The Performance Of Permeable Asphalt Concrete With Double Modified Recycled Coarse Aggregate

In order to realize the resource utilization of construction waste and in response to the construction concept of sponge city,the recycled coarse aggregate was 100%replaced by natural aggregate and mixed with asphalt to form permeable asphalt mixture(PAM).The recycled coarse aggregate was double-modified,and the natural coarse aggregate was replaced with 100% substitution rate,and the effects of double-modified recycled coarse aggregate on the optimal asphalt to stone ratio,low temperature crack resistance,high temperature performance and water stability of permeable asphalt concrete were studied.(1)In the first modification,the old mortar is peeled off,and in the second modification,the recycled aggregate is denser.Reclaimed coarse aggregate was modified by soaking in glacial acetic acid(RCA-1-G),soaking in sodium silicate solution(RCA-1-S)and soaking in glacial acetic acid first and then soaking in sodium silicate solution(RCA-2-GS).The results show that the double modification method is better than the one modification in improving the optimal asphalt to stone ratio,low temperature crack resistance,high temperature performance and water stability of asphalt mixture.Compared with the untreated recycled aggregate mixture,the residual stability and the freeze-thaw splitting tensile strength ratio in the water stability of the mixture are increased by 8.9% and 6.6%,respectively,and the dynamic stability of the mixture at high temperature is increased by 4.66 times.The effect of improving the low temperature cracking strength is not obvious.(2)The first modification makes the recycled aggregate enhance the adhesion,the second modification considers the reaction with asphalt.The recycled coarse aggregate was modified by soaking primary modified recycled aggregate with polyvinyl alcohol(RCA-1-P),wrapping primary modified recycled aggregate with cement mortar(RCA-1-C)and double modified recycled aggregate treated successively with polyvinyl alcohol and cement mortar(RCA-2-PC).The results show that the optimal asphalt ratio of the primary modified polyvinyl alcohol recycled aggregate is lower than that of the untreated recycled aggregate,and the primary modified cement mortar and double modified cement mortar lead to an increase in the optimal asphalt ratio of the mixture.Compared with the untreated recycled aggregate mixture,the residual stability and the freeze-thaw splitting tensile strength ratio are increased by 11.7% and 7.0%,respectively.2%;It has a positive effect on the high temperature performance of the mixture,but has a negative effect on the low temperature crack resistance.(3)The function of the first modification is to fill and repair the recycled aggregate,and the second modification makes the recycled aggregate have the characteristics of hydrophobicity.The slag solution was used to soak the reclaimed aggregate(RCA-1-SL),the silane coupling agent solution was used to soak the reclaimed aggregate(RCA-1-SC),and the slag solution and silane coupling agent solution were used to soak the reclaimed aggregate(RCA-2-SLSC)successively.The results show that after the three aggregate modification methods,the optimal asphalt-stone ratio of the mixture decreases a lot,especially the effect of double modification,which decreases by 13.7%.The water stability performance,high temperature performance and low temperature crack resistance of asphalt mixture are improved well.