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.