Optimization of aggregates skeleton using laser-scanning technology and discrete element method

Abstract

The skeletonof aggregates hasasignificanteffecton the performance of porous asphalt mixtures. In this study, laser-scanning technology was utilized to obtain two-dimensional digital images of four groups of aggregates with different particlesizes. Digitalimage processing technology was used to obtain the basic dimensional indicessuch asarea, perimeter, and equivalent ellipse of aggregate particles. Based ontheseindices, the morphological characteristics of theaggregates,including aspect, roundness, andangularity,were evaluated.Then,virtual uniaxial penetration tests were simulated via the discrete element method (DEM) and verified by the results of laboratory uniaxial penetration tests. On this basis, the visualization design of the optimal main skeleton for the porous asphalt mixture was conducted. Results show that the shapes of the aggregateswereclose to cubes. Aggregates with sizes greater than 4.75 mmhada more significant structural effect on the skeleton than those with sizes smaller than 2.36 mm. Coarse aggregatescouldform a stable skeleton by interlocking with each other, whereas the skeleton formed by fine aggregateswasfragile. Coarse aggregates primarilywithstoodthe external load while fine aggregates primarilylimitedthe displacement of coarse aggregates. The optimal main skeleton designed by combining the DEM with the laser-scanning technology can provide new possibilities for the gradation design of porous asphaltmixtures.