Experimental Research On Sulfate Corrosion Resistance Of Concrete Under Dry And Wet Environment

Sulfate corrosion is an important factor leading to damage and destruction of concrete structure,especially in the Western Salt Lake and saline soil,which are sulfate corrosion environment,the damage of durability of concrete is more serious.Especially under the action of dry-wet cycle,the superposition of the two corrosion effects aggravates the damage of durability of concrete.Therefore,the study of concrete durability in Western Salt Lake area should be paid enough attention.How to prevent and mitigate the corrosion damage of concrete materials caused by sulfate dry-wet cycle has become an important content of concrete durability research.Therefore,the accelerated test of sulfate drying-wetting cycle is carried out in the laboratory,and the macro and micro performance of concrete is selected.The characteristics of concrete damaged by sulfate drying-wetting cycle are studied.The specimens with different water-binder ratios and mix ratios are designed and immersed in the solution for dry-wetting cycle corrosion.In this paper,the variation of macroscopic properties such as compressive strength,flexural strength,mass and dynamic elastic modulus of specimens with the number of dry-wet cycles is analyzed.The Micro-properties of porous structures such as gas content,average chord length of bubbles and pore spacing coefficient are studied,and the variation of electric flux of reactive impermeability is also studied.The main conclusions are as follows:1.The changing trend of macroscopic properties such as compressive strength,flexural strength,mass and dynamic elastic modulus of concrete after wet-dry sulfate cyclic corrosion is basically the same.2.The addition of mineral admixtures can effectively improve the resistance of concrete to sulfate dry-wet cyclic corrosion,among which fly ash has the best effect on improving the macroscopic performance of concrete subjected to sulfate dry-wet cyclic corrosion.3.Although the addition of mineral powder can improve the resistance of concrete to sulfate dry-wet cyclic corrosion to a certain extent,it has a great adverse effect on the improvement of initial strength of concrete.The amount of mineral powder should be controlled within 30% in engineering.4.Mineral powder can effectively improve the micro-pore structure and impermeability of concrete.Fly ash has a slightly poor effect.Without mineral admixtures,pore structure and impermeability deteriorate fastest.5.The variation of pore structure parameters before and after corrosion is linearly correlated with strength,quality and impermeability.