Análise do efeito da adição de agregado poroso, saturado em óleo de soja residual, no rejuvenescimento de camadas porosas de atrito.

Abstract

Floods are common events in large urban centers due to the impermeabilization of natural soil by artificial materials. Integrating stormwater management into urban planning, with the concept of a sponge city, emerges as an alternative to mitigate the impacts of this issue. In this context, the use of open-graded asphalt mixtures in the composition of permeable pavements is a technique that contributes to these solutions. In Brazil, this type of asphalt mixture is used in the production of coatings known as Porous Friction Course (PFC) and has a high percentage of voids, between 18% and 25%, allowing for the drainage of surface water on rainy days. However, premature aging is one of the main issues encountered in PFC structures, due to their high void volume. On the other hand, the use of rejuvenating agents proves to be an attractive alternative in reversing asphalt binder aging. The objective of this research was to analyze the rejuvenation of PFCs through the addition of Porous Aggregate Saturated with Residual Soybean Oil (PASRSO). For this purpose, chemical and rheological analyses of the binders, extracted and recovered, from three variations of PFCs were conducted: two with the addition of PASRSO, resulting in 0.5% and 0.7% residual soybean oil relative to the weight of the asphalt mixture, and one pure mixture. Additionally, the mechanical and functional behavior of these mixtures was examined, which were subjected to aging and aging/cyclic loading protocols. The aging protocol included a combination of short-term and long-term aging, where compacted specimens were kept in a conventional oven and then subjected to simulated rain, considering that the parameters that most influence the aging of PFCs are temperature and humidity. The cyclic loading stage was added to assess potential variations in oil diffusion within the mixture under traffic conditions. Chemical analysis was conducted to determine oxidation levels and to qualitatively and/or semi-quantitatively identify the presence of organic additive in the binders. Regarding rheological properties, these were assessed through Performance Grade (PG), Multiple Stress Creep Recovery (MSCR), master curve, and Linear Amplitude Sweep (LAS) tests. In terms of functionality and mechanical properties, the analysis was based on rutting tests, void volume, communicating voids, draining behavior, permeability, Cantabro abrasion loss, tensile strength by diametral compression, moisture-induced damage, and resilience modulus. From the results, it was observed that the addition of oil at 0.5% and 0.7% showed similar trends, with no statistically significant differences. However, the 0.5% content showed slightly better performance, with greater reduction in oxidation indices under all analyzed conditions and less impact on RT after aging. Overall, porous aggregate proved feasible as a carrier for rejuvenating agents, offering a solution to rejuvenate porous friction course layers without significantly impacting the functional and volumetric properties of the mixture. However, the methods of binder extraction and recovery did not consistently restore the rheological properties of aged binders, making it difficult to confirm the effective action of the oil.