Project Summary

To prevent high-performance concrete from shrinking and cracking during curing, hydrogel-based internal curing agents can be incorporated into cement mixtures to fuel the hydration reaction and ultimately create concrete with increased strength and durability. In this CAREER project, involving researchers in the School of Materials Engineering at Purdue University, polymer hydrogel particles were designed and used as internal curing agents in high-strength cement and mortar mixtures. Custom synthesized hydrogel particles were developed to determine the relationships between the chemical and physical structures of the hydrogel particles and their overall internal curing performance in cement and mortar mixtures. Research outcomes demonstrated that hydrogel-based internal curing agents improved the stability, strength, and expected service life of high-performance cementitious mixtures.

Intellectual Merit

Core Disciplinary Impacts

Many construction practitioners commonly assumed that hydrogel-based internal curing agents were chemically inert within concrete mixtures. However, results from this project have shown that instead, the presence of hydrogel particles of certain compositions - including acrylamide-rich particles and composite particles containing silica - encouraged the formation of high-strength inorganic phases within the cement microstructure which would result in a more dense and durable concrete. Additionally, it was discovered that the presence of multivalent cations that naturally occur in hydrating cement actually decreased the swelling capacity and altered the sorption kinetics of the hydrogel particles to the point where some hydrogel compositions displayed fast deswelling behavior and the formation of a mechanically stiff outer shell. Project personnel also participated in an international round-robin collaboration to evaluate the current methods that are used to characterize hydrogel absorbency.

Cross-Cutting Concepts

Research outcomes have improved the fundamental understanding of the attractive and repulsive interactions between ions, organic molecules, and inorganic particles in aqueous environments. A better understanding of these interactions could further facilitate the development of thin-film sensors, drug delivery agents, scaffolds for regenerative medicine applications, and water separation membranes.

Dissemination

Research outcomes were presented to students, researchers, and practicing engineers and scientists at annual meetings of the American Concrete Institute, the Cements Division meeting of the American Ceramic Society, the American Chemical Society, the Materials Research Society, and international meetings organized by RILEM as well as at U.S. companies, national labs, and universities. Results were also published in peer-reviewed journals within both the construction materials and chemical sciences communities, including Materials and Structures, Cement and Concrete Research, Gels, Journal of Applied Polymer Science, and ASTM Advances in Civil Engineering Materials. Additionally, one U.S. patent resulted from this project (Erk, U.S. Letters Patent 10,081,573).

Broader Impact

Societal Benefit

Hydrogel-based internal curing agents can be used to create high-performance concrete structures that have increased strength and service life while preserving the overall low-cost of cement and thus the wide-spread use of concrete in developing countries. Thus, as internally cured high-performance concrete is used to repair and replace aging infrastructure in the United States and abroad, the increase in material quality will lead to long-term economic and societal gains. Such actions could potentially prevent severe devastation due to concrete failure from natural disasters around the world, such as the destruction following the 7.0- and 7.2-magnitude earthquakes in Haiti in 2010 and 2021 that was directly linked to poor-quality concrete used for housing and other buildings.

Workforce Development

Infrastructure-focused materials engineers are needed to collaborate with existing practitioners to develop new construction practices and building materials that are economical, durable, and sustainable. Over the course of this project, approximately 20 undergraduate and 10 graduate students at Purdue were immersed in a multidisciplinary environment, involving disciplinary core ideas from chemistry and polymer science, fused with technical and practical knowledge from civil, materials, and mechanical engineering disciplines. Student researchers most closely affiliated with this project successfully obtained a total of 13 Bachelors, 2 Masters, and 4 Doctorate degrees.

Educational Outcomes

A new cross-disciplinary course on the use of chemical admixtures in concrete was developed for upper-level undergraduate and graduate students in engineering at Purdue. A multi-year partnership was also established with the Pre-Engineering Program at Ivy Tech Community College in Lafayette, Indiana to develop curriculum and design activities related to the engineering design process, material technology, and technical communication. Outcomes from this partnership were presented at the 2018 meeting of the American Society of Engineering Education.

Engagement and Outreach Outcomes

Project personnel were involved in a variety of activities in the local community, including leading science demonstrations for elementary students at a local science center and presenting information on interdisciplinary undergraduate research opportunities and successful technical communication strategies to freshman and sophomore engineering students at Purdue. The project also broadened the participation of underrepresented groups in STEM by involvement of project personnel in activities targeting preK-12 students in partnership with the Women in Engineering Program at Purdue.

Last Modified: 11/09/2021
Modified by: Kendra Erk