Highway trial sections: Performance evaluation of warm mix asphalt and recycled warm mix asphalt

Abstract The present article presents the construction and evaluation of an experimental stretch of highway with environmentally sustainable mixes; warm mixes asphalt and recycled warm mixes asphalt. Six trial sections of an urban highway were constructed with different structural characteristics. Each section was 15 cm thick and 90 m long. The asphalt mixes used for construction of the experimental sections were: reference hot mix asphalt (HMA), warm mix asphalt with natural zeolite (WAMz), warm mix asphalt with Evotherm (WMAe), recycled warm mix asphalt with 20% reclaimed asphalt pavement (RAP) and natural zeolite (WMA R20z), recycled warm mix asphalt with 20% RAP and Evotherm (WMA R20e), and recycled warm mix asphalt with 30% RAP and natural zeolite (WMA R30z). All the asphalt mixes were designed to comply with the design properties required by Chilean specifications, and were fabricated in an asphalt batch plant. The following performance properties were evaluated: stiffness modulus, water susceptibility, permanent deformation, cracking resistance and fatigue behaviour. The ageing of the asphalt binder in each of these asphalt mixes fabricated in the plant was also evaluated by physical and rheological assays of the binder extracted from the mixes. One month after construction of the trial sections, the structural capacity of each section of the experimental stretch was evaluated by falling weight deflectometer (FWD), and the pavement indicators of rutting and the International Roughness Index (IRI) were determined by laser profilometer. Finally, field cores were extracted and tested for stiffness modulus and cracking resistance. The results obtained indicate that the asphalt mixes used presented no major differences in the mechanical properties evaluated, nor in their structural capacity parameters and pavement indices, compared to the control HMA. These mixes present a suitable behaviour, similar to that of a conventional mix, in both their technical and constructive properties, while offering important environmental advantages.