Recycled porous asphalt concretes: pros and contras

Porous European Mixes (PEMs) have been recognized as one of the most adequate solutions for pursuing asphalt pavement sustainability. In fact, apart from the well-known advantages in terms of skid resistance improvement in wet conditions, porous mixes are also useful for traffic noise reduction. Several studies show that the percentage of noise reduction for PEMs can reach a value of around 20% if compared with a traditional asphalt mix. Nevertheless, few researches still deal with the identification of mix design solutions for noise reduction optimization. Another important issue for producing an eco-friendly asphalt concrete is related to the amount of RAP (Reclaimed Asphalt Pavement) used inside the mix. In the light of the above, the objectives of the study described in this paper are confined into the assessment of surface and acoustic performance of recycled porous asphalt concretes (PEMs). Acoustic properties were measured according to the ISO10534-2. Also surface texture was investigated according to the standards ISO 13473-1; ISO/CD TS 13473-4; ISO 13473-3. Moreover, the relationship between acoustic absorption coefficients and pavement surface performance was studied as a function of the degree of compaction of laboratory asphalt mixes (by gyratory compactor). Finally, recycled PEMs performance was compared with the one of a reference PEMS produced by virgin porous mix. Results show that both drainability and texture depth are well correlated with several parameters associated with acoustic absorption spectra for both recycled and virgin mixes, regardless of the degree of compaction. Results can benefit both practitioners and researchers.