Development of a Novel Lightweight Aggregate with Carbon Sequestration for the Concrete Industry

Solid Carbon proposes to develop a new product with this grant, a lightweight aggregate with sequestered carbon. The aggregate will use point source emissions from pyrolysis to mineralize CO2 in the synthetic aggregate. Pyrolysis is the process through which biomass is thermally treated to form a stable form of biocarbon which is a key ingredient in the proposed lightweight aggregate. Utilizing the point source CO2 emissions will improve the strength of the aggregate through enhanced carbonated curing, while also creating a circular economy using both the biocarbon and the waste emissions of pyrolysis. The team assembled for this project includes an academic partner in the Colorado School of Mines. In the Tunstall Materials Research Laboratory, the academic team will create rapid prototyping of candidate formulations of this novel lightweight aggregate, building on previous research done at the School of Mines, as well as other researchers in the field. There are several novel aspects about the proposed approach, with use of waste products from ready-mix concrete operations and CO2 mineralization being the primary differences. Solid Carbon, the small business involved with this SBIR proposal, will take the candidate inventions through both laboratory testing and simulated production trials. Additionally, the company will prepare the way for commercialization activities in Phase II. Conceptual economics for this product are good. Lightweight aggregates are a premium product with an Average Selling Price (ASP) over 4 times that of standard aggregates and are used in specialty applications such as insulating concrete, topping slabs, and geotechnical applications. Low value pyrolyzed waste carbon can be affordably processed. The construction market has shown an appetite for products that demonstrate high performance with lower embodied carbon (Mordor, 2023). This technology exists today at TRL 2. Bringing this product to TRL 5 is a non-trivial technical challenge. Several candidate stocks will be evaluated during this study and the team will test the resulting products using ASTM C330 Standard Specifications for Lightweight Aggregates for Structural Concrete as the regulatory framework for testing and evaluation. The team will conduct techno economic analysis for candidate feedstocks and processing steps. Risk mitigation strategies will identify both the likelihood of failures and perform consequence analysis. In conclusion, the incorporation of lightweight aggregates with mineralized CO2 in concrete offers a versatile and sustainable solution to address various research challenges. Embracing this innovative approach promises not only to enhance performance but also contributes to a more resilient and ecofriendly construction industry.