Effect of WMA Additives on Asphalt Ageing - Case Study

One of the current main trends in road construction is striving to ensure greater durability of asphalt surfaces. The observed increase in road traffic, especially the increase in heavy goods vehicles in the overall traffic structure, as well as the impact of adverse weather conditions such as prolonged high summer temperatures and low winter temperatures, and the impact of rain and snowfall contribute to reducing the durability of asphalt surfaces. An important material factor that also affects the reduction of the durability of asphalt surfaces is the ageing of asphalt. In the process of rolling the mineral-asphalt mixture, it is affected by elevated temperatures ranging from 165oC to even 200oC, which contributes to the loss of the adhesive-elastic properties of the asphalt. This process intensifies during the exfoliation of the asphalt surface, which is affected by solar radiation and atmospheric waste. To counteract asphalt ageing, work is conducted to modify it using, for example, polymers and various chemical additives, as well as the use of technologies in which asphalt can be used to produce mineral-asphalt mixture at a reduced temperature. The most effective solutions of this type include the technology of water-foamed asphalt. To limit the ageing of 50/70 asphalt in tests, synthetic wax was used as an additive dosed at 1.0%, 1.5%, 2.0% and 2.5% by weight, and a surfactant was used at 0.2%, 0.4% and 0.6% by weight in relation to the asphalt. Studies on the impact of additives on road asphalt 50/70 before and after the water foaming process have been conducted. The change in basic asphalt parameters after RTFOT technological ageing was analysed. A significant impact of additives on the ageing process of 50/70 asphalt has been observed. Synthetic wax has a more intense effect on asphalt 50/70, it slows down the aging of the binder more than the use of a surface-active agent. On the other hand, the use of additives to asphalt 50/70 before its foaming with water has an even more beneficial effect on slowing down the intensity of binder ageing. In summary, the use of synthetic wax and a surfactant as additives to asphalt treated with foamed water will not only help limit the ageing of the binder and ensure the durability of the asphalt surface, but will also play a significant role in producing more environmentally friendly mineral asphalt mixes as a result of lowering the technological temperatures of their production process.