Design And Performance Evaluation Of Cold Patching Asphalt Mixture Based On Reclaimed Asphalt Pavement Materials

In the current pothole repair process,cold patching asphalt mixture has the advantages of being able to be mixed at room temperature to reduce energy consumption,being able to be constructed around the clock without seasonal restrictions,and being stored in bags to avoid waste,which has attracted extensive attention from scholars at home and abroad.However,the high price of high-performance cold patching asphalt restricts its application in road maintenance.In addition,my country’s high-grade highways have entered a stage of large-scale renovation and maintenance,and the annual output of RAP is increasing.Although researchers have achieved fruitful results in the research of RAP reuse technology,there are still complex production processes in the actual application process,secondary aging of old asphalt and insufficient diffusion of old and new asphalt,which seriously affect the utilization rate of RAP.If the cold patching technology and the recycling technology are combined,complementary advantages can be achieved.On the one hand,the addition of RAP can reduce the cost of cold patching asphalt mixture;provide sufficient time for diffusion.However,at present,there is a lack of research work on recycled cold patching asphalt mixture,and there is no report on the preparation of recycled cold patching asphalt mixture by RAP.Therefore,this thesis studies the preparation and performance of recycled cold patching asphalt mixture.First of all,in order to analyze the change of the diffusion degree between the old and new asphalt in different storage periods,SEM and FTRI were used to evaluate the diffusion degree between the new and old asphalt from the microscopic appearance structure and functional group index of the asphalt material respectively.The degree of diffusion between asphalts increases with the increase of storage time,which further verifies that the storage time has a promoting effect on the recovery of old asphalt properties.Then,referring to the results of research at home and abroad,cold patching asphalt and recycled cold patching asphalt mixture were designed,and contact angle test,mixing test and binder drainage test were selected to complete the selection of cold patching asphalt formula and primary selection of recycled cold patching asphalt mixture.During the selection of cold patching asphalt formula,the contact angle between old and new asphalt was taken as an important control index,and the cold patching asphalt mixture formula used in this thesis was determined by the contact angle test results.In the estimation of the optimal asphalt dosage range of the recycled cold filling asphalt mixture prepared by undisturbed RAP and the recycled cold patching asphalt mixture prepared by RAP treated by 2.36 mm standard sieve,the mixing test and the leakage test were used to determine the minimum asphalt dosage and the maximum asphalt dosage respectively.Finally,the workability,strength,resistance to water damage resistance and low temperature cracking resistance of the initially selected recycled cold patching asphalt mixture after different storage periods were tested.The cold patching asphalt mixture CPAM-4.5 has obvious advantages in terms of early strength and moisture sensitivity.At the same time,after a comprehensive comparative analysis of all test results,the recycled cold patching asphalt mixture RAP-CPAM-2.4A was selected to continue the wheel tracking test,Hamburg wheel-tracking test and low-temperature trabecular bending tests.According to the test results,it was found that RAP-CPAM-2.4A was resistant to deformation capability and resistance to water damage are superior to CPAM-4.5,and this advantage increases with storage time.From this point of view,it is feasible to completely use RAP to prepare regenerative cold patching asphalt mixture.