Experimental Study On Mechanical Properties Of Basalt-polypropylene Hybrid Fiber Reactive Powder Concrete

Reactive Powder Concrete(RPC)is a new type of high-performance composite material with high mechanical properties and excellent durability.The incorporation of steel fiber in RPC greatly improves the ductility of concrete,so it has a lot of application prospects in many engineering fields of RPC.However,steel fibers will be corroded in a serious corrosion environment.This will lead to further corrosion of the internal reinforcement.The service life and bearing capacity of the structure are seriously affected.Therefore,it is necessary to find other kinds of high performance fiber instead of steel fiber.In recent years,basalt and polypropylene fiber RPC as a new material gradually appear in the field of vision.Its appearance has improved the toughening and cracking resistance of RPC.At present,there are few studies on the basalt and polypropylene hybrid fiber RPC,especially for its constitutive relationship.Therefore,the basic mechanical properties and constitutive relation of basalt-polypropylene hybrid fiber RPC were studied in this paper.The main research work and achievements are as follows:(1)Based on the influence of fiber content and mixing mode,cubic compressive strength test,splitting tensile strength test and flexural strength test of single-mixed and mixed basalt fiber and polypropylene fiber RPC specimens were carried out.The results show that the compressive strength,splitting tensile strength and flexural strength of RPC can be enhanced by single and mixed basalt and polypropylene fibers.Basalt and polypropylene fibers have not significant effect on improving compressive strength of RPC,but they have significant effect on improving splitting tensile strength and flexural strength of RPC.When the content of basalt fiber is 0.15% and the content of polypropylene fiber is 0.033%,the strengthening influence is the most obvious,which is 14.1% higher than that without fiber RPC;When the content of basalt fiber is 0.15% and the content of polypropylene fiber is 0.025%,the strengthening influence is the most obvious,which is 52.1% and 26.14% higher than that without fiber RPC respectively.At the same time,the hybrid effect analysis of the effect of hybrid fibers was conducted,and the best hybrid method was obtained.(2)The axial compression tests of 9 groups hybrid fiber RPC prisms are finished,and the compression stress-strain curves of hybrid fiber RPC specimens were obtained.Based on the measured stress-strain curves,the constitutive equations of axial compression of hybrid fiber RPC were established by analyzing and fitting.At the same time,the axial compressive strength,peak strain,Poisson's ratio,elastic modulus and other parameters of each group were analyzed,and the impact of the hybrid fiber on the parameters was obtained.(3)The axial tension tests of 6 groups hybrid fiber RPC prisms are finished,and the tension stress-strain curves of hybrid fiber RPC specimens were obtained.Based on the measured stress-strain curves,the constitutive equations of axial tension of hybrid fiber RPC were established by analyzing and fitting.The effects of hybrid fiber on tensile strength,modulus of elasticity and fracture position are emphatically analyzed.The correlation of splitting tensile strength,flexural strength and axial tensile strength was determined.