高地温对超细复合掺合料胶凝体系的影响

Effect of high ground temperature on the gelling system of ultrafine composite admixture

通过实验室近似模拟高海拔地区高地温环境,研究超细复合掺合料对水泥基胶凝材料力学性能、体积稳定性、孔结构的影响,分析在不同温度下超细复合掺合料对水泥的最优取代率,结合微观手段分析超细复合掺合料最优掺量时胶凝体系的反应机理。结果表明:掺加超细复合掺合料能提高水泥基胶凝材料的力学性能,随着养护龄期的延长,最优取代率的抗压强度能够提高10%~21%,在高温下强度增长缓慢;超细复合掺合料体系的收缩率表现优于纯水泥体系,在适当高温环境下可保持体系稳定,但80℃的养护温度会增大体系的体积收缩率;超细复合掺合料能降低体系的平均孔径,提高密实度,生成更多钙矾石、水化硅酸钙等水化产物。

The effect of superfine composite admixture on the mechanical properties,volume stability and pore structure of cement-based cementing materials was studied by simulating the high ground temperature environment at high altitude in the laboratory.The optimal dosage of superfine composite admixture at different temperatures was summarized and analyzed.The reaction mechanism of superfine composite admixture in cementing system at optimal yield was analyzed by combining microscopic means.The results show that the addition of superfine composite admixture can improve the mechanical properties of cement-based cementing materials.With the extension of curing age,the compressive strength of the optimal admixture can be increased by 10%~21%,and the strength increases slowly at high temperature.The shrinkage rate of the superfine composite admixture system is better than that of the pure cement system,and can keep the system stable under proper high temperature environment,but the volume shrinkage rate of the system will increase when the curing temperature is 80℃.The superfine composite admixture can reduce the average pore size of the system,improve the compactness,and generate more hydrated products such as ettringite and hydrated calcium silicate.