Estudo de técnicas de estabilização de solos e reciclagem asfáltica aplicadas em uma rodovia federal não pavimentada do estado da Bahia

Abstract

Unpaved roads are essential for the economic and social advancement of societies, as they connect rural areas to markets, healthcare, and educational opportunities. In many developing countries, a substantial portion of the road network consists of unpaved roads. Given limited resources for transportation infrastructure and increasing environmental restrictions regarding gravel quarrying, a focused approach to unpaved roads is not only necessary but also aligns with modern practices worldwide that aim for increasingly sustainable and technically appropriate solutions. In this context, the present research was designed to evaluate the performance of different soil stabilization techniques used in the construction of an experimental segment of a federal unpaved road in the state of Bahia, Brazil, by monitoring structural and functional conditions. The use of locally available materials was studied, as well as their chemical stabilization using lime and cement, and the addition of reclaimed asphalt pavement (RAP). The study was conducted on BR­030 in the municipality of Boa Nova­BA, over a 600­meter segment with five solutions and one control section. The raw materials used included the gravel from the current primary surfacing (RP), Portland cement, hydrated lime, and RAP. In the laboratory phase, the influence of the binder content, RAP content, moisture content, molding porosity, and curing time was evaluated on compaction behavior, resilient and permanent deformation, durability, and microstructure of the stabilized RP. After 28 days of curing, the RP + 1% Cement 1% Lime mixture showed the greatest stiffness gain, with a 554.13% increase in resilient modulus (MR) compared to pure RP, along with the highest reduction in permanent deformation (PD) at 61.83%. Mixtures with 2% cement and 2% lime also performed well, with MR increases of 435.65% and 257.15%, respectively. The combination with 0.5% of each additive yielded a gain of 137.38%. Regarding RAP usage, the 50% RP + 50% RAP mixture showed a good balance, with an average MR of 222.06 MPa (+18.71%) and a smaller PD increase of 39.74% compared to pure RP. On the other hand, the 75% RP + 25% RAP formulation had the lowest stiffness gain (6.48%) and the highest increase in PD (106.58%), indicating poorer performance. In the experimental segment, however, the control section and the section treated with lime and cement jointly showed the best field performance. The section with RAP and cement showed the highest disaggregation—about 9 times greater than the control— along with more dust generation and corrugation. Sections with RAP recorded up to 10% pothole area during rainy periods. Based on these results, it is concluded that for pavement structures with high bearing capacity, like the one observed at the site, a promising solution would be the construction of a waterproof surface layer for longerlasting performance.