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开发新型水泥和其它低碳胶凝材料是水泥工业CO2减排的有效途径。采用CO2养护,加速碳化活性MgO、CaO、粉煤灰和水泥四元组分配制的砂浆,制备低碳胶凝材料,研究碳化对砂浆力学性能和微观结构的影响。结果表明:在浓度为99%、压力为0.55 MPa的CO2气体条件下碳化处理3~9 h后,砂浆抗压强度提高了1.1~4.6倍。提高碳化温度、延长碳化时间均有利于砂浆强度的提高,且温度对砂浆强度的提高影响更为显著。碳化后生成大量碳化产物碳酸钙CaCO3和碳酸钙镁CaxMg1-xCO3,使得砂浆p H值降低、试件更加致密,砂浆试件中大孔数量明显减少,总孔隙率显著降低。
Developing new types of cement and other low-carbon cementitious materials is an effective way to reduce CO2 emissions in the cement industry. Carbon dioxide curing and accelerating carbonization activity of mortar containing MgO, CaO, fly ash and cement quaternary constituents were used to prepare low-carbon cementitious materials. The effects of carbonation on the mechanical properties and microstructure of mortar were studied. The results show that the compressive strength of mortar increased 1.1 ~ 4.6 times after being treated for 3 to 9 hours under the condition of CO2 gas concentration of 99% and pressure of 0.55 MPa. Increasing the carbonization temperature and extending the carbonization time are all conducive to the improvement of the mortar strength, and the temperature has a more significant effect on the mortar strength improvement. After carbonization, a large amount of carbonates CaCO3 and CaCO3-CaxMg1-xCO3 were produced, which decreased the p H value of the mortar and made the specimens more dense. The number of macropores in the mortar decreased obviously and the total porosity decreased significantly.