Assessment of the effect of the use of highly-modified binder on the viscoelastic and functional properties of bituminous mixtures illustrated with the example of asphalt concrete for the binder course

Abstract

Polymer-modified binders (PMB) have been known and used for many years to increase asphalt pavement durability. The most commonly used polymer is the SBS elastomer (styrene–butadienestyrene). Its content in the classic polymer-modified binder ranges from 2 to 4% m/m (by weight). In such a case, it fills up to 40% of the binder’s volume to form a polymer network. In highly-modified asphalt binder (HiMA), the amount of polymer is twice as large and reaches a level of 7–8% m/m, which means that the polymer phase in binder volume dominates the asphalt phase. The extensive continuous polymer network additionally causes significant changes in the properties of the binder. Highly-modified binders have been available on the Polish market for several years. This article assesses the impact of the use of highly-modified binder on the properties of asphalt concrete for the binder course. As reference, a test programme also included three other bituminous binders used in Poland. The assessment took into account the basic and functional properties of mixtures over a wide temperature range, as well as failure mechanisms most relevant for the binder course. Testing included resistance to water, complex modulus, resistance to permanent deformations, resistance to low temperature cracking and tensile strength. Other important characteristics such as fatigue resistance have been tested for mixes for the base course, which is outside the scope of this article. Test results were subject to analysis, which indicated that the use of HiMA for the asphalt concrete mixture significantly alters the viscoelastic properties and has a positive effect on strength and functional properties of the mixture. Analyses were carried out to show distinct relationships between viscoelastic characteristics and other properties.