Case Study of a Composite Layer with Large-Stone Asphalt Mixture for Heavy-Traffic Highways

Abstract

The large-stone asphalt mixture is a promising approach to improve rutting resistance of roads under very heavy traffic. This paper describes the rehabilitation of two test sections in Brazil using a composite of dense graded asphalt mixtures with typical (9.5 or 19 mm) and large-stone (32 mm) nominal maximum aggregate size to decrease rutting while simultaneously preserving the functional surface qualities of the pavement. The asphalt mixtures used in this study were characterized for their linear viscoelastic properties using dynamic modulus and rutting resistance using the French wheel tracking test. The rehabilitated pavement was monitored over a period of 2 years and demonstrated minimal rutting. This was in contrast to the 12–15 mm rutting that occurred over just 1 year prior to the rehabilitation when only 9.5- and 12.5-mm size dense graded mixture was used on the surface with different asphalt binders. This study also demonstrates that this difference in field performance was not reflected when using viscoelastic layered analysis of the pavement structure, which is a recognized limitation when damage analysis is not considered.