低浓度CO2条件40℃环境对水泥胶砂早期碳化与水化反应进程影响研究OA

In response to the low-carbon development strategy for building materials,this study explores the optimization path for early-age performance of cement-based materials under low-concentration CO2 conditions.Cement mortars were subjected to CO2 curing at 3%(volume fraction)concentration and 40℃for 2,6,and 12 h to investigate the effects of the carbonation-hydration synergy on mechanical properties,microstructure evolution.The results show that the comprehensive performance of cement-based materials is optimal after 6 h of carbonation,with a 28 d compressive strength of 58.6 MPa—approximately 15.1%higher than that of the purely hydrated sample.At this stage,the amount and crystallinity of CaCO3 reach their maximum,and the proportion of calcite increases significantly.Mercury intrusion porosimetry results reveal that 6 h carbonation effectively refines the pore structure of the specimen surface layer,reducing porosity to 21.8% and enhancing compactness and stability of the material.However,extending the carbonation time causes deterioration of the surface pore structure,leading to reduce strength due to over-carbonation.