Experimental Research On Erosion Of Recycled Concrete With Iron Tailing Sand As Fine Aggregate In Salt Spray Evironment

China’s urbanization process has developed rapidly in recent years,bringing unprecedented development opportunities to the construction industry and steel industry.But at the same time,a large number of abandoned concrete and iron tailings are produced,occupying land and polluting resources,which bring great challenges to the earth’s ecological environment.The recycled aggregate obtained from the broken waste concrete has low strength and poor durability,and its application is greatly restricted.At present,it is only used in non-structural concrete such as roadbed and backfill.At present,the research on the performance improvement of recycled concrete has been paid much attention by scholars at home and abroad.Chlorine erosion is one of the important factors affecting the durability of concrete.Relevant studies can make recycled concrete meet the construction requirements of structural buildings near the sea.Therefore,it is of great significance in theory and practice to study the improvement of chlorine erosion resistance of recycled concrete by iron tailings.Through neutral salt spray corrosion test,the influences of iron tailings content and salt spray corrosion time on ultrasonic velocity,chloride ion erosion depth,quality and tensile strength of recycled concrete were studied.The results show that the internal compactness,tensile strength and chloride penetration resistance of recycled concrete are relatively the best when the content of iron tailings is 20%.At the early stage of salt spray erosion(14d),the invasion of chlorine ions can enhance the internal structure density of recycled concrete and improve its durability and mechanical properties.The microstructure of recycled concrete from iron tailing ore was obtained by SEM scanning experiment,and the relationship between the migration of chloride ion and the microstructure of recycled concrete was established.At the microscopic mechanics level,based on the secondary development technology of ABAQUS,a two-dimensional random aggregate numerical model of the regenerated concrete test block of iron tailings was established by writing Python script.Using ABAQUS mass diffusion module(mass difusion)respectively to simulate the chloride ions at the end of 20% iron ore content of recycled concrete and ordinary concrete block,block the diffusion law,and the simulation results compared with the test results is analyzed,and the results show that the simulated results and experimental results on the rule change is consistent,the mesoscopic mechanics level,using ABAQUS to simulate the chloride ion diffusion behavior is completely feasible.