Complete recycling of concrete waste to produce carbon-negative geopolymer concrete

This project will develop innovative and sustainable technology for complete recycling of concrete waste, including recycled concrete aggregates and recycled concrete fines, to produce carbon-negative geopolymer concrete. The successful completion of this project will promote complete recycling of concrete waste in an environmentally friendly and sustainable way to avoid the use of energy-intensive and high-carbon-footprint. It will also save on monetary and environmental costs related to transportation and disposal of concrete waste, reduce the demand for using natural sand and aggregate, and sequester carbon dioxide. Additional societal benefits will be realized through outreach and educational activities including Summer Engineering Academy and K-12 mentoring programs, development and display of educational exhibits at Biosphere 2, and mentorship of undergraduate and graduate students. The approach of this project is based on the innovative integration of carbonation and geopolymerization, which could fundamentally revolutionize the conventional concept for recycling concrete waste. The research is guided by four hypotheses. These hypotheses address the fundamental mechanisms for complete recycling concrete waste to produce carbon-negative geopolymer concrete. To test them, the project will pursue four research objectives. They include elucidating how the carbonation of recycled concrete fines affects the geopolymerization process and enhance the geopolymer properties, obtaining a fundamental understanding of the interaction between the carbonated recycled concrete aggregates and the geopolymer, studying the performance of geopolymer concrete produced from fully recycled concrete waste through carbonation and geopolymerization, and evaluating the environmental impact and techno-economic feasibility of producing geopolymer concrete from fully recycled concrete waste through carbonation and geopolymerization. The research will not only evaluate macroscale behavior, but also investigate micro/nanoscale morphology, composition, and properties. Evaluation of the environmental impact and techno-economic feasibility will also be performed. Successful completion of the project will advance knowledge in mineral carbonation, geopolymerization, and concrete waste recycling. 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.