Carbon dioxide cured building materials as an approach to decarbonizing the calcium carbide related industry

Storing CO2 in building materials is an effective way to utilizing CO2 and mitigating climate change. This study presents a new approach connecting the decarbonization of the coal-to-chemical industry with the production of CO2 cured building materials. This approach uses calcium carbide residue (CCR), a byproduct of the CaC2-to-acetylene process, as an alternative lime source for CO2 sequestration, and it is generally applicable to all scenarios where alternative lime wastes are available. For the first time, the feasibility of achieving two cementation mechanisms, i.e., lime carbonation and lime-silica reaction, in one autoclave was demonstrated at the industrial level. By doing so, the building materials prepared are capable of sequestering up to 20% CO2 by the weight of raw binders, meanwhile being applicable for structural usage. This approach facilitates the reuse of various solid and gaseous wastes associated with the coal-to-chemical industry. More importantly, the low-carbon nature of industrial byproducts serving as raw materials and the vast CO2 taken up via CCR carbonation makes the materials prepared CO2 negative. Considering only the calcium carbide industry of China, this approach brings an opportunity to mitigate 129 Mt to 311 Mt CO2 eq global warming potential by 2050. •CO2 cured building materials prepared from calcium carbide residue are CO2 negative.•Integrating pozzolanic reaction and lime carbonation in one autoclave is industrially feasible.•This material recovers up to 7.5% GWP associated with CaC2-derived PVC production.•Applied in China, this approach can mitigate up to 311 Mt CO2 eq GWP by 2050.