Production of hot-mix asphalt with PMB: Compactability and mechanical behaviour characterization

Abstract

The traditional approach used to select production (mixing and compaction) temperatures for hot-mix asphalts (HMA) with polymer modified bitumens (PMB) often lead to extremely high temperatures, which increase energy consumption and may cause bitumen-polymer bond degradation. Moreover, field experience indicates that lower temperatures can be used without compromising aggregate coating with bitumen and on-site compaction. This paper presents a lab study aiming to assess the influence of production temperatures in the on-site paving operations and the in-service performance of asphalt pavements. An AC 14 Surf PMB 45/80-65 (EN 13108-1) was produced and compacted at three different mixing-compaction temperatures groups, based on the suppliers’ recommendation and the temperatures determined with the traditional (Superpave) and the high-shear rate viscosity (HSRV-E) methods. The results showed an important effect of the production temperatures in the asphalt behaviour. Minimum compaction resistance value was obtained with the Superpave temperatures while HSRV-E produced the highest resistance. The water sensitivity test values and the rutting resistance values were very similar for the three temperatures groups. Independently of the test frequency, the stiffness modulus was always higher for the HMA produced at the suppliers’ recommended temperatures. The resistance to fatigue is very similar for the Superpave and HSRV-E temperatures, and higher than with the suppliers’ recommended temperatures. Fatigue resistance was not affected by the use of a higher mixing temperature, recommended by the Superpave method. The best performance was not obtained with any single temperatures group tested and the results show that both mixing and compaction temperatures are very important for the HMA behaviour.