Research On The Correlation Between The Salt Erosion Conditions And The Degradation Of Cement-based Materials

Erosive salts medium which exist widely in the nature is one of the most important factors affecting the concrete durability and also attract much attention in the durability research area. Based on the already known results and the actual characteristics of concrete suffering salts attack, this paper analysed the degradation mode and property change of the specimens under the conditions of full immersion, half immersion and cycles of wetting and drying, in order to analyse the corresponds between the salt attack conditions and the degradation of cement based materials. Through the results of the tests, it can be known as the following.(1) The progresses and modes of the deterioration of the specimens are basically similar as a whole, in which the specimens began to crack in the end region and then the cracks expand along the edge to the extent that the separated cracks become connected leading to the deterioration of the specimens from the surface to the interior. The test conditions, such as the concentrations and processing modes, have great effect to the speed of the degradation due to the different motivations of degradation.(2) The property changes of the specimens with the increase of the time, such as mass, showed a similar3-stage law, that is, the fast growth stage at the beginning of the experiments and the relatively steady stage (a loss accumulation period) after a transient quick decline, and at last a rapid degradation stage. It can benefit to analyse the performance life of the concrete under the salts attack.(3) Based on the existing experiment methods of the cycle of wetting of dring of sulfate solution, it can make the cycle period extend from24h to48h through extend the time of "wet state", reducing50%the times of the cycle of wetting and drying reaching the same critical state. Thus, simplify the progresses of the experiments.(4) The processing methods of attack solution have obvious correlation with the speed of degradation. In the four methods of full immersion, half immersion, cycle of wetting and drying and half immersion outdoors, the speed of deterioration under the method of the cycle of wetting and drying is the highest and cost least time. What’s more, it’s also the closest to the outdoor conditions.(5) It’s proposed to use the laboratory accelerating tests of cycle of wetting and drying to evaluate the capability of cement based materials to resist salt attack.