Size Effect and Influence Factors of Asphalt Mixture Based on Particle Discrete Element

To explore the size effect of asphalt mixture, asphalt mastic asphalt mixture was taken as the research object, and the uniaxial compressive strength was used as the evaluation index. The applicability of the three size effect theories of Bazant, Carpinteri, and Weibull were evaluated, and the corresponding size effect law parameters were calculated. The critical dimensions and critical strength of the asphalt mixture were determined, and the effects of coarse aggregate properties, maximum nominal particle size, and loading rate on the size effect of asphalt mixture were analyzed. Results show that the asphalt mixture has an obvious size effect phenomenon, and the uniaxial compressive stress-strain curves of asphalt samples with different sizes have the characteristics of compaction stage, elastic stage, and transition from plastic deformation to failure stage. The uniaxial compressive strength of the asphalt mixture is negatively correlated with the sample size, and as the sample size increases, the strength reduction decreases gradually. With the increase in the elastic modulus of the coarse aggregate, the critical strength value increases continuously, and the critical dimension decreases. As the maximum nominal particle size increases, the critical dimension and critical strength increase gradually. With the increase in the loading rate, the critical strength continues to increase, and the critical dimension gradually decreases. The Bazant and Carpinteri size effect laws are more suitable for the analysis of the size effect of asphalt mixture, while the Weibull size effect law has a large error. When SMA is used as the pavement structural layer, the ratio S of the structural layer thickness to the maximum nominal particle size calculated by the Bazant size effect law is 2.6 to 3.5, and the S range calculated by the Carpinteri size effect law is 2.6 to 4.0.