Bethania Machado Correa

1. Reclaimed Asphalt Pavement (RAP) is obtained by milling asphalt paving layers at the end of their service life, which are established within limiting criteria for damage due to permanent deforma...

Lime stabilization is a sustainable technique due to its use of local materials, increased durability, reduced maintenance, and improved resistance to water action. This paper examines the impact of lime stabilization on the mechanical, microscopic, and mineralogical properties of a tropical soil. Two types of lime, calcitic and dolomitic, were tested at 3% and 5% by weight. Compressive, indirect tensile and flexural test results and statistical analysis revealed that calcitic lime mixtures had higher strength and stiffness, whereas dolomitic lime mixtures exhibited greater deformability with higher tensile strain at break. Scanning electron microscopy indicated that the soil’s porous matrix closed within 7 days for both lime types due to flocculation, with increased matrix interlocking over time. The calcitic lime mixture developed a more closed matrix compared to the dolomitic lime, which showed weaker cementing. X-ray diffraction analysis indicated higher consumption of clay minerals and a notable reduction in calcium hydroxide peaks in the lime-treated soils. The study concludes that calcitic lime provides better pavement performance for stabilizing the soil, enhancing its engineering properties while also being sustainable by reducing the need for raw material extraction and improving resilience to climate-related issues such as floods.

This study aims to evaluate the fatigue phenomenon in recycled hot asphalt mixture for an asphalt surface layer. Eight mixtures were evaluated in the laboratory, and the samples were divided into two major groups: four mixtures containing neat binder and RAP from source 1 (RAP with neat binder) and four mixtures containing SBS-modified binder and RAP from source 2 (RAP with SBS-modified binder). The levels of RAP incorporation were 0%, 10%, 20%, and 30% in relation to the total weight of the mixtures. The mixtures followed the Marshall mix design methodology. The results indicate that mixtures with polymer-modified binder presented better performance, whereas the addition of RAP slightly decreased the resistance to fatigue cracking. In terms of economic analysis, the use of RAP, for all cases, leads to a reduction in production costs due to the reduction of the binder and aggregate added, with savings of up to 14.1% in the case of 30% of RAP for the SBS binder. When evaluating the economic impact of inserting RAP and its relationship with fatigue performance in the long term, it can be observed that the type of binder added impacts the results: mixtures with SBS binder present economic gains within acceptable quality parameters up to 30% RAP insertion; for mixtures with neat binder, the percentage of up to 10% RAP is advantageous.

Com o objetivo de avaliar tecnologias e práticas mais sustentáveis para a área de pavimentação, estudou-se o comportamento de misturas asfálticas recicladas mornas, utilizando ligantes convencional CAP 50/70 e modificado por polímero CAM 60/85-E. Foram ensaiadas quatro misturas asfálticas por ligante: convencional à quente, morna (sem RAP) e morna com 25% e 50% de RAP (em substituição à massa total de agregados virgens). As amostras foram dosadas pela metodologia Superpave e avaliadas quanto às propriedades de resistência, deformabilidade, adesão e coesão. As misturas mornas e convencionais apresentaram comportamento equivalente e o uso de ligante modificado elevou o desempenho das amostras. Houve uma melhora significativa nas propriedades das misturas com o uso de RAP, ressaltando-se o expressivo aumento de Flow Number e os resultados positivos de adesão e coesão, provavelmente, em decorrência do RAP apresentar ligante residual modificado com polímero.