Study On Durability Of Rubber Concrete Under Freeze-thaw Cycle And Chloride Ion Erosion

The durability of concrete structures is one of the hot topics in the engineering field.With the application of concrete structure in the engineering under the complicated environment such as hydraulic engineering,bridge,road and so on,Durability failure mechanism of concrete becomes more complicated.Freeze-thaw,chloride ion erosion,alkali aggregate reaction,carbonation and other alternating effects accelerate the deterioration of concrete performance,seriously affecting the safety and use of engineering structures.The maintenance cost of durability failure is often about 5 ~ 20 times of the initial construction cost.Therefore,it is of great scientific significance and practical value to study the durability of concrete under the action of multi-factor coupling.In this paper,rubber concrete specimens were prepared by replacing the fine aggregate in raw materials with rubber particles of 5 ~ 8 mesh,30 ~ 40 mesh and 60 ~80 mesh in the same volume according to the ratios of 5%,10% and 15%,respectively.The action mechanism of rubber concrete under different coupling conditions of freeze-thaw cycle and chloride ion erosion is deeply explored,that is,the simultaneous action of freeze-thaw cycle and chloride ion erosion,and the superposition of freeze-thaw cycle and chloride ion penetration resistance.The relationship between frost resistance of rubber concrete and particle size and content of rubber concrete was studied by analyzing the experimental data,The results show that rubber particles can significantly improve the frost resistance,salt frost resistance and chloride permeation resistance of concrete.The smaller the particle size of rubber particles,the better the effect.The optimal rubber content of frost resistance and salt frost resistance of concrete is 10%.The chloride permeability of rubber concrete decreases with the increase of freeze-thaw cycles,and the optimum rubber content to improve chloride permeability ofconcrete is 10%.Therefore,considering the salt freezing resistance and chloride ion permeation resistance of rubber concrete,the optimum content of rubber particles should be 10%.Based on the Fick diffusion law and the service condition of rubber concrete in actual environment,the chloride ion diffusion model of rubber concrete is established,which is helpful to describe the chloride ion diffusion performance of concrete completely and accurately.The theoretical damage model of rubber concrete under the coupling action of freeze-thaw cycle and chloride ion erosion was established by means of experimental study,and the actual safe service life of rubber concrete was preliminarily predicted according to the damage model.