Application Research Of Foam Asphalt Cold Recycling In Tianjin Expressway

Foam cold recycled asphalt mixture(Foam cold recycled asphalt mixture)has been used for road base engineering materials for a long time.In order to give full play to the residual performance of waste asphalt pavement materials(RAP),the recycled foamed asphalt cold recycled mixture in Tianjin High-speed application performance is more excellent.This study relied on the Tianjin high-speed large and medium repair asphalt pavement regeneration project,optimized the mix ratio of the foamed asphalt cold recycled mixture,determined the best way to maintain the foamed asphalt cold recycled mixture,and explored the promotion of foamed asphalt cold recycled Performance measures.First,the performance of recycled waste asphalt pavement materials(RAP)is evaluated.At the same time,according to the design requirements of the large and medium repair pavement regeneration project of Tianjin Expressway,three types of foam asphalt cold recycled mixture mineral mix ratio were selected.Based on the target RAP blending ratio,the effect of foamed asphalt dosage on the performance of the mixture was explored.The asphalt mixture specimens prepared with different amounts of foamed asphalt were tested for split strength,water stability and fatigue strength.The test results showed that with the increase in the amount of foamed asphalt,the water stability and splitting of the foamed asphalt cold recycled mixture The strength increases first and then decreases,and the fatigue life decreases overall.By reducing the passing rate of each screen hole below 2.36 mm by 1% to 5%,saving the amount of fine aggregates by 4% to 8%,the gradation range of cold recycled mixture is optimized,and the mix ratio design of foamed asphalt cold recycled mixture is designed.In order to improve the compaction degree of the asphalt pavement regeneration project of Tianjin Expressway's large and medium repair,foamed asphalt cold recycled mixtures were formed according to the traditional Marshall method and vibration compaction method.In this study,through the correlation between the maximum dry density and the optimal water content,the best compaction process used in the project was determined.The test results show that,compared with the Marshall method,the split strength of the cold recycled mixture using the vibration compaction method is increased by 30.0%,the water stability is improved by 5.7% to 16.1%,and the dynamic stability is improved.The frequency of 30.7% ~ 51.0% is conducive to the end of health.In order to improve the performance of the asphalt mixture,cement was selected.After adding the cement,the road performance changes of the foamed asphalt under different dosages were studied,and the initial strength of the mixture after cement addition was obtained by single factor analysis of variance.And its water loss resistance has been significantly improved;with the increase of cement content,the strength,high temperature stability and water stability of the mixture have been improved;the addition of cement will reduce the low temperature crack resistance of the asphalt mixture;Combined with the specification requirements of asphalt mixture road performance,it is recommended to add cement to the cold recycling of foamed asphalt,and the cement content should be controlled between 1% and 2%.Simultaneously,a simulation study of cold accelerated foam asphalt cold-recycled mixture in indoor was conducted.By comparing with the performance of cold recycled foam asphalt mixture under natural curing period,the poor performance of the mixture under accelerated curing conditions and natural curing conditions was used as the criterion.In the end,60 ° C for 24 h is the best way to accelerate indoor health.In the end,a high-speed foam asphalt cold-recycled mixture was used for construction at a high speed in Tianjin,the construction process and process were optimized,and the feasibility of indoor accelerated health maintenance was verified.And follow-up test on the road.