Incorporation of chromium-tanned leather residue to asphalt micro-surface layer

A study on the incorporation of chromium-tanned leather residue to the cold asphalt micro-surface layer was performed using the dry mix process. Laboratory designs for asphalt micro-surface were performed according to the methods specified by NBR (National Brazilian Standards), with additions of 0.3%, 0.5% and 0.7% residue without adding fiber to the asphalt mass. According to the technical work specification DNER-ES 389/1999, the MRA was experimentally applied to a 320-m stretch of Hélio M. Salles Highway (215 km) in the town of São Sebastião da Grama – in the state of São Paulo, Brazil. The results showed that the incorporation of 0.3% of leather sawdust increased the engineering properties of asphalt mixtures and minimized the cracking of pavement surface layer due to the fiber incorporation in the asphalt micro-surface.