超细矿渣粉对硅酸盐水泥性能和微观结构的影响

通过掺入不同量的超细矿渣粉,研究其对普通硅酸盐水泥凝结时间、标准稠度用水量以及水泥胶砂流动性和强度的影响。结果表明,水泥浆体的初凝、终凝时间在矿渣粉掺量为5%(质量分数,下同)时有所缩短,而随着超细矿渣粉掺量的增加,初凝时间都有所延长,在掺量为20%时初凝时间最长。然而终凝时间的变化不大,只有掺量为30%时稍有延长;水泥的标准稠度用水量先减少后增加,在掺量为20%时最小;随着超细矿渣粉掺量的增大,水泥胶砂的各龄期抗折强度、3d抗压强度不断提高,7d、28d抗压强度在掺量为20%时达到最大值,之后有所降低。掺入超细矿渣粉后,能通过填充以及与水泥水化产物氢氧化钙发生反应,使水泥中氢氧化钙含量明显降低,水泥微观结构更加密实。

Properties and Microstructure of Portland Cement Added with Ultrafine Slag Powder

Effect of different addition amount of ultrafine slag powder on water consistency, setting time of Portland cement paste and flowability and strength development behavior of cement mortar were investigated. Results showed that both initial and final setting time of the cement paste added with 5%(mass fraction) slag powder shortened and the initial setting time extended while the final remained almost unchanged with the further addition of slag powder. Water consistency increased first and decreased later with the addition of slag powder and reached a minimum value when the slag powder addition amount was 20%. 3 d compressive strength and bending strength at different curing age increased with addition amount of slag powder, while 7 d and 28 d compressive strength reached the maximum at the 20% addition of slag powder. After addition of ultrafine slag powder, content of portlandite in cement mortar decreased significantly by hydration products with portlandite. As the result, the microstructure of cement became more compacting.