Highly Modified Bitumen for Prevention of Winter Damage in OGFCs

Abstract

Porous asphalt pavements with a large percentage of air voids such as open graded friction courses (OGFC) have been built across the United States since the 1950s. The OGFCs have several benefits such as a higher degree of friction and permeability providing drainage of rain water from the surface of the pavement. However, only a few cold winter nights can cause years' worth of raveling damage to a road when stresses due to traffic loads and day to night temperature variations reach the binder's breaking point. Delft University of Technology developed a finite element model, the Lifetime Optimization Tool (LOT), to study this phenomenon by predicting asphalt mix response from asphalt mortar properties. Mortars of long-lasting porous asphalt roads were compared with those from early-failure roads. The study concluded that two factors are critical to prevent winter damage: ≤ Limited binder stiffness at low temperature, particularly after aging ≤ Binder stress relaxation at these low temperatures. In a search for improved binder performance, four different highly modified binders were produced by Kraton Polymers Research B.V. Master curves were developed on laboratory-aged binders for viscoelastic properties, and the mortar performance was evaluated at different temperatures and temperature fluctuations using the protocol of the LOT model. The results were compared with literature data of the existing road sections and showed a dramatic improvement in raveling resistance. The SBS polymer-modified binders demonstrated exceptional performance in the winter and at least an equally good performance under summer conditions.