Development of novel highly carbonation-reactive fibrous α-wollastonite binder via crystal transformation activation

This investigation demonstrates a pioneering approach for synthesizing highly carbonation-reactive fibrous α-wollastonite (α-CS) binder through crystal transformation activation of natural wollastonite, resulting in negative CO₂ emission while achieving superior mechanical properties. The rapid crystal transformation activation from natural CS to α-CS was accomplished at 1200 °C, markedly enhancing carbonation reactivity while maintaining the inherent fibrous morphology. The transformed α-CS exhibited remarkable performance improvements compared to natural CS, with CO₂ uptake increasing by 1.04 times, while compressive and flexural strengths were enhanced by 13.65 and 5.76 times, respectively. Enhanced carbonation reactivity was attributed to reduced Ca-O bond energy, increased crystal defect concentration, and expanded reactive surface area. The crystal transformation activation methodology presents significant advantages over conventional solid-phase sintering by eliminating carbonate decomposition and the associated sintering process, thereby substantially reducing fossil fuel consumption. Additionally, the carbonation curing process facilitates considerable CO₂ sequestration, enabling the development of binders with negative CO₂ emissions.