DEM simulation of field asphalt compaction

Abstract

Asphalt mixtures compaction, despite its importance to asphalt layers performance, is one of the pavement issues with less scientific knowledge. All over the world, road administrations publish varied guidelines and roller manufacturers produce wide-ranging characteristics machines. Only with a tool that justifies what occurs during the compaction process one may understand its behaviour. In the present paper, a computer simulation based on the Distinct Element Method (DEM) is adopted to study this matter. Asphalt mixtures are modelled as an assemblage of circular rigid particles that interact with each other at soft contact points based on DEM, using Itasca-PFC2D software. The validation of the numerical model to laboratorial static compaction has been carried out in previous studies. In this paper it is discussed the attempt to model real roller compaction.A field compaction test was carried out to acquire the necessary data for the model. An asphalt layer (AC 0/16 mm) with approximately 50 m long, 2.5 m wide and 70 mm thick, before the roller compaction, was divided in two parts for each compaction mode. One was compacted with the roller (HAMM HD75) in static mode and the other in the vibratory mode. The temperatures, inside and superficial, the thickness of the layer and the drum vibrations were monitorized during the roller compaction. For the loading method it was used an inverse modelling scheme, the displacements are prescribed instead of the forces and the simulation results are the force evolution, the assembly stresses and the thickness reduction. Results agree with other related matter published work, (Huerne, 2004). It is shown that the model is reasonably successful and that it provides a good insight in the asphalt compaction behaviour.