Three-Dimensional Simulation of Aggregate and Asphalt Mixture Using Parameterized Shape and Size Gradation

Abstract

Aggregate occupies at least three-quarters of the volume of asphalt mixture and can significantly affect the performance of pavement. The geometrical morphology influences the slippage and interlock among aggregates for resisting and distributing applied loads. In recent years, the discrete element method (DEM) has been employed for simulation of asphalt mixture structure. This paper introduces an approach for simulation of aggregate and asphalt mixture using parameterized shape and size gradation. Both plane geometry factor (PGF) and section aspect ratio (SAR) were employed to describe the 3D geometric characteristics of aggregates. A numerical technique of aggregate models was implemented with probabilistic parameters depending on statistical results of PGFs and SARs. Therefore, the 3D numerical model of asphalt mixtures was assembled with three different components, which is validated by uniaxial compression test via comparison with that of the laboratory result. It was found that the PGF and SAR are appropriate to describe the three-dimensional features of aggregate shapes, due to the fact that a simplified space object can be described by a 2D graphical projection and a vector scalar corresponding to the space vector. Probability distribution curves of PGFs and SARs between coarse aggregates are in concordance with the Gauss-type function, since their correlation coefficients are all greater than 95%. It was verified that the developed clumping algorithm of aggregates was reasonable with the shapes and size gradation. Based on the parallel-bond model and the Burger's model, the results of virtual tests are in good agreement with those of laboratory uniaxial tests. It is shown that the angularity (PGF) of aggregates has a beneficial effect on the strength and stability while the flat-elongated feature (SAR) has a negative effect on those of asphalt mixtures.

The Evaluation Method of Particle Clustering Phenomena in RAP

“…It is suggested that the nonlinear viscoelastic response of RAP mixtures at high temperatures should be considered in the future investigations [31]. The particle packing ability before and after crushing for different types of RAP should be considered to provide a better understanding of the effect of particle clustering on the overall performance of the mixture in the future study [32][33][34].…”

Performance Evaluation of Recycled Asphalt Pavement Materials and Cold Recycling Mixtures Designed with Vibratory Compaction Method

“…Due to the existence of old asphalt in the old materials, the asphalt cannot be dried at a high temperature, which will soften and loosen the asphalt in the RAP materials and affect its gradation. In order to minimize the grading variability of RAP materials, firstly, RAP materials were screened into three levels, with the 16 mm and 2.36 mm sieve pores as the boundary, and the sieved third-grade RAP were sampled according to the 4-point method, drying in a ventilation oven at 40 • C to a constant weight, and sieving according to the specification requirements to obtain grading distribution [23,24].…”

Evolution Characteristics of the Cracks in the Completely Disintegrated Carbonaceous Mudstone Subjected to Cyclic Wetting and Drying

“…e methods for crack measurement are also increasingly diverse. For instance, the photography, computed tomography (CT), ultrasonic testing (UT), and conductance method (CM) have widely been applied to observe the soil structure including cracks in the literature [22][23][24][25]. However, there are very few instruments that allow the continuous, nondestructive observation of the development of cracks during wetting and drying tests.…”