Experimental Research On Surface Modification Of Recycled Aggregate Of Reclaimed Asphalt Pavement Combined Machining

With the rapid development of road construction in China,the demand for asphalt pavement to be built and renovated is increasing year by year,and the demand for sand and gravel aggregates has maintained a continuous growth trend.After years of mining,natural sand and gravel resources have been rapidly declining,causing further problems such as soil erosion and ecological damage.If the asphalt pavement milling material is recycled,the aggregates in the waste asphalt concrete will be recycled,which will bring significant economic,social and environmental benefits.Therefore,it is necessary to study the preparation technology of waste asphalt concrete recycled aggregate.Based on the theory of impact surface modification of asphalt recycled aggregate,this paper proposes two methods of low temperature assisted impact type recycled aggregate surface modification and spray grinding type recycled aggregate surface modification.The main research results of the impact of key parameters on the surface modification effect of aggregates are as follows:(1)Using low-temperature-assisted impact surface modification method,an impact surface modification experiment was carried out for discarded asphalt concrete blocks,and the agglomeration and gradation in the recycled aggregate were used as evaluation indicators,aiming at the impact speed and cooling temperature.This factor has been experimentally studied,and a good separation effect has been achieved.(2)Carry out comparative experiments on discarded asphalt concrete using impact and spray-grinding surface modification technologies.Taking the gradation of recycled aggregates and the ratio of oil to stone as evaluation indicators,the research results show that the vertical impact surface modification method can effectively reduce the ratio of oil to stone of recycled aggregates,while the particle size integrity of recycled coarse aggregates modified by blasting surface modification High,reasonable arrangement of the surface modification process of the aggregate can improve the production efficiency of the recycled aggregate and obtain high-quality recycled aggregate.(3)The RESCO aggregate recovery test bed was built based on the principle of spray-milling surface modification,and three factors and four-level orthogonal tests were carried out for the influence of spray-grinding time and other factors on the surface modification effect.The results showed that the size of spray-grinding particles has a positive effect on the surface modification effect.The influence of each index is more obvious.When the particle size of the spray-grinding particles is in the range of 3-10 mm,the asphalt mortar on the surface of the recycled aggregate can be removed cleanly.The paper provides a new method of spraying and grinding surface modification for the preparation of high-quality recycled aggregates,which is beneficial to improve the resource utilization of waste asphalt concrete,and has good engineering practical application value.