Experimental Study On Influence Of Different Mesh Rubber Powder On Mechanics And Frost Resistance Of Lightweight Aggregate Concrete

In this paper,a new type of concrete material rubber lightweight aggregate concrete is prepared by using the abundant pumice and waste rubber resources in northern China.Considering the complex factors such as freeze-thaw and salt erosion in northern China,the freeze-thaw damage mechanism of rubber lightweight aggregate concrete under freeze-thaw condition and salt erosion freeze-thaw coupling condition is explored from the macro performance and microstructure.The main research results are as follows:(1)By testing the compressive strength,micro morphology and pore structure of rubber lightweight aggregate concrete,it is concluded that the addition of rubber can improve the frost resistance of rubber lightweight aggregate concrete.The compressive properties of 20 mesh rubber was the best.With the increase of rubber mesh,the minimum pore size,porosity and the porosity of < 1μm,1 ～ 10μm,> 10μm of rubber lightweight aggregate concrete first increase,then decrease and then increase.The GM(1,4)model is established by calculating the fractal dimension of pore diameter < 1μm,1～ 10μm and > 10μm,which can predict the compressive strength of rubber lightweight aggregate concrete.(2)By testing the macro properties and pore structure of rubber lightweight aggregate concrete in freeze-thaw environment,it is concluded that the addition of rubber can improve the frost resistance of rubber lightweight aggregate concrete and the relative dynamic modulus of elasticity can accurately characterize the performance of concrete freeze-thaw resistance.The results show that the concrete with 100 mesh rubber has the best frost resistance.The freeze-thaw damage and compressive strength loss of concrete can be judged by the change of 5 ～ 9μm pores.With the increase of 5 ～ 9μm pores,the freeze-thaw damage and compressive strength loss of rubber lightweight aggregate concrete increase,and vice versa.(3)Through the rapid freeze-thaw test of rubber lightweight aggregate concrete sulfate,the results show that the addition of rubber can improve the sulfate freeze-thaw resistance of rubber lightweight aggregate concrete.With the increase of rubber mesh,the frost resistance of rubber lightweight aggregate concrete first increases and then decreases,and the frost resistance of concrete with 100 mesh rubber is the best.The freeze-thaw damage and compressive strength loss of concrete can be judged by the change of 8 ～ 10μm pores.With the increase of 8 ～ 10μm pores,the freeze-thaw damage and compressive strength loss of rubber lightweight aggregate concrete increase,and vice versa.(4)The paper analyzes the frost resistance and salt frost resistance of rubber lightweight aggregate concrete by grey correlation entropy.The main factors influencing the compressive strength of rubber lightweight aggregate concrete are pore size ratio and free fluid saturation of 1-10μm pore,and the damage degree of freeze-thaw is mainly affected by the ratio of pore size and porosity of 1-10μm.