Search

The construction of pavements incorporating reclaimed asphalt pavement (RAP) is taking place around the world, implying the necessity to quantify their net environmental impacts. Life cycle assessment (LCA) is a popular method to analyze the environmental impacts of a product along the whole value chain, providing guidance to practices and technologies from environmental perspectives. However, the LCA research of RAP-modified pavement is seldom performed in Brazil. In addition, as an important source of uncertainties, there is also need of discussion regarding the geographical and technological characteristics in the LCA of pavements. For these motivations, this paper performs a cradle-to-gate LCA to compare the environmental performance of asphalt pavement in Brazil and Switzerland, using the practical rates of RAP use. The functional unit was defined based on the same traffic volume and service life of asphalt pavements, where the mix design and pavement structures follow the standards of the two countries. The results showed that RAP recycling can improve the environmental performance of hot asphalt mixtures in both countries. Binder amount has a high environmental burden and its reduced use by adding RAP has a positive environmental effect. Type of fuel also plays an important role in LCA. In Brazil, it is not recommended to use heavy oils as fuel during the mixing process if other options such as methane gas is available. The results show that the Swiss production of asphalt mixture had lower environmental impact. Nevertheless, a strategic location of material suppliers and mixing plants could lower the transportation distances, improving its environmental performance., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Cold recycled asphalt mixtures (CRAMs) may present a compressive resilient modulus dependent on the stress state. Currently, there is no widespread consensus on a triaxial resilient modulus (TxRM) model for CRAM analysis. A widely accepted TxRM model would favour the analysis of CRAM's layered pavement systems. This paper assessed the adequacy of different TxRM models of CRAM's specimens with different compositions, aggregate gradation and physical characteristics. Based on the literature, three different TxRM models were selected. The models' non-linear estimation was performed through Levenberg–Marquardt algorithm. Model selection analysis was based on residuals square sum root (RSSR) assessment. Ni et al.'s model was found to be the most adequate for CRAM's TxRM modelling based on RSSR analysis. The model selection was done regardless of aggregate gradation, binder type/content, air void content, RAP content, TxRM values range, active filler type and curing time of the tested specimens. [ABSTRACT FROM AUTHOR]

This research evaluated recycled asphalt mixtures (RAMs) for application as wearing course in heavy traffic highways. The main objectives were to investigate the effect of different RAP contents and the effect of a recycling agent (RA) on the mechanical properties of RAMs. Recycled asphalt mixtures with low (10, 20 and 25%) and high (35, 50 and 65%) RAP contents were evaluated. Two of these mixtures (25 and 50% RAP content) were also evaluated after the addition of the RA. The results indicate that conditioning the RAP during the production of RAMs influences the RAP binder activation and the mechanical behaviour of the mixtures. RAMs with high RAP contents presented better resistance to permanent deformation and resulted in satisfactory resistance to fatigue cracking due to the activation of the RAP asphalt binder. Finally, the addition of the RA improved fatigue resistance for higher amounts of RAP without reducing rutting resistance. [ABSTRACT FROM AUTHOR]

Abstract: The wide production of construction and demolition waste and its illegal deposition are serious current problems in Brazil. This research proposes to evaluate the feasibility of using aggregate from recycled construction and demolition waste (RCDW) in pavement applications. A laboratory program was conducted by geotechnical characterization, bearing capacity and repeated load triaxial tests. The results show that the composition and the compactive effort influence on the physical characteristics of the RCDW aggregate. The compaction process has promoted a partial crushing and breakage of RCDW particles, changing the grain-size distribution and increasing the percentage of cubic grains. This physical change contributes to a better densification of the RCDW aggregate and consequently an improvement in bearing capacity, resilient modulus and resistance to permanent deformation. The results have shown that the RCDW aggregate may be utilized as coarse base and sub-base layer for low-volume roads. [Copyright &y& Elsevier]