Study On Performance Of Foamed Asphalt And Its Cold In-Place Recycled Asphalt Mixture

Aiming at the maintenance,repair and reconstruction for the road which was constructed in early years,the research object of this study was the foamed asphalt and its cold recycled mixture.With this study,the purpose was to save the mixing and transportation cost of asphalt mixture,reduce energy consumption and protect the ecological environment.In this study,large numbers of laboratory tests had been carried out on the forming of foamed asphalt and design method of the foamed asphalt cold recycled mixture.Firstly,based on the analysis of the foaming principle and evaluation index of asphalt,the foaming experiment of asphalt under different foaming conditions was carried out to study the foaming characteristics of asphalt and its influencing factors.Secondly,the mixing ratio design was carried out for the foamed asphalt cold recycled mixture.With a certain amount of new aggregate,water and foamed asphalt,the optimal moisture content of the cold recycled mixture was determined by compaction tests.The optimal content of foam asphalt was obtained according to the results of splitting strength and immersion splitting strength tests.Finally,the pavement performance of foamed asphalt cold recycled mixture was analyzed.With different content of foamed asphalt and cement,the influence on the water stability,low temperature cracking resistance and high temperature stability of cold recycled mixture was investigated.At the same time,the differences of water stability and low temperature cracking resistance of cold regenerated mixture were studied under different curing conditions.The results showed that the expansion rate of SK90,SK70,KL90 and KL70 matrix asphalt had a good correlation with the foaming temperature,foaming water consumption and the technological parameters during the foaming process.There was a good correlation between the maximum dry density and water content of recycled asphalt mixture.The content of cement had great influence on the determination of the optimum content of foamed asphalt.The content of cement and foamed asphalt had significant influence on the pavement performance of recycled asphalt mixture.The comprehensive pavement performance of recycled asphalt mixture obtained the optimum value when the cement content was 3% and the foamed asphalt content was 4%.