Comprehensive Evaluation And Analysis Of Influencing Factors Of Crack Resistance Of Asphalt Mixture Based On Disc-shaped Compact Tension Test

The rapid development of transportation industry requires more and more for the safety and reliability of roads.As one of the most commonly used materials in road construction,asphalt mixture has an important impact on the service life and safety of roads.By deeply studying the crack-resistant properties of asphalt mixture,the characteristics and properties of materials can be better understood,thus providing more reliable and safe materials for road construction.First of all,the Disc-shaped Compact Tension(DCT)analyzes the influence of different temperature,different void ratio,different aging conditions and RAP dosage on the crack resistance of the mixture,compares the correlation between the existing fracture evaluation indexes and the frequency distribution of the fracture evaluation index,and demonstrates the rationality of the five types of fracture index as the crack resistance-performance evaluation index of asphalt mixture.The results show that when the fracture energy is used as the evaluation index,the PPA + SBS modifier has the best modification effect and the Elvaloy + PPA modifier is the worst;the temperature,void rate and aging condition directly affect the fracture energy of the mixture: the higher the temperature,the deeper the aging degree,the smaller the fracture energy.Based on the theory of linear elastic fracture,the constitutive model and contact constitutive model of asphalt mixture are established.Two-dimensional finite element numerical simulation of the DCT specimen was conducted,and the stress,strain,displacement distribution and deformation of the DCT specimen were also simulated and analyzed.The study shows that the fracture process of DCT specimen can be divided into initial loading stage,specimen damage stage,fracture generation stage,fracture expansion stage and complete specimen damage.The calculation results are in good agreement with the test results and can provide a reference for the DCT test.After evaluating the existing fracture index,a new fracture index is proposed:post-peak energy index-PPI(Post-peak Power Indicator),and the consistency test and correlation coefficient within the group are tested.The test results show that PPI can be used to evaluate the low-temperature fracture performance of asphalt mixture.Finally,the principal component-entropy method is used to establish the comprehensive evaluation index Zn based on six types of fracture indexes such as peak energy index and fracture energy.Zn comprehensively considers the correlation between the indexes and unifies each index,so that different fracture indexes can be compared and comprehensively evaluated.The results analyze the influence of asphalt mixture,and the importance of the four categories: void ratio > temperature >RAP content > aging degree.In the design process and construction process of the asphalt mixture,the indexes of the asphalt mixture can be monitored according to this conclusion to ensure the quality and performance of the asphalt mixture.