Test Study On The Salt Resistance Of Cement Concrete

Since the reform and opening up in china,the pavement of cement concrete has made great progress.But,there are still some problems in the pavement of cement concrete,such as the diseases of cracking,void,pumping,faulting and so on.These diseases have affected the service life and pavement quality.There are various reasons to cause these diseases,but the lack of frost resistance of cement concrete must be one of the most important reasons,especially for the cold regions in the north.In the weather of heavy snow,to ensure the safety of vehicle,it was necessary to bestrew the salt(mostly chlorine),but the salt aggravates the damage of concrete.Therefore,the composition and modification of cement concrete were analyzed in this paper,the performance of salt frost resistance and modification mechanism for cement concrete were studied.Though optimizing the composition of concrete,the performance of frost resistance for concrete was improved,and thus achieving the goal of extending the service life of the pavement.Based on the specifications,the requirements of materials' qualities for concrete were put forward.According to the requirements of strength and construction quality for cement concrete,the proportion of material for concrete was determined.Firstly,choosing the appropriate material and dosage,carrying out the freeze-thaw cycles test and flexural strength test.In the tests,the salt solution concentration was 3%,the number of freeze-thaw cycles was 200,and relative modulus,mass loss and flexural strength loss under freeze-thaw cycles were obtained.Then,the water-cement ratio,air entraining admixture,mineral admixture,fibers and nanometer material on the anti-salt properties of concrete were analyzed and its action mechanism was analyzed.Based on the analysis of pavement service life,the effect of the water-cement ratio,air entraining admixture,mineral admixture,fibers and nanometer material on the economic benefit for cement concrete were analyzed.According to the analysis of pavement service life,the BP(Benefit Parameters)was put forward,all the five kinds of modified concrete for economic benefit were compared.Based on the analysis of frost resistance mechanism,the factors included the raw material,water-cement ratio,air entraining admixture,mineral admixture,fiber and nanometer material,construction methods and maintenance quality to improve the performance of salt frost resistance for concrete were analyzed.At last,the suggestions for the design and construction of pavement to increase its service life in salt frost region were put forward.