Acceleration of chelator on mineralization reaction of cement paste at different CO2 pressures

Abstract

In order to further improve the mechanical properties of CO2-cured cement paste, effects of chelator on the compressive strength of cement paste cured under different CO2 pressures were investigated, and the mechanism of chelator in accelerating the mineralization reaction was deduced from the analysis of the degree of mineralization reaction, microstructures, and phase compositions, with the contribution of chelator in reducing the net CO2 emissions of cement industry being evaluated. The results showed that the use of chelator could significantly enhance the compressive strength of cement paste cured at different CO2 pressures compared with other methods for improving the compressive strength of CO2-cured cement paste, and the compressive strength of cement paste cured for 48 h at 0.1 MPa and 0.4 MPa CO2 could be enhanced by 23.2 % and 9.4 %, respectively. Chelator could migrate Ca2+ from smaller pores and pore channels to larger pores, decreasing the Ca2+ content and degree of mineralization reaction in smaller pores and pore channels, avoiding the blockage of the stomata by generated CaCO3, and allowing more CO2 to penetrate and diffuse into the cement paste, thereby promoting mineralization reaction and significantly improving compressive strength of cement paste cured at atmospheric pressure. The use of chelator in mineralization curing cement-based materials could further reduce net CO2 emissions from cement production, making significant contribution to the advancement of mineralization curing technology and environmental sustainability.