硅灰对水泥净浆抗硫酸盐侵蚀性能的改善作用

将水泥净装试件在5%N、50;溶液中长期浸泡，用试件强度随浸泡时间的变化和试件中物相的XRD分析，研究了硅灰对水泥净泉抗硫酸盐侵独性能的影响。在N气S久溶液侵性下，普通硅酸盐水泥净装试件强度随浸池时间先增长，然后急剧降低;外观和XRD相分析表明，其原因是由于形成了膨胀性钙矶石，造成试件开裂破坏;加入硅灰的水泥净菜试件强度损失明显减小，尤其是抗折强度没有降低，其抵抗强度下降系数还略有增加;原因是由于硅灰的稀释作用和火山灰效应减少了水泥净泉中Ca(OH):的量，从而降低了水泥净莱试件在硫酸盐溶液侵蚀下形成的膨胀性钙矶石的量。因而，硅灰时水泥混凝土杭硫酸盆侵独性能有改善作用。

IMPROVEMENT EFFECT OF SILICA FUME ON THE CEMENT PASTE IN SULFATE ATTACK

The behavior of silica fume cement paste against sulfate at-tack has been studied. The experimental method used is long immersed tests, in which the hardened cement paste specimens are immersed in the 5% NazS04 solution. The strength change of the specimens with the time has been measured and phases of the specimens have been analyzed by XRD. Results indicate thatthe strength of the OPC paste specimens increases at an early stage and then decreases greatly following sulfate attack. The appearance and XRD analysis have indicated that the cause of their deterioration is the expansion of ettringite and the obvious reduclion of strength loss in silica fume cement paste specimens. The bending strength does not reduce, while the decrease coefficient of strength increases a little. The factor is that the Ca( OH ) 2 inthe cement paste is reduced and the formation of expansive ettringite against sulfate attack is decreased yet by the dilute effect and the pozzolanic reaction of silica fume. Therefore, the silica fume may be mixed into cement concrete to improve their anti-sulfate attack.