Research On Damage Mechanics Properties Of Hybrid Polypropylene Fiber Concrete

Fiber concrete is a new composite building material that develops very fast inrecent years, and is widely used civil engineering, construction, transportation, waterconservancy and other fields. Adding fiber in the concrete can improve the inherentdefects of concrete from the material composition, effectively improve the concrete’scracking resistance, toughness, permeability resistance, improve the performance ofconcrete’s strength, durability and abrasion resistance. The hybrid fiber concrete is anew direction of development for the fiber concrete, it has the step by step crackingresistance and performance complementation in different structural levels and loadgrades, it has a better improvement and enhancement comparing with the single fiber,but the research of hybrid fiber concrete is relatively less at present. This article usestheoretical analysis, laboratory test and numerical simulation, and so on, takes arelatively systematic and deep analysis to the damage mechanical properties of hybridand single polypropylene fiber concrete. The main research work and achievements areas follows:①Carry on the hybrid polypropylene fiber concrete axial compressive and tensileexperiment, and research on the hybrid polypropylene fiber and single polypropylenefiber improvement effect to the concrete about the strength and toughness. The resultshows that most single polypropylene can slightly enhance the concrete’s compressivestrength and elasticity modulus and all single polypropylene can enhance the concrete’stensile strength in some extent. While the hybrid polypropylene can enhance both thecompressive strength and tensile strength, and the enhancement effect is obviouslybetter than the former. The concrete mix with polypropylene fiber has a better curveductility in the compressive and tensile curve’s trend, and the hybrid polypropylenefiber’s curve ductility is clearly better than the single polypropylene fiber’s. This resultshows that the hybrid polypropylene fiber has a significantly better improvement in theconcrete’s strength and toughness effect than the single polypropylene fiber.②Combining finite element analysis software ABAQUS with fiber concretedamage constitutive model to carry on the numerical simulation of the experimentalmodel with the same conditions, and comparative analysis the numerical simulationresults and experimental results that verify the correctness of numerical simulation. Thenumerical simulation result gets the changing law of curve shape parameters of polypropylene fiber concrete the damage constitutive model’s damage factor and theconcrete compression, tension damage factor’s development law with strain.③Using the ABAQUS finite element software to analyze the damage mechanicalproperties of fiber concrete with different concrete strength grade. The results show thatwithin a certain range of concrete strength grade, the concrete cumulative damageincreases with the reduction of the concrete strength grade, but the cumulative damagedifference is very small between the different concrete strength grade.