This Faculty Early Career Development (CAREER) Program grant will lead to the development of new internal curing agents to be used for the creation of high-performance concrete that has increased strength and durability. High-performance concrete is prone to early-age shrinkage and the subsequent formation of cracks within the system, resulting in concrete structures with significantly reduced strength and lifetime. To combat this problem, water-filled internal curing agents are added to the concrete mixture. As the concrete cures, the agents release the stored water and fuel the curing reaction, eliminating the early-age shrinkage and cracking. This award supports fundamental research on the chemical and physical structure of hydrogel-based internal curing agents in order to develop new composite hydrogels (water-based jelly-like materials) that not only release water to promote internal curing but also chemically enhance the curing reaction and refine the resulting concrete microstructure. These new internal curing agents will result in concrete with increased strength and corrosion resistance, allowing for the aging infrastructure in the U.S. to be repaired and replaced with concrete that has greater performance and reduced economic and environmental costs over the increased lifetime of the concrete. Therefore, results from this research project will directly benefit the U.S. economy as well as the well-being and safety of the general population. This project will also provide engineering students with the multidisciplinary education and training required to overcome performance barriers in infrastructure materials as well as increase societal awareness of how materials research can address important challenges in infrastructure construction.
The creation of a new class of hydrogel-based internal curing agents that simultaneously enhance the curing reaction and refine the concrete microstructure is only possible through bottom-up synthetic design informed by a fundamental understanding of molecular-level structure-property relationships. There is a critical need to identify how the material properties of hydrogel-based internal curing agents used in high-performance concrete are influenced by the molecular structure of the hydrogel and the interactions of the hydrogel with the concrete and pore fluid. To address this critical need, model superabsorbent polymer-pozzolan composite hydrogels will be custom synthesized by the research team to determine how the physical and chemical structure of the composite hydrogels directly controls the swelling mechanisms and mechanical properties of the hydrogels, the workability of hydrogel-cement mixtures, and the resulting microstructure and strength of internally cured concrete. Research activities will involve rheophysical experiments to determine local flow profiles of hydrogel-cement mixtures as well as advanced imaging of microstructural changes in early-age mixtures.
