SBIR Phase II: Developing scale-up manufacturing of engineered waste coal ash based lightweight aggregate for concrete applications

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The broader/commercial impact of this Small Business Innovation Research (SBIR) Phase II project seeks to increase the accessibility of construction lightweight aggregate (LWA) for the concrete industry using a thermodynamics-guided technology to locally produce a cost-effective and engineered LWA from waste coal combustion ash (W-CCA). The traditional LWA manufacturers are only available in few locations and states in the U.S. due to the manufacturers’ raw materials dependency, and therefore, LWA customers (e.g., ready-mix concrete suppliers) in some regions pay more than 70% of the LWA price to transport the LWA hundreds of miles to their plants. At the same time, coal ash landfills are abundant and are scattered around the country. According to the EPA, more than 500 W-CCA landfills are leaching toxic substances into the groundwater at levels exceeding federal safe standards due to improper landfill construction and management. The consequence of these contaminations is continuous damage to the environment, groundwater, and human health. By implementing this technology to produce an engineered LWA from W-CCA locally, both the supply chain issue of LWA and the environmental damage of W-CCA accumulated in the landfills will be alleviated.This project’s goal is to scale up manufacturing of a waste coal combustion ash (W-CCA) based lightweight aggregate (LWA), designed through a thermodynamics-guided technology. The product will be produced through a two-step approach to demonstrate the successful use of the LWA for lightweight concrete production. This technology addresses the main challenge of LWA production from W-CCA which is chemical composition variability in the feedstock from one landfill to another. The engineered LWA is based on the chemical composition of the raw W-CCA and the required conditions for the formation of a porous LWA. The project will consider formation of the optimal amount of molten phase, the appropriate viscosity for partially molten ash, and the gas release from the ash to form the pores. To achieve this project’s goal LWA manufacturing at batch scale will be developed and tested and the properties of the product will be assessed according to relevant American Society for Testing and Materials (ASTM) standards to demonstrate compliance. The product LCA will be used for structural lightweight concrete preparation and characterization and the team will develop a continuous manufacturing system for LWA production at tonnage scale. Finally, field scale concrete will be cast and characterized using the produced LWA at tonnage scale.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.