A complete laboratory assessment of crumb rubber porous asphalt

- Use of fine crumb rubber by dry process in porous asphalt.
- Drain-down test comparison between fine crumb rubber and fibres in porous asphalt.
- Higher bitumen/aggregate affinity of crumb rubber mixtures comparing to fibres mixtures.
- The use of crumb rubber improved the thermal and water sensitivity behaviour of porous asphalt.
- Higher ravelling resistance by means of Cantabro particle loss results for rubberized porous asphalt.

Besides the many advantages of porous asphalt (PA), the permanent deformation resistance, fatigue strength, stripping and moisture susceptibility are not as good as for dense graded mixtures. In this research, the effectiveness of adding crumb rubber (CR) by dry method to PA mixtures was assessed. Rubberized porous asphalt (RPA) mixtures manufactured incorporating CR into SBS modified asphalt concrete were produced and compared with a control mixture by means of Indirect Tensile Strength (ITS), Indirect Tensile Stiffness Modulus (ITSM), moisture susceptibility, permeability, Cantabro, rolling bottle, draindown and creep tests. Results proved that although the application of CR reduces the vertical permeability and permanent deformation resistance, it improves the bitumen/aggregate affinity and it controls the draindown rate without adding fibres. On the other hand, the use of CR decreased the ITSM value at low temperature, which represents a lower susceptibility to thermal cracking. Other complementary test results in this research support the effectiveness of RPA mixtures.