Experimental Study On Mechanical Properties And Microscopic Mechanism Of Rubber Cement Mortar Modified By Micro-silica Powder

To effectively solve the "black pollution",this paper aimed at the industrial waste rubber into green new civil engineering materials this research hot spot test,for ordinary cement mortar,rubber particles of different sizes with 20% replacement rate to replace the rubber mortar made of sand and on the basis of the addition of different content,the modified rubber mortar specimens were designed under different curing ages of static uniaxial compression test,0.3MPa of dynamic compression impact test and under the same amount of stepwise creep loading test,and the influence mechanism of rubber particles and micro-silica powder on ordinary mortar was explained from the microscopic point of view.The main research results are as follows:(1)The static uniaxial compression test shows that the uniaxial compressive strength and elastic modulus of cement mortar at 7 d,14 d,and 28 d decrease significantly,while the peak strain increases.The addition of micro-silica powder significantly increases the strength and elastic modulus of rubber mortar.The addition of rubber weakened the mechanical compressive strength of mortar but helped to improve its brittleness to a certain extent,and the larger the rubber particle size was conducive to softening mortar and enhancing its deformation ability.(2)The dynamic impact test shows that the dynamic impact strain can be divided into elastic deformation stage,elastoplastic deformation stage and failure stage.The dynamic impact failure mode of ordinary mortar specimens is very broken and its integrity is completely destroyed.The dynamic impact strength decreases obviously after the addition of rubber,but the failure mode is also significantly improved.On this basis,adding micro-silica powder can further enhance its impact failure resistance and improve the structural of specimens.(3)The fractional creep test shows that the creep strain rises in a stepwise manner with the increase of time,the creep deformation caused by the addition of rubber particles increases,and the creep strain of rubber mortar decreases with the increase of the content of micro-silica powder.At the same stress level,rubber mortar has better creep resistance than ordinary cement mortar,and the creep resistance is further improved by the modification of micro-silica powder.The creep characteristics of mortar can be well reflected by Burgers model.(4)The microscopic mechanism analysis shows that the larger the particle size of the added rubber,the more sparse the structure.With the addition of micro-silica powder,the porosity of the rubber mortar specimen decreases gradually,and the relative wave velocity increases gradually.The micro-silica powder modified rubber mortar has almost no cracks and pores,and the microscopic appearance is the most complete and smooth.The hydration products and C—S—H gel of rubber mortar were the least.The addition micro-silica powder promoted the occurrence of cement hydration reaction,and honeycomb products were continuously generated during the reaction,the surrounding plate area was constantly enlarged,the internal pores and cracks were effectively filled,and the compact structure was formed as a whole.Figure [45];Table [14];Reference [88]...