| When reinforced concrete buildings are subjected to chloride ion attack,the internal reinforcement will rust and corrosion products will cause the concrete to expand in volume,leading to cracks in the concrete,which in turn will cause instability damage to the overall reinforced concrete structure.How to improve the chloride ion corrosion resistance of concrete is a common concern of many researchers and scholars at home and abroad.New building materials can not only improve the basic performance of concrete,but also alleviate the problem of resource scarcity to a certain extent.The addition of ceramic powders and calcium sulphate whiskers can improve the strength and chloride resistance of concrete,and also provide a theoretical basis for the study and use of solid waste minerals and fibre materials in concrete.It is therefore important to investigate the effect of the type and amount of admixture added on the mechanical properties and resistance to chloride ion attack of concrete.The main elements of the study are as follows:(1)The durability of reinforced concrete structures in a chloride ion environment is described;the test proportions of concrete are calculated and the resistance to chloride ion attack of concrete with admixtures is investigated based on the rapid chloride ion migration method and the galvanic corrosion method.(2)The effect of mixing ceramic powder and calcium sulphate whiskers on the compressive strength,flexural strength and brittleness of concrete at different ages was analysed by testing the mechanical properties of concrete.The results show that the ceramic powder alone decreases the compressive strength of concrete,while the addition of a certain amount of calcium sulphate whisker increases the compressive strength of concrete at the same age,and the calcium sulphate whisker also increases the flexural strength of concrete,and the effect is greater in the early stage.The brittleness of the concrete is significantly improved by the ceramic powder in the later stage,and the brittleness of the concrete is adversely affected by the calcium sulphate whisker,while the brittleness of the concrete is effectively improved by the combination of ceramic powder and whisker in the early stage.(3)The chloride ion diffusion resistance of concrete mixed with ceramic powder and calcium sulphate whisker was analysed by the rapid chloride ion migration test.It is concluded that the best chloride ion diffusion resistance of concrete is achieved at 20%of ceramic powder;the addition of calcium sulphate whiskers can effectively improve the chloride ion diffusion resistance of concrete;the compounding of ceramic powder and calcium sulphate whiskers also improves the chloride ion erosion resistance of concrete within a certain dosing range.The test equipment was used to test the resistance to chloride ion attack of reinforced concrete specimens,and the changes in the overall electrical conductivity of the specimens led to the conclusion that the protection performance of concrete against reinforcement corresponds to its resistance to chloride ion attack.(4)The multi-physics field numerical analysis software COMSOL was used to simulate the chloride ion diffusion process in the load-bearing part of the cantilevered retaining wall under the combined effect of load and chloride salt.The results show that the chloride ion erosion concentration inside the concrete tends to stabilise for external loads at 0.6 times lateral earth pressure and 0.9 times lateral earth pressure,and that the internal structure hinders the diffusion of chloride ions to some extent under 0.9 times lateral earth pressure. |
