Study On The Effective Utilization Ratio Of Old Asphalt For Central Plant Hot Recycling Mixture

Nowadays,with the arrival of overhaul and intermediate maintenance peak of highway in our country,people are continuing research on recycling technology of reclaimed asphalt pavement material(RAP)and has gotten results.It is of great significance to study the recycling technology of waste asphalt pavement for saving natural resources,protecting ecological environment and reducing the cost of repair and construction.At the same time,recycling of reclaimed asphalt pavement material(RAP)ensures the sustainable development of traffic and transportation effectively.Based on the needs of actual production,this paper selects one of the most commonly used recycling technologies,which is plant mixing heat regeneration technology,on the basis of deep research on asphalt pavement regeneration technology at home and abroad.This paper studies the improvement of the design method of hot recycled asphalt mixture and the improvement of the performance of reclaimed asphalt mixture.In this paper,the characteristics of old asphalt regeneration in hot recycling technology are studied.The basic composition of asphalt,the aging mechanism of asphalt and the mechanism of asphalt regeneration were studied,and the performance requirements and index standards of rejuvenating agent were analyzed,as well as the compatibility of rejuvenating agent with old asphalt.On this basis,the behavior characteristics of old asphalt in hot recycled asphalt mixture are analyzed.The utilization ratio of old asphalt in the process of recycling is neither as 0% in "black rock" hypothesis nor 100%,but as a certain value between them.When the amount of RAP is low and the aging of the old asphalt is not serious,it can be approximately assumed that the recycled asphalt is used completely.But if the amount of RAP is high,then the unused old asphalt can not be ignored.Therefore,start from the technical index of asphalt,the asphalt with different aging degree is obtained by experiments in this paper.The rejuvenation rate equation of old asphalt was established by seeking reasonable asphalt index parameters,and the effective utilization ratio of old asphalt with the high content of RAP was obtained by equation calculation.After determining the exact effective utilization ratio of the old asphalt under a certain dosage,the amount of new asphalt in the mix design of recycled asphalt mixture is adjusted according to the utilization ratio,so that a more suitable design can be obtained.Finally,use the recycled asphalt mixture's road performance test,to verify establish of this method.In this paper,the effective utilization ratio of old asphalt is 82.3% by the equation of effective utilization of old asphalt.The rejuvenate test of old asphalt determined the type A of rejuvenating agent and the amount of 10% addition of rejuvenating agent.Then indoor test was carried out to verify the effect of optimized design and reclaimed asphalt mixture after adding additives and rejuvenating agent.The test results show that the road performance of the recycled asphalt mixture after optimization is not different from that of the mixture with recycled agent,and it can completely meet the requirements of technical specifications.And compared with the recycled asphalt mixture's road performance without optimized,the effect is very significant,especially the water stability and fatigue properties can be greatly improved.