Research on the Prediction of Mechanical Response to Concrete under Sulfate Corrosion Based on the Grey Theory

In order to predict the influence on mechanical properties of concrete under sulfate erosion, based on the experimental data and Grey Theory, GM (1,1) model is used to establish models C20, C40, C60, C80 to predict concrete crushing strength in the natural drying process under an erosion of 6.9% concentration sodium sulfate, and correlation is calculated between concrete strength grade, splitting tensile strength and compressive strength. The calculation analysis shows that (1) for low strength concrete (C20), most strength loss occurs in the initial stage of deterioration, and over time the deterioration rate gradually decreases and then increases again until being damaged; (2) in the wet-dry cycles, at the same strength level, the splitting tensile strength loss is more significant than the compressive strength loss; (3) with the increase of concrete grade, the sulphate resistance capability of concrete is reinforced. Compared with C20, the compressive strength loss of C80 is reduced to 27.4% and 30% respectively in 360 and 720 times of wet-dry cycles. The anti-erosion capacity of concretes has been greatly enhanced; (4) the deterioration of high-strength concrete is very slow in the later stage. The compressive strength loss of C80 decreases by 2% in every 90 times of wet-dry cycles and decreases to 27% in 1600 times of wet-dry cycles.