Avaliação de diferentes tecnologias de misturas asfálticas mornas com a incorporação de elevadas quantidades de material fresado.

Abstract

Warm Mix Asphalt (WMA) technologies and the Reclaimed Asphalt Pavement (RAP) have received much attention in recent years due to their economic and environmental benefits. WMA can be machined and compacted at lower temperatures than traditional hot-mix temperatures providing reduced energy consumption and CO2 emissions. The use of RAP can replace a certain proportion of asphalt binder and virgin aggregates needed for the construction of new asphalt sidewalks, which allows for the environmentally appropriate disposal of RAP and reduction of production costs. In the present research, the effects of adding three commercially available technologies for the manufacture of WMA (sunflower oil, WarmGrip®, and natural zeolite) with different percentages of milled material (30 and 70% of RAP) were evaluated as a way to enable the recycling of RAP at higher rates of participation in the final mix. The binders derived from the RAP and the new binders modified by the WMA additives were characterized by their chemical composition and through rheological tests. The degree of activation of the RAP binder was also analyzed to determine the minimum amount of RAP binder that can be considered active in the formulation of a new asphalt mix containing milled materials. The additives were incorporated into the recycled asphalt mixtures and the effects of this addition on the indirect tensile strength, water sensitivity, resilient modulus, rutting resistance, fatigue life, and dynamic modulus were evaluated. The results showed that recycled asphalt mixtures should not be designed with the assumption of full binder activation of RAP. Raising the RAP content increased the stiffness of the mixtures and consequently provided growth rutting resistance. However, sunflower oil and natural zeolite showed rejuvenating properties and acted by decreasing the stiffness of these mixtures. Warm recycled mixtures exhibited an increased number of cycles to failure in the fatigue test and increased adhesion and cohesion, verified by the water sensitivity test, with emphasis on the recycled mixtures with the WarmGrip modified binders. Therefore, the warm recycled mixtures allowed the incorporation of higher amounts of RAP when compared to conventional hot recycled asphalt mixtures, especially the warm recycled mixtures with up to 30% of RAP.