硫酸盐侵蚀下石膏形成引起的水泥净浆破坏

Formation of Gypsum Leading to the Destruction of Cement Paste under the External Sulfate Attacking

通过掺加石灰石粉,对长期浸泡在5%(质量分数)Na2SO4溶液中的水泥净浆试件所产生的有害化合物进行了研究.结果表明:在Na2SO4溶液侵蚀下,水泥净浆试件因产生石膏膨胀开裂、表面软化而形成从表到里的破坏,石膏膨胀是其主要劣化方式;水泥净浆破坏机理是石膏膨胀和胶凝物质分解;保持浸泡溶液的pH值,会抑制水泥净浆试件中钙矾石的生成.因此,在水泥混凝土中加入石灰石粉可以检验其抗硫酸盐侵蚀性能.

By the means of the addition of limestone powder, the harmful compound of cement paste caused by the long period immersion in 5% Na2SO4 solution was investigated. Experimental results indicate that under the sulfate attack condition cement paste specimens is split, their sur face is softened and the sample is destroyed from outside to inside, gypsum expansion and cementitious materials decomposition are the main reason for the deterioration of cement paste. The ettringite in cement paste specimens can be controlled by the maintain of pH to a certain value. Therefore, the limestone powder can be mixed into cement concrete as a kind of material to test its anti-sulfate attack property.