The Key Technology Research Of Mix Design Of Central Plant Hot Recycling

Cental plant hot recycling technology is the most widely used in China and even the world.Along with our country’s highway which built in early time has gradually enter the period of medium maintenance or major overhaul,in this case it would generate a lots of RAP.If we can make rational use of RAP,which can not only reduce the demand for virgin aggregate and virgin binder,but also can save the cost of construction,so as to realize the sustainable utilization of resources.Though China has carried out research on asphalt pavement regeneration technology recently,some problems still lack of attention,such as Such as a new type of recycling agent was developed to improve the regeneration rate of aged asphalt,a literature search was conducted on predicting the virgin aggregate temperature required to dry and heat RAP in a hot-mix asphalt(HMA)production plant,and the curing characteristics of recycled asphalt mixture.In this paper,the research on the following some aspects is carried out in the core of central plant hot recycling.When asphalt regeneration agent development is studied,this paper on the basis of summarizing the ingredients contained in the regenerant at home and abroad,a variety of new regenerators were prepared according to the orthogonal design of the materials containing different components contained in the regenerant.Through range analysis and variance analysis of the orthogonal test results of recycled asphalt preferred a new type of regenerator,then put it with the other two commercially available regenerators together to evaluate the use effect,it is verified that for the ductile index,recycling agent of the invention is obviously superior to the other two commercially available regenerators,and the anti-aging ability of the recycled asphalt is better than that of the matrix asphalt.When the temperature change characteristics of the recycled asphalt mixture during the mixing process is studied,this paper based on the analysis of factors that affect the heat transfer of virgin aggregate,the infrared thermal image formed by infrared camera and Image-Pro Plus software were used to study the change of temperature between virgin aggregate and RAP with the extension of mixing time.It is concluded that when mixed to 4 min the temperature difference become very small,and RAP content,RAP water content and virgin aggregate heating temperature will have an effect on the discharge temperature of asphalt mixture.When the mix design of recycled asphalt mixture is studied,this paper based on the Marshall design method to carry out the original AC-20 asphalt mixture mix design,mix design of 20%RAP recycled asphalt mixture,mix design of 40%RAP recycled asphalt mixture and mixing ratio design of recycled asphalt mixture with 40%RAP and adding regenerant,so as to determine the plant mixed hot mix of mixed materials in different RAP content and the addition of renewable agent before and after the best amount of asphalt.The results show that the addition of recycled agent and the change of RAP content will affect the optimum asphalt dosage and mix design parameters of recycled asphalt mixture.Finally,the curing characteristics of recycled asphalt mixture were studied by using crushed RAP and loose RAP.The change of RAP content and mixing time was used to analyze the law of change of the Marshall stability,splitting strength,VV,dynamic stability.The experiment show that the application of crushed RAP is appropriate and curing time is appropriate for 2d.