Design of C2S-CS low-calcium system for synergistic improvement of CO2 sequestration capacity and mechanical properties

Abstract

Low-calcium minerals exhibit significant potential as energy-efficient binder clinker materials, characterized by reduced emissions and enhanced carbon sequestration through accelerated carbonation curing. However, traditional low-calcium binders typically utilize one or two minerals in a straightforward compound form as clinker, resulting in elevated costs, excessive resource consumption, and suboptimal performance. This study developed a novel C2S-CS low-calcium system that integrated γ-C2S, β-C2S, and CS in specific proportions based on their characteristics, utilizing Simplex-centroid designs. Contour maps achieved to assess relationship between performance and mineral composition, while interaction mechanisms were investigated through carbonation products and reaction heat analysis. Furthermore, optimum proportion range of C2S-CS system can be synthesized efficiently and environmentally from solid waste wollastonite tailings in a single step. The results demonstrated that the designed system achieved synergistic improvements in CO2 sequestration capacity and mechanical properties. After 24 h of carbonation curing, it attained a compressive strength of 129 MPa, sequestered 217 kg/t CO2, and exhibited satisfactory durability. This study provides valuable insights for the practical production of low-calcium binders and reveals opportunities for developing sustainable building materials for eco-friendly construction.