Experimental Study Of Evotherm Warm Recycled Asphalt Mixture

The peak of our country's highway construction has passed,Then came a lot of pavement maintenance work.Our country produces nearly 50 million tons of RAP every year on maintenance of highways,If we don't make use of it,we will cause a lot of waste of resources.The recycling technology of asphalt mixture can play the role of making use of reclaimed materials that are planed down.But at present,it is recognized that the hot in-plant recycling technology with stable performance has the disadvantages of low mixing amount of reclaimed material and higher production temperature than ordinary hot mix asphalt mixture.By adding warm mixing agent,this kind of problem can be well solved.Based on Evotherm,a widely used warm mix agent for warm mix asphalt is studied in this paper.Using RTFOT to simulate short term and long term aging asphalt,the changes in macro performance,component content and chemical composition of asphalt aging and regeneration were obtained through the test of asphalt conventional index,four component analysis and infrared spectroscopy.On the basis of the above three aspects,the aging degree of the recycled asphalt in the actual pavement is evaluated and the recovery of recycled asphalt is analyzed.The results show that the recycled asphalt has a deeper aging degree compared with the simulated 5-6 years,and there is a significant difference in the relative content of the recycled asphalt and the simulated long-term aging asphalt in the Sulfoxyl functional group,and the recovery effect is better after the regenerator is added to the reclaimed asphalt.The mixture ratio of RAP mixed with 30%,40%,50%and 60%is designed.Using the principle of equal volume,the relation curve of the void ratio and the compaction temperature is obtained by the method of variable temperature compaction.The mixing and compacting temperature of the mixed asphalt mixture with different RAP content is determined with the target void ratio as the standard.The change rule of warm mixing effect with the increase of RAP content is obtained.By comparing the hot recycled asphalt mixture with the same mixture ratio,the compacting compaction temperature of warm mix recycled asphalt mixture can be reduced by 10-27 degrees.At last,the performance of four kinds of RAP mixed hot and recycled asphalt mixture was evaluated.The high temperature stability,low temperature crack resistance and water stability test showed that the high temperature performance of the regenerated asphalt mixture was improved with the increase of RAP content,and the low temperature performance and water stability were obtained.The RAP content of warm mix recycled asphalt mixture can he increased to 40%when the performance of the mixture is reduced.The effect of RAP addition on the durability of warm mix asphalt mixture was studied by comparing the low temperature cracking resistance and water stability of warm mix asphalt mixture before and after aging.The results showed that the regenerated asphalt mixture had good aging resistance.