| In this paper,the recycled aggregate and natural pumice stone are set as coarse aggregate,pumice stone is replaced with recycled aggregate in equal volume.From the macro and micro aspects,the study is about the basic mechanical properties and durability of the mixed aggregate concrete when the replacement rates of recycled aggregate are respectively in 0%,30%,50%,70%,100%,which aims to screen out the optimal replacement rates.The results shows that:with the increase of the replacement rate of recycled aggregate,the cube compressive strength of mixed aggregate concrete is gradually increasing,and the splitting tensile strength of mixed aggregate concrete which is the split rate of 30%for the sector rise first and then decrease;After analysis of mass loss,relative dynamic modulus of elasticity loss and appearance spalling,it was found that the mixed aggregate concrete showed the good frost resistance when the replacement rates of recycled aggregate are in 50%and 70%;When the replacement rate of recycled aggregate increased,the void content in the mixed aggregate concrete decreased.The results showed that the best replacement rate of recycled aggregate was in 50%.Then the waste tire rubber powder which was mixed into the concrete was used for further modification research.The particle size of waste rubber powder were respectively 20 meshes,60 meshes,80 meshes,100 meshes and 120 meshes.Then mixing them into the concrete according to the amount of 3%,6%,9%of the cemented materials,to analyze the mechanical properties and microstructure of mixed aggregate concrete at early stage.The results showed that the waste rubber powder increased the compressive strength reduction rate of mixed aggregate concrete under the same particle size;The environmental scanning electron microscope showed that rubber powder,recycled aggregate,pumice and cement interface are weak areas which was the main reason for the decrease of the strength of mixed aggregate concrete. |
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