2022
ARDOT TRC 2203: Low Shrinkage Concrete Mixtures for Arkansas
While most bridge decks in Arkansas perform adequately over their design life, early-age shrinkage cracking is a recurring issue in some bridges that can lead to compromised durability. Shrinkage cracks may lead to serious deterioration such as rebar corrosion and freezing and thawing damage. This shrinkage can be reduced by changing the mixture design or materials, improving construction procedures, and changing structural design parameters.
The objectives of this study are two-fold:
1) Determine the effect of various Arkansas coarse aggregates on the drying shrinkage in standard bridge deck mixtures, and
2) develop a low-shrinkage concrete specification modeled on other state specifications tailored to Arkansas materials.
A review of approved quarries on the ARDOT QPL reveals a minimum of 7 major coarse aggregate types approved for use in ARDOT concrete. Therefore, though bridge decks may contain the same cementitious content and utilize similar construction practices, drying shrinkage may be much more of a concern with specific Arkansas aggregates. Determining the impact of aggregate type on drying shrinkage would help reduce bridge deck cracking and improve long-term durability.
Considering the development of low-shrinkage specifications, the approach will be two-fold. First, materials recommendation will be developed (a maximum cement content, suggested aggregate/admixture interventions). Secondly, a performance test will be recommended (maximum drying shrinkage by ASTM 157 (ASTM Standard C157 2017) or AASHTO T160) to ensure the quality of the low-shrinkage concrete mixture. The suggested mixtures in this project may include lightweight aggregate (to reduce concrete modulus), shrinkage reducing admixture, and/or fly ash to cause the lowest amount of shrinkage. The resulting mixture design specification can be used for bridge deck concrete to ensure long-lasting bridges.
Development of an Innovative Rapidly Constructible Bridge
This project is a preliminary concept study to develop creative solutions for the rapid deployment of temporary bridge structures, considering bridge super-structure and deck deployment. In this project, compact tensegrity super-structures are considered along with origami-inspired cement-impregnated decking or more traditional concrete decks made with lightweight concrete. It is anticipated that the project will result in a rapidly deployable bridge configuration (from storage to function within a few hours) that is capable of transporting military vehicle loads over short-to-medium spans. This project will develop advanced pavement technologies for rapid deployment, and lay the groundwork for future prototyping and strength verification studies. This project is expected to be a feasibility study, as such it focuses on finite element modeling, small scale prototyping, mixture design, and exploratory testing rather than construction or delivery of a working bridge system.
2021
MarTREC 6017: Development of Rapid Setting Soil-Cement Mixture Designs and Performance Testing
This project builds upon findings from a previous MarTREC project that proved that BCSA cement could be applied to soil-cement mixing (in place of portland cement), speeding up strength gain significantly. The proposed work would narrow down the design and appropriate use of this material, developing mixture proportioning guidelines and investigating its durability with an emphasis on its use in waterway applications (e.g., levee construction and repair, slope protection, erosion protection, seepage reduction). In addition to standard soil and soil-cement properties determination, strength testing, freeze-thaw testing, wetting and drying testing, permeability testing, and erosion testing will be performed. The result will be new guidance on how to effectively use BCSA soil cement for rapidly deployable, long lasting repairs to soil structures. This knowledge could also be used any time faster construction of stabilized soil structures is needed.
Advanced Concrete Research and Development for Military Applications
The goals of this project are to develop alternative testing and mixture design solutions to military infrastructure problems related to concrete. This includes developing concrete mixtures with alternative cements for a variety of applications, developing new ASR mitigation strategies and test methods, and creating new self-stressing UHPC mixtures. The work in this project is divided into 5 tasks which involve multiple researchers in the Department of Civil Engineering at the University of Arkansas.
ACI Foundation - Concrete Research Council: Stress-Strain Analysis of BCSA Cement for Structural Applications
The proposed work has three objectives. The primary objective of this work is to develop an appropriate value of ultimate compression strain for BCSA cement concrete. The research will also investigate the stress distribution in BCSA concrete at the nominal moment capacity. Finally, axial compressive stress-strain response will be measured for BCSA concrete at different ages. These results will promote confidence in the structural performance of BCSA cement concrete and will also develop new information that can be used to design structures with BCSA cement more efficiently. This work can be an example for investigating flexural performance of other alternative cements.
Flexural testing set up for measuring the stress-strain response of BCSA cement concrete
Specimen Failure in Slow Motion
2019
CTS Cement Manufacturing Corporation Gift
CTS Cement Manufacturing Corporation is supporting students who are interested in studying Belitic Calcium Sulfoaluminate cement at the University of Arkansas. At the moment, these students are studying mix proportioning guidelines for BCSA cement, the effects of set retarders, and mechanical properties.
2018
Arkansas/Oklahoma Chapter American Concrete Pavement Association Gift
The Oklahoma/Arkansas chapter of the ACPA pledged to give $100,000 per year for 5 years to support concrete pavement related initiatives. This money is being used to support students who are interested in studying concrete pavements.
The first students to be supported by this generous gift are Casey Jones (advised by Dr. Micah Hale), and Yancy Schrader. Currently they are working on understanding calcium oxychloride formation and mitigation in concrete pavements, and improving upon test methods to categorize fly ashes based on their susceptibility to de-train air from concrete.
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