Study On Mix Proportion Design And Performance For Hot In-place Recycling Of Asphalt Pavement In WuJi Expressway

In recent years,the expressway develops rapidly in China,the mileage ranks number 1 in the world.At the same time,the pressure of expressway maintenance is increased.The asphalt concrete pavement is widely used in China's expressway,its maintenance projects must product lots of waste asphalt mixture,which will pollute the environment and waste the resources if they are disposed incorrectly.At present,the transport industry insists the development concept of “protecting environment,saving resource”,recycling waste asphalt mixture is necessarily adopted.Recycling waste asphalt mixture not only saves the resources,but also protects the environment,the technology of hot in-place recycling has the proprieties of short constructing time and less influencing traffic,which is widely used all over the country and takes good effects.Its key technology is mix design of new asphalt mixture.In the paper,by example of Wu Ji expressway maintenance project,the empirical study is applied to research this kind of technology.The research includes: field core sampling on Wu Ji expressway maintenance project;testing and evaluating the performance of waste asphalt mixture aggregate material and asphalt;analyzing the improvement effects of new asphalt and regenerant to RAP.according to design standards,designing and trial-mixing mix proportion of new asphalt mixture;analyzing influence of blending temperature,blending time and crushing degree to new asphalt mixture;ascertaining mineral aggregate gradation,optimum asphalt content and regenerant dosage;evaluating new asphalt mixture performance;analyzing its construction technological progress and measures of controlling the quality.The results show that the technology of hot in-place recycling technology is suitable of mild disease of asphalt pavement;the new asphalt and regenrant have improvement affect on RAP performance;on Wu Ji expressway maintenance project,optimum asphalt content 4.4~4.6%,better regenerant dosage 1~3%;the blending temperature and blending time have great influence on new asphalt mixture performance,RAP crushing degree has little influence on its performance.