Study On Dynamic Mechanical Properties Of Fiber Polymer Cement Mortar

Cement-based materials have been widely used in civil engineering,although their low tensile strength,easy cracking and brittleness limit their development deeply.Researches show that the polymer modified cement-based material can improve the compactness,cohesiveness,durability and elongation of the matrix,and the fiber-reinforced cement-based material can improve the strength,toughness and impact resistance of the matrix.But little research about the mechanics of a cement-based material mixed with polymer and fiber has been found,especially for its dynamic mechanical property.In this paper,four water-based epoxy resin modified cement-based materials with different poly-ash ratios?2%,4%,6%,8%?were prepared by post-mixing method,and four different dosages?0.2%,0.3%,0.4%,0.5%?aramid fiber reinforced cement-based material test specimens and cement-based material test specimens with aramid fiber and waterborne epoxy resin.Their static and dynamic mechanical properties were studied systematically and respectively.The scanning microscope technique was used to scan the microstructure of test specimens after dynamic splitting and tensile failure to research the microcosmic mechanism effect.The mechanism of the mechanical properties of the composite fiber and polymer cement mortar was also analyzed by LS-DYNA finite element software for comparison.Which could provide a theoretical basis for the application of different types of materials in practical engineering.The main research contents are as follows:?1?Designing the mix ratio of different types of materials,and testing their compressive strength,flexural strength and Brazilian disc splitting strength,and studying the different amounts of para-cut aramid fibers and different poly-ash ratios.The static mechanical properties of polymer and cement mortar with composite fiber and polymer,and the influence of various admixtures on the static mechanical properties of cement mortar.?2?The dynamic compression mechanical properties of different types of cement mortar materials under different strain rates(80s^-1,160s^-1,220s^-1)were tested by SHPB test device.The stress-strain curves and dynamic compression strengths at different strain rates were tested.The effects of fiber and polymer content and strain rate on the dynamic compression mechanical properties of cement mortar composites were studied.?3?The dynamic splitting tensile mechanical properties of different types of cement mortar materials under different strain rates(60s^-1,90s^-1,120s^-1)were tested by SHPB test device,and their dynamic split tensile strength,the energy dissipation and failure state were analyzed.The effects of fiber and polymer on the dynamic splitting tensile properties of cement mortar matrix were studied.The microstructure of the specimen was observed after the split tensile failure.The mechanism of action of fibers and polymers in cement mortar was discussed.?4?Using ANSYS/LS-DYNA finite element software to simulate the dynamic splitting tensile test of fiber polymer cement mortar,and analyze the dynamic failure process of the specimen during the internal propagation of stress wave under different strain rates.