Study On Sulfate Corrosion Resistance Of Concrete With Fly Ash And Slag

Concrete is a widely used building material.In engineering practice,it is found that sulfate corrosion is the main reason to reduce the durability of concrete.Mineral admixture is one of the important factors in the process of concrete sulfate corrosion.Traditional research is only to design the mix ratio by changing the mixing ratio and method of different mineral admixtures,and use the later verification test to obtain the optimal plan.Because the fineness of mineral admixtures is closely related to the compactness of concrete,it is of great engineering significance to study the durability of concrete by combining the fineness of mineral admixtures with other influencing factors.In this paper,the slag and fly ash with different finenesses are tested for double mixing.according to the results of the pure slurry fluidity test,a mix ratio with good filling properties is selected,and the durability of the four cementing material particle matching methods is verified through the later dry-wet cycle sulfate corrosion test.Based on the best particle matching method of the cementitious material,design the water-binder ratio,the total amount of mineral admixtures,and the curing age three sets of variables,using the concrete appearance,mass change rate,relative dynamic elastic modulus and relative flexural strength Such evaluation indicators represent the degradation law of concrete with the increase of erosion age,and the gray correlation analysis method is used to explore the degree of influence of various factors on concrete.Combined with SEM,EDS energy spectrum analysis,and XRD microscopic technology,it reveals the sulfate corrosion damage mechanism of double-mixed slag and fly ash concrete with different mix ratios.The main conclusions are as follows:The results show that the fluidity test can achieve the optimal design of cementitious materials,and obtain the matching mode of cementitious material particles with excellent sulfate corrosion resistance.The double mixing mode of grade I fly ash and S95 slag is the best.The internal pores are filled by making full use of the effect of particle gradation and morphology,and the self compactness is improved.The matching mode of cementitious material particles for the double mixing slag fly ash concrete is sulfate corrosion resistant The correlation degree between the four factors and sulfate corrosion resistance of double slag fly ash concrete from high to low is as follows: water binder ratio > mineral admixture content > cementitious material particle matching > curing age.With the decrease of water binder ratio,the internal microstructure of concrete becomes denser and the sulfate corrosion resistance improves.With the increase of the total amount of mineral admixture,the sulfate corrosion resistance of concrete is enhanced,but the total compressive strength of the experimental group with 80% of the total amount of mineral admixture is low,and the total amount of mineral admixture should not be too high.With the increase of curing time,the hydration reaction of cementitious materials is more thorough,the porosity of concrete is obviously reduced and the sulfate corrosion resistance is improved.Based on the matching of the gelled material particles,the research on sulfate corrosion resistance of double slag fly ash concrete provides a certain theoretical reference and technical support for the durability design of mineral admixture concrete in the future,and reduces the blindness of mix proportion design.