Study On The Double Erosion Performance Of High Sulfate Resistant Cement Concrete And Magnesium Salt

Aiming at the double erosion damage problem of sulfate and magnesium salt that the concrete structure faces in some areas of Xinjiang, in order to investigate the anti erosion performance of high sulfur cement concrete under double erosion conditions, we put high sulfate resistant cement with different C₃S content, different water cement?adhesive? ratio and high sulfur resistant cement mortar with different fly ash content into the double erosion solution of sulfate and magnesium salt with different concentrations to make erosion experiments, to study the ability of double erosion that high sulfur resistant cement concrete resists sulfate and magnesium salt, and the effect that water cement ratio, fly ash content and other factors have on the high performance of high sulfur cement concrete resisting double erosion. Through the experimental analysis to find:?1? High sulfate resistant cement concrete only resists the double erosion of sulfate and magnesium salt with lower concentrations concentration(SO42-?4000 mg/L,Mg²⁺?1000 mg/L).?2?The water cement ratio has a certain effect on the ability that high sulfur cement concrete resists the double erosion of sulfate and magnesium salt. Under the double erosion condition of sulfate and magnesium salt with lower concentration, reducing the water cement ratio has an obvious effect on enhancing the ability that high sulfur resistant cement mortar resists the double erosion of sulfate and magnesium salt, but under the double erosion of sulfate and magnesium salt with high concentration( SO42-?8000 mg/L, Mg²⁺?3000 mg/L), even if the water cement ratio is reduced, the high sulfur resistant cement mortar is still difficult to resist the double erosion damage effect of sulfate and magnesium salt.?3? The content of fly ash has a certain effect on the performance high sulfur cement concrete resists the double erosion of sulfate and magnesium salt. Adopt rubber sand specimen which is made of high sulfate resistant cement with low content of C₃S, taking the water cement ratio which is 0.4 and the content of fly ash is respectively 0%, 15%, 25% and 35%, in the double erosion environment of lower concentrations(SO42-?8000, Mg²⁺?1000), increase the fly ash volume, which is beneficial to improve the ability that high sulfur resistant cement mortar resists erosion; but in the double erosion environment of higher concentrations( SO42-?8000, Mg²⁺?3000), increase the volume of fly ash, which cannot improve the ability that high sulfur resistant cement mortar resists erosion.?4?The content of C₃S in high sulfur resistant cement has some effect on the ability that high sulfur cement concrete resists the double erosion of sulfate and magnesium salt. Compared with the erosion testresults that two kinds of rubber sand specimen made of high sulfur resistant cement whose C₃S content are35.66% ? 46.37% respectively are in the double erosion solution of sulfate and magnesium salt with different concentrations, it is found that the corrosion resistance coefficient of the rubber sand specimen with high content of C₃S is obviously less than the rubber sand specimen with low content of C₃S. It shows that the higher the content of C₃S in the cement is, the more calcium hydroxide generated is, eroded gypsum and magnesium hydroxide will increase with them, and the easier it is to suffer the double erosion erosion of sulfate and magnesium salt damage.?5?By scanning electron microscope?SEM? and energy spectrum analysis?EDS? to conduct microscopic observation about the test specimen suffering the double erosion,it is found that: The main types of high sulfate resistant cement mortar suffering the double erosion erosion of sulfate and magnesium salt damage are the surface damage of crystalline magnesium hydroxide, the extent of erosion damage is whether the thickness of the surface layer of the specimen is large or small, the larger the thickness of the erosion layer is, the smaller the corrosion resistance coefficient of test specimens is, the more serious the extent of the erosion damage is. Moreover, apart from magnesium hydroxide and magnesium silicate hydrate generation inside the test specimen with a high content of three calcium silicate, it is also found the destruction of gypsum and Ettringite crystallization.