CO 2 mineralization fixation and performance enhancement of silicate cement paste

Abstract Silicate cement has a huge market demand because it is widely used in construction, transportation and other infrastructures. It has become a current research hotspot how to ensure its performance while meeting the requirements of environmental protection. To this end, the study used PO42.5 silicate cement as the base material, and adopted the solid-carbon enhanced mixing method by introducing gaseous CO 2 and solid CO 2 (dry ice) as the mineralization medium. The effects of CO 2 mineralization on the hydration behavior and mechanical properties of cement paste were systematically evaluated. The experimental results showed that the mineralization rate and carbon sequestration capacity of the ready-mixed concrete samples were optimal when the water-cement ratio was 0.2, and the final carbon sequestration rate was 8.1 wt%. Under 10% silica doping, the optimal water-solid ratio was 0.22, the reaction rate constant was 0.163 min −1 , and the delay time was shortened to 1.1 min. In addition, the ready-mixed concrete samples showed limited CO 2 uptake when conventional mixing methods were used. The overall carbon sequestration reaction rate was low, and the final carbon sequestration rate was 0.68 wt% of the cement mass. In contrast, the CO 2 uptake capacity was significantly enhanced when using the sequestration-enhanced mixing method, and the final carbon sequestration rate reached 3.18 wt%. In conclusion, the carbon sequestration mixing method designed by the study can significantly improve the CO 2 absorption efficiency and mineralization rate of cement paste. Moreover, it can also provide a practical technical path to realize the development of green and low-carbon building materials.