Experimental Study On Basic Mechanical Properties Of Waste PP Fiber Reinforced Recycled Aggregate Concrete

Waste PP fiber reinforced recycled aggregate concrete（WPF-RAC）refers to made waste polypropylene products into fibers as reinforced and toughened materials of recycled aggregate concrete,cast by the construction technology of fiber reinforced concrete.In this thesis,11groups of WPF-RAC test blocks were made by using waste PP fibers in different lengths made of waste PP bands as reinforcement and mixed with recycled aggregate concrete with different volume content of fiber and different replacement rate of recycled aggregate,and the basic mechanical properties were studied.The main research contents and results are following:（1）The effects of volume content,length-diameter ratio of waste PP fiber and replacement rate of recycled aggregate on cube compressive strength and splitting tensile strength of WPF-RAC were studied by cube compressive test and splitting tensile test.It was found that the cube compressive strength and splitting tensile strength increase firstly and then decrease with the increase of volume content,length-diameter ratio of fiber,and decrease with the increase of replacement rate of recycled aggregate.The conversion formula of cube compressive strength and splitting tensile strength was proposed by fitting the data.（2）The axial compressive strength,the static elastic modulus,axial compressive stress-strain curves,peak strain and equivalent compressive toughness index were obtained by axial compressive test to study the influence of the volume content,length-diameter ratio of waste PP fiber and replacement rate of recycled aggregate in axial compressive performance of WPF-RAC.It was found that the axial compressive strength increase firstly and then decrease with the increase of volume content and length-diameter ratio of fiber,and decrease with the increase of replacement rate of recycled aggregate,which is similar to the effect of each parameter on the cube compressive strength.The static elastic modulus decrease with the increase of volume content,length-diameter ratio of fiber and replacement rate of recycled aggregate.The equivalent compressive toughness indexes W_cu^1.0,W_cu^0.8 and W_cu^0.4 increase firstly and then decrease with the increase of volume content and length-diameter ratio of fiber.W_cu^1.0 increase with the increase of replacement rate of recycled aggregate but the amplitude was not obvious.W_cu^0.8 and W_cu^0.4 decrease firstly and then increase with the increase of replacement rate of recycled aggregate.The constitutive formula of WPF-RAC was proposed by fitting the measured stress-strain curves.（3）The tensile stress-strain curves ascent segment,axial tensile strength,peak strain initial cracking strength and equivalent tensile toughness index were obtained by the axial tensile test to study the influence of the volume content and length-diameter ratio of waste PP fiber and replacement rate of recycled aggregate on axial tensile performance of WPF-RAC.It was found that the axial tensile strength increase firstly and then decrease with the increase of volume content and length-diameter ratio of fiber,and decrease with the increase of replacement rate of recycled aggregate.The initial cracking strength increase firstly and then decrease with the increase of volume content of fiber,and decrease with the increase of length-diameter ratio of fiber and replacement rate of recycled aggregate.The peak tensile strain increase firstly and then decrease with the increase of volume content and length-diameter ratio of fiber,and increase with the increase of replacement rate of recycled aggregate.The initial cracking strain increase firstly and then decrease with the increase of volume content and length-diameter ratio of fiber,and decrease with the increase of replacement rate of recycled aggregate.