Study On Constitutive Model Of Steel-PVA Hybrid Fiber Cementitious Composites

Fiber reinforced cement matrix composites have been efficiently used in the engineering field with superior performance,but the single fiber cement based composite materials are still in the performance limitations,which limits its application in the engineering,so more than two kinds of hybrid fiber reinforced hybrid composites of cement matrix have been developed.Hybrid fiber composites greatly expand the properties and range of application of composites.The purpose of mixing is to complement each other to achieve synergistic optimization effect on fracture toughness,impact resistance and fatigue resistance of cement-based composites.And fiber hybrid can also effectively reduce the cost of composite materials.In this paper,the influence of steel fiber and PVA fiber mixed with cement-based materials on mechanical properties and the establishment of constitutive model of hybrid fiber reinforced cement-based composites are studied.Two mixing ratios were designed and the water binder ratio was 0.45 and 0.38,respectively.12 groups of different fiber contents were set under each mix ratio to prepare the hybrid fiber cement matrix composite specimens.The test data are obtained by means of cube compression,cylinder splitting tensile and cylindrical axial compression test.Test results show that the hybrid fiber can effectively improve the mechanical properties of cement based composite materials,improve the compressive strength of cement based composite materials,splitting tensile strength,enhanced toughness of cement-based composite materials.Based on the experimental data,the relationship between the volume fraction of steel fiber and the volume fraction of PVA and the compressive strength and splitting tensile strength of hybrid fiber reinforced cement based composite cube was established.In addition,the uniaxial compressive stress-strain curves are analyzed,comparison of hybrid fiber reinforced cementitious composites,cement based composite and single fiber cement based composite material stress-strain curve,we can see that the hybrid fiber reinforced cementitious composites stress-strain curve decline shows better ductility.According to the obtained experimental stress-strain curves,establishes axial compressive strength,steel fiber volume ratio,PVA cylinder volume ratio and uniaxial compressive peak relationship between stress and peak strain,referring to the non linear elastic theory of concrete uniaxial compression constitutive model,fitting the stress-strain curve obtained ascent and the decline in the formula A,B two parameters,given the compressive strength and the fiber volume fraction of hybrid fiber reinforced cementitious composites under uniaxial compression based on stress strain constitutive model.