Study On Chloride Ion Permeability And Service Life Prediction Of Crumb Rubber Concrete

Crumb Rubber Concrete(CRC), is made by replacing a portion of aggregates with shredded worn-out automobile tire particles or chips in Portland cement concrete. CRC is known as a new concrete material, characterized by low Young's modulus, large deformation, high energy dissipation and extremely good crack resistance.Several problems of the durability of the roadway and bridge concrete have been become crucial in cold, marine and brackish environment because of chloride ion penetration. The performance of CRC to resist chloride ion penetration should be relation to its application in civil engineering. Therefore, the chloride ion permeability of CRC is studied in the paper.We use ASTM C1202-97 rapid testing method of chloride permeability to testify the CRC. Test results show that the addition of crumb rubber aggregate in concrete can improve the chloride ion permeability of concrete to some extent. The improving effect of rubber particles(1mm~2mm) is better than that of rubber chips(4mm~6mm). Adding mineral functional material in CRC can enhance its anti-chloride permeability. CRC with amount of crumb rubber to 100kg/m3 in volume have nicer durability and meet the need of common construction, because its compressive strength can reach C30, the charge passed through it is typically in the order of 1000C, and is considered very low according to ASTM C1202-97 standard.The service life of CRC in chloride ion environment has been studied. On the basis of the theory of reinforcement corrosion caused by chloride and reference to published literatures, a chloride diffusion model considering the chloride binding capacity, time-dependent quantities of diffusion coefficient and micro-defects of concrete is presented in this paper, at the same time, the determination of model factors are analyzed. The service life of CRC and ordinary Portland concrete(OPC) in marine environment and deicing salt zone is evaluated theoretically by adopting this chloride diffusion model in concrete. Results show that the service life of CRC is greatly longer than that of OPC. Furthermore, the durability design way is put forward, and durability design of CRC has been experimented for the first time in the paper.