Experimental Study On Static Properties And Impact Resistance Of Steel PVA Fiber RPC

Reactive Powder Concrete（RPC）is a high-performance concrete with high strength and durability,and thus has a wide application prospect due to its excellent performance.However,due to the high cost of steel fibers in RPC,so in order to accelerate its promotion,and to solve the economic and limitations brought about by a single fiber,different types,lengths and shapes of fibers can be mixed into RPC to prepare a lower cost and higher performance mixed RPC.in recent years,polyvinyl alcohol fiber（referred to as PVA fiber）as a new material gradually appear in the construction project,its low cost It has low cost and high tensile strength,which can improve the tensile deformation resistance and toughness of concrete.In this thesis,6 mm PVA fiber and 12 mm PVA fiber are chosen to be mixed with steel fiber to prepare hybrid RPC,to study its static properties and observe the microstructure,and to study its impact resistance under impact load.The main contents of this thesis are as follows:（1）A single-factor static performance test study of single-doped steel fiber RPC and hybrid RPC（6mm PVA fiber and 12mm PVA fiber blended with steel fiber,respectively）was conducted to investigate the effect of hybrid fiber on the strength of RPC matrix and the optimal volume doping for fiber blending,and electron scanning microscopy（SEM）was used to investigate the hybrid The internal pores of the RPC matrix and the excessive interface morphology between the fibers and the matrix were observed and analyzed by SEM.（2）A drop hammer impact tester was used to test the impact resistance of single-doped steel fiber RPC and hybrid RPC,and the damage patterns of the specimens were observed and analyzed,and the number of initial crack impact N₁ and final crack impact N₂ were recorded,and the test indices such as initial crack impact energy W₁,final crack impact energy W₂,ductility ratio B,and post-crack energy（35）W were analyzed to investigate the relationship between single-doped steel fiber,6mm PVA fiber and 12mm PVA fiber,respectively.The impact resistance of RPC is investigated when steel fiber,6mm PVA fiber and 12mm PVA fiber are blended with steel fiber,and the optimal amount of fiber blending.The test results prove that the fiber blending can improve the impact resistance of RPC.（3）Based on the impact test,the Weibull distribution function theory was introduced,and the applicability of the two-parameter Weibull distribution function was verified by fitting the data to the impact times of the single-doped steel fiber RPC and the blended RPC based on the results of the drop hammer impact test,and the estimated life time of the impact resistance of each group of RPC under different failure probabilities was calculated.（4）Based on the damage theory of Weibull distribution function,the damage evolution equations of single-doped steel fiber RPC and hybrid RPC under impact loading were established respectively,and the corresponding damage evolution diagrams were drawn to compare and analyze the service life of RPC under different damage variables D.