Study On Stickiness Of The Rap In Rotating Drum For Hot Mix Recycling Of Asphalt Mixture

Asphalt pavement recycling technology helps dispose RAP,save energy sources and protect environment.Meanwhile it is beneficial to our economy and society.This paper based on the research object of hot mix plant recycling technology,and mainly study on stick material in rotating drum for hot mix recycling of asphalt mixture.This paper begins with the study of rotating drum of hot mix recycling.Through the comparison and analysis the existing downstream heating drum recycling equipment,counter-current heating drum recycling equipment,continuous double drum recycling equipment,triangle drying heat recycling equipment,vertical drying heat recycling equipment and the 100% recycled material production recycling equipment,their advantages and disadvantages were studied in detail from different perspectives.Then,by the analysis of the producing stick material and the condition of stick force of RAP heated in the drying drum,the conditions for the sticky material separated from the rotating drum are obtained.Using the finite difference spherical particle model,the particle diameter,the thermal diffusivity and the initial temperature of RAP were analyzed and verified by using the MATLAB tool to influence the heating time of the old asphalt mixture.The experimental study on RAP provided by the hot recycling site shows that the particle diameter of RAP below 5mm exceeds 60%,indicating that the fine RAP is too much;the amount of stick material and the stick force of steel plate of the RAP under different heating temperatures are analyzed,and both are consistent when the temperature of the RAP is heated between 123.7°C and 135.1°C;In practice,reasonable heating range should be controlled within the range of 130 °C ~ 140 °C,the stick degree of the hot RAP is minimal.Finally,combined with the previous theoretical research and experimental analysis,the paper proposes to solve the stick material of rotary dryer by controlling heating temperature and regular maintenance,improving the structure and blade shape of rotary dryer,separating the particle diameter of RAP below 5mm by the cold+hot recycling or recycling ring of rotary dryer.and simple analysis of RAP screening and storage.