碳化对镁渣砂浆强度和微观结构的影响

Strength and Microstructure of Mortars Prepared with Magnesium Slag after Carbonation

采用CO_2养护加速碳化镁渣砂浆,制备了低碳胶凝材料。研究了水灰比和碳化龄期对碳化镁渣砂浆的力学性能及微观结构的影响。结果表明:在CO_2浓度为99.9%、压力为0.1 MPa、温度为23℃的碳化养护条件下,水灰比为0.4的镁渣砂浆碳化14 d后,抗压强度是其碳化前强度值的9.9倍,延长碳化时间有利于强度的提高。水灰比对碳化砂浆强度影响显著,低水灰比试件碳化后强度提高更多。通过微观分析发现,碳化养护提高镁渣砂浆强度的原因是,碳化后生成大量的CaCO_3,使试件更加致密,孔隙率降低。

Low carbon cementitious materials were prepared via carbonating magnesium slag mortars. The effects of water to cement ratio and carbonation curing duration on the compressive strength and microstructure of magnesium slag mortars were investigated. Results show that, the compressive strengths of mortars with a water to cement ratio of 0.4, after carbonation curing in CO2 with a concentration of 99. 9 % and gas pressure of 0. 1 MPa at 23 ℃ for 14 d , are increased by up to 9. 9 times compared to those mortars without carbonation curing. The increase of carbonation curing duration increased the compressive strengths of the mortars. The influence of water to cement ratio on the strength of mortars was remarkable.The strength of specimens with lower water to cement ratio increased more after carbonation. According to microstructure analysis, it was found that the treatment of CO2 enhanced the microstructures densification and decreased the amount of relatively coarse pores and total pore volume due to the formation of calcite （CaCO3）.