SBIR Phase I: Sustainable Engineering of Lightweight Aggregate for Concrete Use from Waste Coal Combustion Ash

The broader impact of this SBIR Phase I project is two-folds: (1) increasing the accessibility of construction lightweight aggregate (LWA) for the concrete industry and (2) conversion of waste coal combustion ash (W-CCA) to value-added products (i.e., construction LWA). Yearly, about 100 million tons of coal combustion ash is produced in the US, of which only about 60% is recycled and the rest is moved to the landfills. This imposes risks to human health and the environment. Meanwhile, accessibility of construction LWA that is traditionally produced from clay, slate, and shale is challenging for the concrete industry in some states due to the absence of local construction LWA manufacturers. Therefore, LWA must be imported from elsewhere in the country, increasing (i) the final cost for the material and (ii) greenhouse gas emission due to transportation. With an abundance of W-CCA landfills scattered throughout the US, LWA can be produced from this material near the landfill sites to increase the local accessibility of construction LWA for the concrete industry. By implementing this technology, the environmental impact of W-CCA will be reduced, natural resource consumption will be prevented, CO2 emission associated with material transportation will be reduced, and users can save money by having access to local construction LWA. This Small Business Innovation Research (SBIR) Phase I project addresses hurdles associated with manufacturing a novel porous lightweight aggregate (LWA) produced from waste coal combustion ash (W-CCA). The melting properties of W-CCA enable the production of construction LWA with superior engineering properties, including increased water absorption/desorption capacity and concrete workability relative to traditional LWA. The deliverables of this project include: (i) development of a LWA with desired sintering properties during pilot-scale production to assure technical feasibility of scaling-up the proposed technology, (ii) optimization of pilot-scale rotary kiln parameters translatable to large-scale production, (iii) demonstration of the superior engineering properties of LWA for concrete applications produced at lab pilot-scale, and (iv) demonstration of the non-leachability of W-CCA based LWA in encapsulated concrete applications. 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.