Research Thrust I
Multi-scale investigations of innovative materials for civil infrastructure applications
The research projects and activities in this thrust are centered on the importance and growing need for the incorporation of new materials into building and bridge structures for not only achieving sustainability goals, but also transforming the safety and resiliency of the built environment against extreme events. While the number and variety of materials developed for the building and bridge industry continue to expand, as do the advancements in their complexities and the knowledge and training required for their proper use.
Example sponsored and exploratory research projects include:
Non-Proprietary Ultra-High Performance Concrete (UHPC)
Materials and Additive Manufacturing Solutions for Steel Corrosion
High-Performance Fiber-Reinforced Concrete (HPFRC)
Agricultural-Based Phase Change Materials (PCM)
Non-Proprietary Ultra-High Performance Concrete (UHPC)
UHPC has received significant attention for structural applications, especially where superior strength and durability characteristics are critical. Although the high strength and durability of UHPC permit the production of thinner/lighter structural elements with a longer service life and less maintenance needs, the use of UHPC is found cost prohibitive in many projects because commercially available/proprietary mixtures can cost up to 5 times of conventional concrete mixtures. To address this issue, our research group works to develop cost-effective UHPC mixtures. For this purpose, the specific objectives are to design non-proprietary UHPC mixtures made with locally available materials, test the performance of the mixtures at both fresh and hardened stages, and develop a performance-based guideline to utilize non-proprietary UHPC mixtures for various structural components and exposure conditions.
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Materials and Additive Manufacturing Solutions for Steel Corrosion
Steel corrosion has been a long-standing problem, adversely affecting the safety and performance of civil infrastructures in service. The current methods for addressing the corrosion of steel structures can be categorized into two broad groups of preventive and corrective strategies. Despite the variety of methods, however, many of them are proven to be insufficient for structural applications or suffering from a range of constructability and economic issues. To make advancements in preventive strategies, our research group works on the structural and fatigue performance of stainless steel for bridge girders and the incorporation of GFRP bars into bridge decks. For corrective strategies, an exploratory research effort is ongoing to benefit from the additive manufacturing (AM)-assisted spraying methods for the repair and retrofit of corroded steel structures. The outcome of this “high risk-high payoff” effort is expected to lead to the novel methods that build on the growing power of AM and robotic construction to address the corrosion-related issues in steel structures.
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High-Performance Fiber-Reinforced Concrete (HPFRC)
With mounting demand for enhancing durability and extending the service life of civil infrastructures made of concrete, HPFRC can be a reliable solution, combining the excellent durability properties of high-performance concrete (HPC) with the strain-hardening and crack preventing/bridging characteristics of fiber reinforced concrete (FRC). To provide an alternative for conventional concrete mixtures, our research group works to develop HPFRC mixtures that can deliver the desired performance characteristics in both short and long term. For this purpose, current HPC mixtures are improved with the addition of fibers of various type, geometry, and dosage. Furthermore, other methods of crack mitigation, such as using shrinkage-reducing admixtures and shrinkage-compensating cements are examined. Laboratory and field tests are performed to ensure the adequate resistance of developed mixtures to early-age cracking, transportation of aggressive ions, freeze/thaw cycles, and abrasion, while maintaining proper workability, strength, and toughness characteristics for various infrastructure applications.
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Agricultural-Based Phase Change Materials (PCM)
Considering that concrete is the most widely used construction material in the world for civil infrastructure applications, development of functional, low-cost, and energy-efficient concrete structures directly contributes to a sustainable built environment. In this area of research, our research group has capitalized on regional resources to introduce agricultural-based phase change materials (PCMs) designed to improve the energy efficiency of concrete panels. Based on a comprehensive set of application-specific performance criteria, appropriate PCMs have been identified and tested. A separate effort is now ongoing on the development of an efficient encapsulation technique to incorporate the PCMs into the concrete mixture. The thermal properties and structural characteristics of the PCM-concrete matrix are the main aspects of interest. With holistic material- and system-level investigations, we work with ISU’s BioCentury Research Farm to scale up and transfer this technology.
