Evaluation of bituminous mixes in pavement structures interim report IV - Development of surface deformations at statehighway 51 pavement test sites

Abstract

The development of rutting and other deformations in the pavement surface of two sites on a new section of State Highway 51 was monitored for a two year period. Transverse profile tracings, core samples, surface nuclear densities, and stereo-photographs were obtained at these sites. Ruts developed rapidly during the first six months of traffic exposure with maximum rut depths occurring at approximately nine months. Subsequently a gradual reduction in rut depth was observed. Post-construction densification was found in each of the asphalt bound layers at the sites and occurred at both wheelpath and non-wheelpath locations. Increases of up to 12 percent in percent density values of the surface course were observed. Both heave and subsidence of surface elevation points were observed. Surface wear in the wheelpaths was minimal. Based on the analysis procedure used, approximately 50 percent of the maximum rut depth was attributed to densification and the remainder to lateral displacement or instability of the asphalt bound pavement layers.