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

rita.lederle@stthomas.edu

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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