American Conference on Design and Use of Self-Consolidating
Concrete, Washington DC, May 2016.
Lederle, R.E., and J.E. Hiller. “Reversible Shrinkage of Concrete Made with RCA and
Other Aggregate Types.” ACI Materials Journal, Vol. 110, No 4, p 423-432, 2013.
Lederle, R.E. and J.E. Hiller. “New Warping and Differential Drying Shrinkage Models
for Jointed Plain Concrete Pavements Derived with a Nonlinear Shrinkage Distribution”
Transportation Research Record 2305, p 3-13, 2012.
Hiller, J.E., Lederle, R.E., and Deshpande, Y.S. “Characterization of Recycled Concrete
Aggregates for Reuse in Rigid Pavements.” Proceedings of the 2011 Australian Society
for Concrete Pavements Conference, West Ryde, New South Wales, Australia, August
2011.
Institution
The University of St Thomas School of Engineering has laboratory space occupying
approximately 10,000 square feet, and is partitioned into several specialized areas. The space is
designed to meet the high-tech requirements of the profession and to be flexible and adaptable to
changing industry needs. The laboratories are equipped with tools including production
machinery, research instrumentation, test equipment, educational demonstrations and models,
and simulation and design software. The laboratories are managed by four lab managers (one for
each of the civil, electrical, and mechanical labs, and the woodshop) who are responsible for
maintaining the OSHA compliant labs and ensuring a safe environment for all involved. These
lab managers are also able to provide assistance to student workers on research projects.
The civil engineering materials lab is equipped for standard testing of concrete and soils per
ASTM standards. Concrete mixing equipment includes a 3-cubic foot rotary mixer, two bench
top 5-qt mortar mixers, and a custom designed water recycling system for responsibly containing
and disposing of washout water. Standard molds are available for casting 3, 4 and 6 inch
diameter cylinders, flexural beams, and mortar cubes. Curing is facilities include heated cure
tanks and a 155-cubic foot Darwin cure chamber. A Fourney 500,000 lb. High Stiffness Frame
compression tester with digital control and readout has all accessories required to conduct
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compression, split tensile, modulus of rupture (via four point bending), modulus of elasticity, and
Poisson’s ratio testing on standard sized cylinders and beams. This machine can also conduct
masonry testing on mortar cubes, bricks, concrete masonry units, and masonry prisms. For
aggregate testing, two sieve shakers and a sieve screen are available with all required
sieve/screen sizes for gradation testing, and equipment required for coarse and fine aggregate
specific gravity and absorption capacity testing. Soils testing equipment includes a pneumatic
direct shear machine with digital readout, two odeometers for consolidation testing, and two 10-
kip load frames with accessories required to conduct unconfined compression and California
bearing ration, as well as triaxial testing when used with control panels. Additional soils
equipment includes sieve sizes required to conduct soils gradations, equipment for hydrometer
testing, two bench top lab ovens (550°F maximum), four stations to conduct constant and falling
head tests with rigid wall permeameters, and sundry sample preparation tools.
The combined civil and mechanical materials testing lab includes an MTS Criterion Series C43
universal testing machine. This machine has a variety of grips for testing in tension,
compression, and flexure. Extensometers and associated software allow for measurement of
deformation during testing. A digital image correlation system is also available to record real-
time strain field measurements. Additionally, a higher capacity MTS Criterion Series C45-605
machine is on order with expected delivery in fall 2019. This will allow for a wider range of
materials testing, particularly civil engineering materials. Rounding out this lab are an MTS
Exceed 22 Pendulum Impact Tester, a Rockwell hardness tester, and a guided bend tester.
A machine shop of approximately 600 square feet exists with manually operated milling
machines, manually operated lathes, and a horizontal band saw, in addition to three CNC
machines with the capability to accept processed CAD files from which parts can be made. There
are also “light manufacturing” facilities, including sanders, arc welding, sheet metal equipment,
numerous hand tools, and adequate bench space.
The School of Engineering also has a woodshop with a table saw, band saw, 10inch sliding
compound miter saw, drill press, panel saw, router station with a 2¼ HP router, oscillating
spindle sander, 12inch disc sander, scroll saw, 13” helical power planer, downdraft table,
portable spray booth and numerous hand tools suitable for working with wood, and even metal or
plastic (special blades/bits may be required). Ventilation is provided in the wood shop by an air
filtration system with 5HP dust collector. Additional tools for a variety of applications
(electrical, plumbing, construction, etc.) are available from the tool lending library located
adjacent to the labs.
The University of St. Thomas library is well equipped to assist with research by providing online
access to databases, journals, and periodicals. For testing, a complete digital subscription to all
ASTM standards is provided. Interlibrary loan services provide access to material not housed
physically or digitally in the library. A dedicated librarian is available to assist engineering
students and faculty with research