O efeito do uso de agentes rejuvenescedores encapsulados sobre a autorregeneração de misturas asfálticas.

Abstract

The self-healing phenomenon of asphalt mixtures consists in their capacity to autonomously close microcracks in their body and, consequently, increase the functionality of the surface course. However, in the field, this process is usually not intense enough to match the natural deterioration process. This research assessed a method developed to enhance the natural self-healing of asphalt mixtures: the addition of encapsulated rejuvenators. Soybean oil and waste cooking oil were used as rejuvenators. These oils were encapsulated by ionotropic gelation of alginate in calcium. Three types of capsules were manufactured: Type 1, Type 1 residual, and Type 2 – the first two contain the same oil content, but are composed of soybean oil and waste cooking oil, respectively, and the third is composed of a higher soybean oil content. The capsules were characterized by their chemical composition, size, thermal behavior and resistance to compression. An asphalt mixture was incorporated with the capsules and the effect of these on the void content, indirect tensile strength, water sensitivity, rutting resistance, stiffness and fatigue life of the asphalt mixture was evaluated. Also, the applicability of two methods, based on the indirect tensile and the three-point bending over elastic foundation tests, were investigated to evaluate the self-healing ability of the asphalt mixtures. Different rest periods were used in these methods. The results showed that the capsules have properties that enable their use in asphalt mixtures. The capsules did not affect significantly the volume of voids nor the indirect tensile strength of the mixture. However, its water sensitivity, resilient modulus, resistance to rutting and fatigue life decreased with the capsules’ addition. The indirect tensile-based method presented limitations to evaluate the self-healing. On the other hand, the three-point bending over elastic foundation method gives high self-healing levels for the mixtures with capsules. The maximum healing levels obtained from this method were 138%, 193%, and 147% for the mixture with capsules Type 1, Type 1 residual, and Type 2, respectively. This value was 52% for the mixture without capsules. Therefore, capsules with waste cooking oil stand out for promoting environmental gains as it provides a new use for a waste material. This self-healing intensification system is promising for the development of an autonomous maintenance model for the coating layer of asphalt pavements.