Great efforts have been made in recent years by the scientific community and the asphalt industry in developing sustainable technologies for the production of asphalt mixtures for road paving applications, pursuing the use of ever higher quantities of recycled materials. In this regard, the challenge is to define the optimal formulation of the mixture which allows the various component materials to be synergistically combined without compromising the performance and durability of the asphalt pavement. In such a context, the experimental study described in this paper aimed to provide a contribution to research by investigating sustainable asphalt mixtures containing 50% reclaimed asphalt pavement (RAP) and polymeric compound composed of 100% recycled plastics. A wide set of mixtures was prepared in a laboratory by employing different dosages of polymeric compound added via the hybrid method at various binder contents. For comparison purposes, an additional set of reference asphalt mixtures containing standard polymer-modified binder (PmB) and virgin aggregate without RAP was prepared and tested. The experimentation focused on the main engineering properties of the asphalt mixtures, including their workability, volumetric properties, and mechanical characteristics. The experimental study involved a preliminary trial phase to establish an appropriate laboratory mixing procedure. The results obtained from the experimentation indicated that recycled waste plastics have good potential for use in asphalt mixtures with high contents of RAP, provided that the quantity of added plastics is adequately balanced.

Sustainability rating systems (SRSs) have emerged as indispensable frameworks for advancing the environmental, social, and economic sustainability of road infrastructure. Despite their growing adoption, their integration as authoritative tools within infrastructure planning and development remains limited. This study provides a comprehensive evaluation of eight leading SRSs—CEEQUAL, Greenroads, GreenLITES, GreenPave, I-LAST, INVEST, BE2ST-in-Highways, and Envision—focusing on their structural frameworks, criteria weightings, adherence to the three pillars of sustainability, and alignment with international benchmarks such as ISO, EN, and ASTM standards. By considering the three pillars of sustainability, the analysis of the eight SRSs reveals a disproportionate focus on environmental well-being (43%) and social well-being (42%), with economic well-being receiving minimal emphasis (15%). Furthermore, this study identifies notable deficiencies in the integration of critical international standards, including ISO, EN, and ASTM, which constrains the comprehensiveness and global applicability of these frameworks. Key findings suggest that the current SRSs inadequately address the principles of a circular economy, risk management, and social equity, highlighting areas for methodological enhancement. This review offers critical insights for researchers, policy makers, and practitioners seeking to refine sustainability rating systems for road infrastructure. By consolidating existing knowledge and proposing methodological advancements, this study contributes to the evolution of SRSs into comprehensive, globally relevant tools for sustainable infrastructure development.

This work focused on the development of a complete laboratory procedure for the rheological characterization of magnetorheological fluids (MRFs) by combining information gained from the literature and practical work performed in the laboratory. The procedure developed involves all the experimental stages for a comprehensive analysis, starting from the sample preparation, choice of the optimal measuring system, definition of the test, and rheometric parameters for the execution of an accurate and reliable analysis. Magnetorheology is a critical approach for studying the field-dependent properties of MRFs; however, measurement errors, often stemming from inappropriate rheometric test parameters, pose significant challenges. Additionally, sedimentation, caused by the large density mismatch between magnetic particles and the carrier fluid, presents a major obstacle that can compromise the analysis. Extensive work was performed for selecting the test parameters as well as defining the most relevant type of analysis to conduct with the defined procedure for the definition of the essential properties of an MRF for braking applications. This work is essential for the development of accurate card material for simulation tools, paving the way for broader utilization of MRFs in cutting-edge technologies.

In recent decades, the international community has recognized the detrimental impact of the construction industry on the environment. In recent years, the use of recycled aggregates has attracted increasing interest as a sustainable and cost-effective solution for the construction and maintenance of road pavements. The life cycle assessment (LCA) represents a valuable methodology for evaluating the environmental sustainability of technologies involving the use of such materials. This study deals with the LCA of alternative solutions for the construction and maintenance of unpaved rural roads. Different scenarios using recycled materials, such as reclaimed asphalt and mineral sludge, are analyzed and compared to a reference solution that employs only virgin aggregates. The environmental sustainability of the proposed alternatives is assessed by considering the global warming potential (GWP), energy requirements, and water consumption. The LCA analysis is performed using SimaPro software (version 9.1.1.7). The obtained results demonstrate that solutions involving the use of recycled materials represent a more sustainable and environmentally friendly option. In particular, a significant reduction in water depletion was found for the alternative scenarios, with savings between 56% and 99%. For GWP and energy, the total savings ranged from approximately 20% to 40%.

The use of recycled aggregates, including waste materials and by-products, has attracted increasing interest in the last decades as a sustainable and cost-effective solution for the construction and maintenance of road pavements, due to the reduction of excavation operations and depletion of natural resources. Life cycle assessment (LCA) represents a valuable methodology for the evaluation of the environmental sustainability of technologies involving the use of such materials. This paper deals with the LCA of an innovative emulsion-based cold recycled mixture specifically conceived to be used as a sustainable solution for the surface finishing of unpaved rural roads. Two scenarios entailing the employment of recycled or virgin materials were analyzed with the assessment of global warming potential (GWP), energy requirement, and water consumption. Results obtained confirmed that the scenario entailing the use of recycled materials represents the most sustainable and environmentally friendly solution.

This paper describes the outcomes of a preliminary study focused on the evaluation of four full-scale pavement sections in which reclaimed asphalt (RAP) was used in partial substitution of virgin aggregates during the production of asphalt mixes. Considered mixes were produced with different RAP percentages and were thereafter laid on site for the formation of asphalt base course layers of pavements in local roads of the State of Qatar. For comparative purposes, two trials included asphalt mixes containing no RAP, and in one case use was made of a rejuvenating agent. Activities carried out for the monitoring of field trials included analysis of component materials, critical observation of production and laying operations, assessment of the most relevant characteristics of produced asphalt mixes, and evaluation of the degree of compaction achieved during construction. Experimental results were of crucial importance for the introduction of RAP-related paving technologies in the State of Qatar, providing a meaningful background to the preparation of the "Ashghal Recycling Manual" issued by Ashghal and of the draft updated version of Qatar Construction Specifications.