Moisture damage resistance of hot-mix asphalt made with recycled concrete aggregates and crumb rubber

- Hot-mix asphalt (HMA) made with recycled concrete aggregate (RCA) has been analysed.
- Water resistance evaluation of HMA made with 0%, 35% and 42% of RCA was conducted.
- Mixtures were manufactured with conventional B35/50 penetration grade bitumen.
- The use of crumb rubber as bitumen modifier does not improve water resistance.
- Reversibility of moisture damage resistance was demonstrated in this research.

To guarantee sustainable construction, we investigated the reuse of construction and demolition waste (CDW) as recycled concrete aggregate (RCA) for the manufacture of hot-mix asphalt (HMA) in place of natural aggregates. The use of waste tire rubber as a bitumen modifier could be a means of improving the water resistance of these mixtures. In this investigation, moisture damage resistance of HMA for binder course, type AC 22 bin S, was analysed. Percentages of 0% (control mixture), 35% and 42% RCA were used in place of natural aggregates. Two types of bitumen have also been used: a conventional B35/50 penetration grade bitumen and BC35/50, a crumb rubber modified bitumen. Volumetric properties and water resistance were determined by means of indirect tensile tests. The results indicate that contrary to expectations, mixtures made with BC35/50 do not display better water resistance than mixtures made with B35/50. Nevertheless, a mixture made with B35/50 or BC35/50 does comply with Spanish requirements. Additionally, reversibility of moisture damage resistance was clearly demonstrated in this research. This research may help to better understand the performance of HMA made with RCA and the drawbacks of using waste tire rubber as a bitumen modifier.