Abstract
The most usual asphalt mix applied for thin overlays on Spanish roads is produced with a gap-graded combination of aggregates and a polymer-modified binder. Nevertheless, reflective cracking usually affects the overlay so that the surface of the pavement soon begins to reveal a network of cracks. The brittleness and aging of asphalt mixes at low temperatures encourage the appearance and progress of these cracks. Asphalt mixes incorporating rubber from discarded tires are believed to control reflective cracking well. This paper presents a study performed on five gap-graded asphalt mixes, three containing rubber from tire waste. Every mix was tested at two stages of aging in accordance with the laboratory-accelerated aging processes proposed by SHRP. Dynamic moduli at several temperatures, ranging from −15°C to 40°C, and the fatigue life of each mix at 20°C were measured. The results are provided to help researchers build realistic models for studying reflective cracking as a function of the actual characteristics of the materials. The results show that the tire rubber, especially when incorporated by the wet process, enhances the fatigue life of the mixes. The thermal sensitivity of the mix decreases as the content of rubber arises, regardless of whether the rubber has been incorporated by the wet or the dry process. In addition, the paper reports the difficulties with the SHRP accelerated aging processes and raises some doubts about these aging processes when applied to rubberized asphalt mixes.
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