Experimental Study On Chloride Penetration Resistance Of Hybrid Fiber Reinforced Recycled Brick Aggregate Concrete

In order to solve the shortage of natural aggregate,recycled brick aggregate concrete(RBAC)appears in people's vision.But many studies showed that the durability and the basic mechanical properties of RBAC,were lower than that of common concrete.Thus,hybrid fibers were added into RBAC to improve the performance of RBAC,and to expand the range of application.In this study,a method of adding hybrid fiber into recycled brick aggregate concrete had been put forward,the water-cement ratio,replacement ratio of recycled brick aggregate and fiber volume content were taken as experimental parameters,and carried out the compressive strength tests,splitting tensile strength tests and chloride ion corrosion resistance of hybrid fiber recycled aggregate concrete(HFRBAC).Then,the main contents are as follows:1.A total of 60 cube specimens with the size of 150mm?150mm?150mm were tested to investigate the effects of varying parameters on their compressive strength and splitting tensile strength.Then the relationship of tension-compression ratio of HFRBAC with the characteristic parameters of fiber content was bridged.The results showed that the compressive strength and the splitting tensile strength decreased obviously with the increasing of water-cement ratio and replacement radio of recycled brick aggregate.However,with the fiber volume content increased,the compressive strength and the tensile strength increased gradually.2.The anti-chloride ion penetration of 30 prism specimens with the size of 100mm?100mm?200mm subjected to drying-wetting cycles were tested.Then,the water soluble chloride ion contents at different sample depths were measured by using the method of chemical titration.Results indicated that the water soluble chloride ion content of HFRBAC increased with the increase of water-cement ratio and recycled brick aggregate replacement ratio.However,with the increasing of hybrid fiber addition,the water soluble chloride ion contents increased gradually in concrete surface,but decreased in the interior of specimens.3.Based on the results of water soluble chloride ion contents at different sample depths,the surface chloride ion concentration and chloride ion diffusion coefficient were calculated according to Fick's second law by using Matlab.Then,the influences of the water-cement ratio,recycled brick aggregate replacement ratio and fiber content on surface chloride ion concentration and chloride ion diffusion coefficient were studied.At last,the relationship between varying parameters and surface chloride ion contents was proposed.Also,the expressions and recommended values of the influence of varying parameters on the chloride ion diffusion coefficient were obtained.