Study On The Application Of Warm Mixing Thin-layer Overlay Technology

Hot mix asphalt mixture has many problems such as high construction temperature,high energy consumption and serious pollution,while in the course of road service,there exist many diseases such as rutting,cracks,pits and crowded waves,which have a very negative impact on road service function and traffic order.Therefore,it is necessary to adopt certain maintenance methods to maintain the road regularly.The technology of warm mix asphalt mixture thin-layer overlay combines the characteristics of low construction temperature,environmental protection,energy saving and good preventive maintenance effect of thin-layer overlay technology.It can solve the compaction difficulties and poor performance of traditional hot mix asphalt mixture thin-layer overlay caused by too fast cooling in construction project.Also,it has achieved the goal of energy saving and emission reduction to a certain extent,and has a positive role in promoting the sustainable development of road construction.In this paper,the technology of warm mix asphalt mixture thin-layer overlay is studied.Firstly,the performance of warm mix asphalt prepared by Sasobit and Evotherm was tested and analyzed.Then,the mix ratio of warm mix thin-layer asphalt mixture was designed and its related pavement performance was tested and evauated,and compared with hot mix thin-layer asphalt mixture.Finally,the pavement of warm mix thin-layer overlay was carried out on the test section,and the construction quality was checked and accepted.The results showed that,the change of the content of two warm mix additive has a significant effect on the performance of SBS modified asphalt.The optimum dosage of Sasobit warm mix additive and Evotherm warm mix additive was determined to be 3%and 0.7%respectively based on the analysis of penetration,softening point,ductility and viscosity.By testing the rheological properties of the two kinds of warm mix SBS modified asphalt binders at the optimum dosage,it was found that the effect of Evotherm on SBS modified asphalt at high and low temperatures was better than that of Sasobit.Finally,Evotherm warm mix additive was selected for the related research of warm mix thin layer asphalt mixture.SMA-10 asphalt mixture was selected for mix design of hot mix asphalt mixture and warm mix asphalt mixture,and the optimum asphalt-aggregate ratio was determined to be 6.2%.The dynamic stability of hot mix SMA-10 asphalt mixture and warmmix SMA-10 asphalt mixture at 60℃was5537 times per mm and 5726 times per mm respectively,the maximum bending strain of low-temperature damage is 3534 times per mm and 3123 times per mm respectively,the residual stability ratio of immersed Marshall test was 90.2%and 89.2%respectively and the residual strength ratio of freeze-thaw splitting test was 85.5%and 85.0%respectively.Warm mix thin-layer asphalt mixture had better high temperature compared with hot mix asphalt mixture.After paving the test road with warm mix thin-layer overlay asphalt mixture,the effect was good and the construction quality was qualified.Considering material cost and fuel cost comprehensively,the cost of paving1m²WMA could be saved by 0.8 yuan and the saving rate was 0.2%,the energy consumption could be saved by 60.67MJ and the saving rate was 11.7%,and the CO₂emission could be reduced by 10.14Kg/t and the emission reduction rate was 20.9%compared with the hot mix ashalt mixture.