Fracture Behaviors Analysis Of Hot Recycled Asphalt Concrete Based On Fracture Mechanics

Recycling of recycled asphalt pavement（RAP）has many advantages,such as reducing greenhouse gas emissions,reducing the use of raw materials,reducing costs,and reducing energy consumption;the application of RAP can also contribute to the realization of‘carbon peaking’and‘carbon neutrality’.Pavement cracking is the main disease form of recycled asphalt concrete.Based on this,this paper studies the effect of RAP content and rejuvenator on mode I and mode II fracture performance of recycled asphalt concrete according to the theory of fracture mechanics.The conclusion provides an important reference for the durability design of recycled asphalt concrete pavement.The main research contents and results are as follows:（1）The basic properties of RAP were tested in the laboratory.The test results show that the basic physical and mechanical properties of the RAP aggregate are slightly lower than that of the new aggregate,and its variability needs to be controlled during the use process;with the increase of the recycled asphalt content,the performance of the mixed asphalt gradually declines,and the rejuvenator can improve the performance of the mixed asphalt.（2）Based on the concept of the equivalent energy method,the equivalent stress intensity factor parameter(K_ΙC^*)is proposed,which can realize the unified evaluation of the medium and low temperature fracture performance of HMA.Mode I fracture test was carried out to study the effect of RAP content and rejuvenator on the fracture performance of recycled asphalt concrete.The results show that at low temperature（-10℃and 0℃）,RAP reduces stress intensity factor（K_{I C}）and fracture energy（_FG）;at medium temperature,the J-integral value and K_ΙC^* value increase with the increase of RAP content;the rejuvenator could improve the fracture resistance of hot recycled asphalt mixture;the equivalent stress intensity factor(K_ΙC^*)is feasible to evaluate the medium temperature fracture performance.（3）According to the experimental principle of the unilateral symmetrical loading test of the cement concrete,a method was proposed to measure the mode II fracture performance of HMA,and the calculation method of mode II fracture evaluation index（stress intensity factor and fracture energy）was given,and the effect of RAP content on mode II fracture properties of recycled asphalt concrete was studied.The results show that with the increase of the RAP content,the fracture performance decreased gradually;the rejuvenator can improve the resistance to mode II fracture.At the same time,the asymmetric semi-circular bending test verified the feasibility of the mode II fracture test method proposed in this chapter.75 Figures.21 Tables.98 References...