Abstract:By the means of the addition of limestone powder,the harmful compound of cement paste caused by the long period immersion in 5% Na_2SO_4 solution was investigated.Experimental results indicate that under the sulfate attack condition cement paste specimens is split,their surface 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.