改性硅酸盐水泥浆体的耐水性

WATER-RESISTANCE BEHAVIOR OF MODIFIED PORTLAND CEMENT MORTAR

研究了磷铝酸盐水泥(phosphoaluminate cement,PALC)改性的硅酸盐水泥(portland cement,PC)浆体的耐水性及其耐水机理.以胶砂力学强度、净浆耐水性指数、Ca2+及[AlO4]5-的溶出浓度3项指标评价了浆体的耐水性.结果表明:质量分数为3%～5%PALC改性的PC样品经水浸蚀1,90 d后的耐水性指数较PC的分别提高了66.7%和60.8%.改性PC样品水浸蚀1,90 d的抗压强度较PC的分别提高了90.1%和64.5%.改性PC样品浸水1,90 d Ca2+溶出浓度分别为PC的67.9%和66.4%,[AlO4]5-溶出浓度分别为PC的49.10%和50.2%.与PC样品比较,PALC改性PC样品的耐水性提高主要是由于形成了更为稳定的水化产物,而且水化产物凝胶相增多,Ca(OH)2量减低;浆体溶液的ζ电位低以及小于30 nm孔的体积增大.

The water resistance behavior and its mechanism for portland cement mortars and pastes modified by phosphoaluminate cement（PALC） were studied. The mechanical strength of mortars, the water resistance indices of pastes and the dissolving mass concentrations of Ca^2＋ and [AlO4]^5- of the pastes on the exposure age were used to determine the water resistance level. Mortars and pastes prepared with grade 42.5 and 52.5 type Ⅰ portland cement （PC） respectively were used as the controls. The results reveal mainly that upon 1, 90 d exposing in water, the water-resistance indices of specimens modified by 3% - 5% （in mass, the same below） PALC are 66.7 % and 60.8 % respectively higher than that of control PC. The compressive strength of modified ones is 90. 1% and 64.5% respectively higher than that of controls, the dissolving mass concentrations of Ca^2＋ of modified specimens are as 67.9% and 66.4% high respectively as controls, and [AlO4]^5- are as 49.10% and 50.2% high respectively as controls. Comparing with control PC, the high water resistance of modified PC is resulted by high stability of hydrates, by high amount of gel hydrates and low amount of portlandite, by the low ζ potential of the solution in pastes, and by the high volume of pores smaller than 30 nm.