Ravelling Resistance of a Warm Porous Asphalt Containing Reclaimed Asphalt

Porous asphalt (PA) is commonly used in the wearing courses of Italian motorways due to its effectiveness in promoting rainwater drainage and enhancing skid resistance under wet conditions. However, PA is particularly susceptible to ravelling, a surface degradation process primarily caused by tire–pavement interaction during vehicles’ movements. This study evaluates the ravelling resistance of warm PA mixtures containing 15% of reclaimed asphalt (RA) and two different additives, tested under both dry and wet conditions. The assessment was performed using the conventional Cantabro test and the Darmstadt Scuffing Device (DSD), which simulates steering, acceleration, and braking forces under wet conditions. Laboratory-produced mixtures were designed to compare hot and warm mix asphalt technologies and to assess the effect of fluxing- and surfactant-based chemical additives. The results show that conventional PA mixtures produced at low temperature perform poorly, while warm mixtures with chemical additives exhibit ravelling resistance comparable to that conventional PA mixture. In particular, the surfactant-based additive containing amine and carbonyl functional groups was found to enhance both ravelling resistance of warm PA mixtures.