Shear Behavior Of Recycled Brick Aggregate Hybrid Fiber Concrete

An experimental research on the compressive properties and shear performance of recycled brick aggregate hybrid fiber reinforced concrete was performed in this paper, and influences of the water-cement ratio, recycled brick aggregate replacement ratio and the volume fraction for hybrid fiber on the cube compressive strength, shear strength and shear ductility were analyzed. The main contents are as follows:1.Through the cube compressive test on 30 specimens in size of 150 mm 150mm 150 mm and the direct double shear test on 40 specimens in size of 100 mm 100mm 400 mm, the influences of the water-cement ratio, recycled brick aggregate replacement ratio and the volume fraction for hybrid fiber on the cube compressive strength and shear strength are analyzed. Results indicate that cube compressive strength and shear strength decrease obviously with the increase of the water-cement ratio. With the increase of recycled brick aggregate, the cube compressive strength and the shear strength decrease. When the substitution rate is 100%, the compressive strength decreases greatly, to be about 36.7%; the maximum reduction of the shear strength is about 39.0%, when the substitution rate is 50%.The addition of hybrid fibers has a certain improvement on the cube compressive strength, and more obvious for the shear strength. When the volume fraction of the hybrid fibers is 1.5%, the shear strength increases about 111%.2. According to the measured shear-shear slip curves of recycled brick aggregate hybrid fiber reinforced concrete, a method is proposed to calculate the nominal average equivalent shear strength and shear ductility index by analyzing the post-peak load drop rule and using the basic principle of integral. Results indicate that the shear ductility of recycled brick aggregate hybrid fiber reinforced concrete get better when the water cement ratio is 0.33 and 0.38; The addition of recycled brick aggregate improves the shear ductility of Hybrid Fiber Reinforced Concrete, and when the substitution rate is 50%, the ductility is best; The addition of hybrid fibers can obviously improve the shear ductility of Recycled Brick Aggregate Concrete, and when the volume ratio of fiber is 1%, the ductility is best.3. The relationship of shear strength and fiber content characteristic parameter of recycled brick aggregate hybrid fiber reinforced concrete is proposed.