I-Corps: Carbon-negative supplementary cementitious materials for carbon-neutral concrete

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The broader impact/commercial potential of this I-Corps project is the conversion of a broad range of negative-value and low-value solid wastes into high-value, blended, supplementary cementitious material (SCM) through enhanced carbon dioxide (CO2) mineralization. SCM is a commodity used in the cement and concrete industry. The commercial potential of this technology is supported by three current industry trends. First, the grand challenge of carbon reduction will require breakthrough technologies that can be deployed at gigaton scale. Second, the cement/concrete industry is a major source of CO2 emissions and is seeking alternative SCMs to replace cement for deep decarbonization. Third, various aluminosilicate solid wastes need to be beneficially used to mitigate their ecological burden. The proposed technology will simultaneously address these three demands.This I-Corps project is based on the production of blended supplementary cementitious material (SCM) through upcycling of alkaline aluminosilicate solid wastes. These wastes contain oxides of alkaline earth metals and transition metals. The proposed approach enhances the dissolution of these metal elements and converts them into carbonate particles through controlled carbonation (carbon dioxide uptake). Byproducts of this process are amorphous aluminosilicate phases and impurities. Recent research results have shown that if proportioned properly, carbonates (such as ground limestone or dolomite) and amorphous aluminosilicate (such as calcine clay) can act synergistically to replace up to 50% of cement in concrete production, without compromising the performance of concrete. What differentiates the proposed approach from emerging technologies is that the components (carbonates and aluminosilicate) forming the blended SCMs are produced from solid waste through a carbon-negative process, instead of excavation of natural resources. Simulation and experimental results have shown that the resultant blended SCMs, when used to replace part of cement, can change of composition but yield comparable pore structures and mechanical properties to normal cement-based materials such as concrete.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.