Amanda Gibney

Laboratory Study of Resistance of Bituminous Overlays to Reflective Cracking

Recent increases in traffic volumes in Ireland have led to severe loadings on pavements, which are showing some signs of distress, primarily in the form of rutting and reflective cracking of overlays. The particularly short life of bituminous overlays on concrete pavements has prompted an examination of both the materials currently in use and possible alternative materials. The research program undertaken at University College Dublin to assess the resistance to reflective cracking of a variety of bituminous mixtures currently in use in Ireland is described. Laboratory-prepared slabs were provided with variable support conditions and subjected to loading through a reciprocating wheel. This setup allowed a variety of mixtures and binders, including polymer-modified binders, to be compared under accelerated test conditions that simulated long-term field performance. The setups used to examine the resistance to reflective cracking are detailed, and the results obtained ranking both mixture and binder performance are summarized. In addition, standard wheel-tracking tests were carried out on the mixtures used to determine their resistance to permanent deformation.