按照我国低pH值硫酸盐的特征,配制pH=4.0的模拟溶液;通过室内干湿循环加速腐蚀试验,研究低pH值下矿渣粉等量取代水泥为15%-85%时浆体的抗硫酸盐侵蚀性能。研究结果表明:浆体的破坏主要是H^+和SO4^2-共同作用的结果,其破坏过程是从外至内被逐层溶蚀,导致膨胀破坏;H^+导致浆体水化产物脱钙,促使试件溶解,SO4^2-与Ca^2+反应生成膨胀产物石膏,加速试件破坏过程;掺入矿渣粉对水泥浆体抗低pH值硫酸盐侵蚀是有利的,而且随着矿渣粉掺量的增加,其外观保持能力逐步提高。综合考虑掺有矿渣粉净浆试件的各项性能,矿渣粉适宜掺量取45%左右。
Sulfate resistance of cement paste containing 15%-85% slag powder at low pH value was studied through accelerated soaking dry/wet cycles test, and the simulating solution was developed according to the sulfate characteristic at pH=4.0. The test results show that the deterioration of specimens is caused by H^+ and SO4^2- together, the corrosion process of specimens is the dissolution and expansion from surface to inner; H^+ makes the decalcification of hydrate products, so causes the dissolution of specimens, and SO4^2- reacts with Ca^2+ to generate gypsum, which accelerates the deterioration of the specimens. The admixture of slag powder is favorable to the sulfate resistance of portland cement paste at low pH value, and when the paste has higher slag powder replacement, the specimens have better appearance. Considering the whole performance of the specimens, the replacement of slag powder is about 45%.