Research On Static And Dynamic Characteristics And Durability Of Polypropylene Fiber-modified Rubber Foamed Concrete

With the massive construction of transport infrastructure,the resulting operation and maintenance costs have increased sharply.Among them,the fatigue damage of engineering structures caused by long-term traffic dynamic loads and the impact of vibration and noise on the surrounding environment has aroused widespread concern in engineering and society,and energy absorption and vibration-damping materials have become a research hotspot in recent years.In comparison,foamed concrete has typical characteristics of lightweight,high strength,self-leveling and porous vibration absorption,and has been widely used as backfill in highway,railway,municipal and other projects,with good application results.However,experiments have found that traditional cement foamed concrete has a relatively high stiffness and is prone to fatigue damage under long-term dynamic loads,leading to progressive failure of the pore structure,which is detrimental to the durability of engineering structures.It is necessary to take measures to further improve its energy absorption,vibration damping,and fatigue resistance characteristics.For this reason,this paper proposes a new material of polypropylene fiber-modified rubber foamed concrete,systematically carries out static and dynamic strength experiments,elastic modulus experiments,durability experiments,and simulation analysis of application effect,reveals the change of key mechanical indicators and influencing factors,and verifies excellent performance.Based on the research results,the following conclusions are drawn:1.The compressive strength and flexural strength of polypropylene fiber-modified rubber foamed concrete were positively correlated with the wet density,negatively correlated with the rubber admixture,and parabolic change with the rubber particle size and fiber admixture.According to the impact experiment results,the optimum rubber particle size,rubber admixture and fiber admixture are:20 mesh,20%and 0.3%respectively.2.The static modulus of elasticity and dynamic modulus of elasticity of polypropylene fiber-modified rubber foamed concrete increased with the increase of wet density and decreased with the increase of rubber admixture,but the relationship with fiber is not obvious,and the values were smaller than that of traditional foamed concrete.Based on the correlation analysis between the static and dynamic modulus of elasticity and the compressive strength,the equations for the static and dynamic modulus of elasticity under different proportioning conditions were established through the factor conversion coefficients.3.Based on durability experiments,which was revealed that the water stability,impermeability,freeze-thaw resistance and fatigue resistance of polypropylene fiber-modified rubber foamed concrete were better than that of traditional foamed concrete,especially the cumulative plastic deformation during fatigue loading was significantly improved,showing excellent usability.4.Based on the SEM experiments,the distribution characteristics of the rubber,fiber and pore structures were discovered,revealing the microscopic mechanism of its energy absorption and vibration-damping.At the same time,the structural dynamics of semi-rigid asphalt pavement was analysed to further validate the effect of polypropylene fiber-modified rubber foamed concrete in the application of energy absorption and vibration-damping in engineering.