Research And Application Of Heat Regenerating Of Recycled Asphalt Mixture On Asphalt Pavement

With the rapid development of road construction,diseases have occurred on the roads constructed in early age.The age has come when the roads that were constructed earlier are being maintained or repaired in succession.Influenced by vehicle load and natural environment,such disease as wheel ruts,cracks and loose surface occurred on asphalt pavement.On one hand,they are caused by the constructing factors and materials;on the other hand,they are also the results of the inevitable aging of asphalt in its service.As for serious damage on the surface of the roads,milling-planning before asphalt re-paving is usually adopted,which will waste not only large amount of asphalt mixture but also road maintaining funds.Pavement recycling technology saves road maintaining funds as well as protects environment since waste asphalt mixture was used to roads re-paving.How to recycle waste asphalt mixture into regenerated asphalt mixture effectively is worth further study.Fusion test of regenerated asphalt and new asphalt and the rate of utilization of recycling asphalt pavement material(RAP)are further explored in the paper.The mineral aggregate gradation and extraction test results show that the gradation of RAP does not meet the requirements of the present code,and performance degeneration of recycled asphalt is quite serious.At the same time,the,Marshall designing method is studied systematically in the procedures of the determining of optimum asphalt content,the designing of aimed proportioning and the testing of producing proportioning.The mix ratio of regeneration AC-25 mixture of 30%,40%,50% have been studied comprehensively.The results show that:(1)With 0,9.2%,16.4%,33.3%,66.7%,85.3% of the new asphalt content,the mark number of regenerated asphalt is 25.6,29.4,33.6,38.2,48.5,and 63.3 respectively.It can be concluded from the test that the mark number of regenerated asphalt increases with the rate of new asphalt.It shows that the more proportion of new asphalt,the more penetration of regenerated asphalt.(2)With 30%,40%,50% of the recycled asphalt content,the proportion of new asphalt is 3.26%,2.75%,2.46% respectively.The results show that,with the increase of recycled mixture content,the proportion of new asphalt decreases.(3)With the method of Saal,tests on different proportion of asphalt content(0%,20%,30%,40%,50%,100%)show that the optimum blending temperature for new and recycled asphalt is 156.9℃,172.5℃,179.7℃,187.1℃,194.6℃,227.6℃,the optimum temperature for constructing is 144.5℃,156.7℃,163.6℃,170.7℃,177.9℃,210.6℃.The optimum blending and rolling temperature rises with the increase of recycled asphalt.(4)Test on the high and low temperature performance,water stability of the recycled asphalt mixture of 30%,40%,50% blending rate is carried out.The results show that the high temperature performance of asphalt mixture is improved with the increase of recycled asphalt content in the old asphalt pavement;the water stability and low temperature performance is lowered.