Experimental Study On Performance Of Large Proportion RAP Warm Mixed Recycled Asphalt Mixture

In response to the country's call for building a “powerful country” and “the development of beautiful China”,after the rapid development of China's road network,a large number of asphalt pavements will enter the stage of maintenance,repair and expansion,resulting in a large amount of discarded asphalt pavement materials.For the sustainable development of road construction,the recycling of recycled asphalt pavement(RAP)is an inevitable trend in the development of pavement maintenance.However,the high temperature and low RAP utilization rate of the asphalt mixture in the domestic plant mixed heat regeneration technology greatly restricts the reuse of RAP.This paper intends to study the large-scale RAP warm mixed regeneration asphalt and its mixture.The relevant research contents and conclusions are summarized as follows:Firstly,the performance analysis and evaluation of the old asphalt and recycled mineral materials were carried out on the upper layer of the road surface of the Jiefei Expressway in Guangdong Province and the upper layer waste asphalt mixture in the urban road of Huizhou City.According to the different mass ratio of new and old asphalt with different RAP content,the composite asphalt was configured and its basic technical indexes were evaluated.On this basis,the mechanism of reheating and regenerating modification of regenerant A and regenerant B with different dosages was studied.The energy angle is discussed in terms of its microscopic mechanism.It has been determined by research that the amount of regenerant A recommended is 5% of the total mass of the asphalt,and the amount of regenerant B recommended is 4% of the mass of the old asphalt.Then,the mixture ratio of different RAP mixed temperature modified reclaimed modified asphalt mixture is designed.According to the Marshall method,based on the volume index control principle,the RAP and GAC-16 gradation of large particle size will be determined.Mixing ratio of warm mixed regeneration modified asphalt mixture with %,20%,30%,40% and 50% RAP blending ratio.The optimum mixing and compaction temperature of large proportion of RAP warm mixed regeneration asphalt mixture was determined by multiple temperature Brookfield viscosity test and variable temperature compaction test.For high temperature and rainy climate,the hightemperature deformation resistance and the evaluation of water damage resistance of the mixture was tested by indoor mix performance test.Finally,based on the basic national policy of protecting the environment and the green development policy,the harmful emission detection of large proportion of RAP warm mixed regeneration asphalt mixture was tested by laboratory test,and the social environmental benefits are evaluated based on the test results.The results show: The water damage resistance of the large proportion of RAP warm mixed regeneration asphalt mixture is better than that of the new hot mix asphalt mixture,and the high temperature deformation resistance is similar to the new hot mix asphalt mixture.Compared with the hot mixed asphalt mixture,it has better water damage resistance and lower temperature resistance.The 40% RAP ratio warm mix regenerated modified asphalt mixture has the best performance.In this paper,considering the performance,environmental protection and economic factors,the recommended amount of RAP is 40% to 50%.Large proportion of RAP warm mixed regeneration asphalt mixture has excellent environmental protection and good economic benefits,and will have broad application prospects.