Research On The Mechanical Of Sulphate And Chloride Attack To Cement Base Material

China has a long coastline and large number of salt inland lakes, reinforced concrete in these areas is often subjected to the combined effect of sulfate and chloride salt and other corrosive ions. Sulfate attack is the most harmful factors to concrete itself in the environment, and chloride salt corrosion destroy sthength of rebar in concrete, and thus affect the strength of the concrete. By choosing different cement base material, this paper designed the corrosion of a single sulfate, the corrosion of recombination action and the corrosion of sulphate and chloride salt in turn. Using the method of full immersion the regular basis of mechanical properties, inflation rate, and the corrosion depth of two kinds ions is studied.(1) Based on the full immersion environment, Portland cement mortar block and high sulfate resistant cement mortar block are soaked in 5% sodium sulfate solution and 5% sodium sulfate + 5% sodium chloride solution. The flexural and compressive strength of high sulfate resistant cement is higher than that of ordinary Portland cement, but also showed good resistance to sulfate.; each relative dynamic elastic modulus is gradually increased with the age, the highest increase rate is about 20% within the test age, And for the same kind of cement in different conditions, the relative dynamic elastic modulus has the same trend; expansion ratio of test block is that the early stage of the block rate is faster,and the late stage changes slowly. The expansion rate of high sulfate resistant cement is higher than that of ordinary Portland cement, and average length is more than 0.01%; two kinds of ions, sulfate ion and chloride ion in solution interact each other in order to make transmission speed of two kinds ions to become slow, and the higher is water cement ratio, transmission speed is faster; At last, by thermogravimetric analysis(TGA), it is concluded that in the two kinds of erosion environment the most important reason of increased strength of block is that gypsum content increased.(2) Based on the full immersion environment, mortar block soaked 28 days in 5% sodium sulfate solution and then soaked 90 days into the 5% sodium chloride solution(experimental group) to research on the effects of two kinds of cement mortar, and established the control group, after soaked in the water 28 days, mortar block soaked 90 days into 5% sodium chloride solution. The results showed as follows that the strength of experimental group grow faster than the control group in sodium sulfate solution, and the strength is relatively high, so there is reason to increase strength in the short term; The relative dynamic modulus of the experimental group showed a trend of growth before the 90 days, after it keep the basic stability, while the relative dynamic modulus of the control group showed a trend of growth before the 60 days.; the expansion rate of the test block has a general rule that the early stage of the block rate is faster,and the late stage keep steady, the growth rate of experimental group was obviously higher than that of control group; the free sulphate ions of high sulfate resistant cement in sodium chloride solution is easy to loss, and the reaction of sulfate ions in ordinary Portland cement is more; in terms of the chloride ion erosion, experimental group after soaked in sodium sulfate solution, transmission speed of the chloride ion increases, and high sulfate resistant cement is less susceptible to the chloride ion erosion.