Preparation Of Damaged Concrete To Sulfate Attack

Sulfate attack is one of the main factors that cause concrete materials defectedand lead the performance and service life of concrete structure deteriorated andshortened. In practical application, different factors, such as improper constructionprocess, accidental external forces and natural calamities, will inevitably causevarious degrees of damages to concrete structures. In this case, sulfate attack willmake the damages even worse. Therefore, it is quite necessary to study theresistance of concrete with different damage degrees to sulfate attack.In this paper, the damages to concrete specimens are achieved by prefabricatedexternal loading and the definition of the damage degree of concrete is based onultrasonic wave velocity. The damage degrees are uniformly distributed in0-0.3,and artificially the damage degrees are divided into three ranges,0-0.1,0.1-0.2and0.2-0.3. The sulfate corrosion resistance of C30concrete and damaged concrete wasstudied by dry-wet cycles. The results show that the corrosion resistance ofdamaged concrete to sulfate attack gets poorer compared with the undamagedreference concrete. The sulfate corrosion resistance of concrete with0-0.1initialdamage degree declines slightly and after130dry-wet cycles its relative dynamicelastic modulus is still higher than60%, which equals94%to that of referenceconcrete, so the effect of such small damage could be ignored. However, the sulfatecorrosion resistance of concrete drops significantly when the damage degreeexceeds by0.1and after90dry-wet cycles its relative dynamic elastic modulus islower than60%.The results of our research provide a guideline for the durability evaluation andstructural service life prediction of the damaged concrete structure under sulfateenvironment.