The stabilization of asphalt pavement bases with granular soil and aggregates emulsified with asphalt is a widely used technique in road construction and maintenance. It aims to improve the mechanical properties and durability of the lower pavement layers. Currently, there is no consensus on the most suitable method for designing emulsified granular aggregates with reclaimed asphalt pavement (RAP), as it is very complex. Therefore, the methodology is generally based on compliance with one or more volumetric or mechanical parameters established in the highway regulations for conventional asphalt mixtures, which does not guarantee the optimization and characterization of the recycled mixture in the base course. In this study, granular mixtures were developed, including five with emulsion and one emulsion-free as a control mix. Granular RAP mixes were designed in this study, including five with emulsion and one emulsion-free as a control mix. The five mixes ranged from 1% to 5% emulsion and were characterized by multi-stage triaxial tests with repeated load resilient modulus (RM) and permanent deformation (PD) to evaluate their mechanical behavior. The results showed that the mixes had RM values between 350 and 500 MPa, consistent with literature values. However, they showed similar levels of accumulated deformation to the control mix without RAP emulsion. The sample with 1 % RAP emulsion exhibited a satisfactory RM value and better performance in PD than the control mix (5 mm) and showed accumulated PD values of up to 4 mm. In contrast, the other samples exhibited deformations of up to 6 mm. In this study, the multi-stagge triaxial RM and PD tests were found to be an effective predictive method for characterizing the behavior of RAP materials in base courses, regardless of the types of admixtures contained. Multi-stage resilient modulus and PD tests can be considered as a predictive method for the behavior of milled material in base courses. They were able to provide initial data for interpreting the behavior of ETB mixtures.

This study examined the mechanical behavior characteristics of cold recycled emulsified asphalt bases with RAP 76% and emulsified asphalt 3%, in different cure time, i.e., 0, 7, 14 and 28 days and evaluated in terms of the resilient modulus (RM) and permanent deformation (PD) based on repeated load triaxial tests. The results demonstrated that in the first 7 days, the RM increased by 80% compared to the freshly compacted material and after this period, the subsequent increases were not as significant, ranging, from 10.9% to 19.4%, that shows that initical cure time significantly influences the RM behavior of the mixtures. However, the mixtures showed considerable permanent deformations, even after 28 days of curing. This indicates that the use of asphalt emulsion, with prolonged curing, improves the mechanical properties of the mixture but does not entirely resolve the issue of permanent deformation in cold reclaimed asphalt mixture (CRAM). The plastic deformation behavior observed in the triaxial tests must be taken into account when designing pavements containing RAP and asphalt emulsion.

Research on road construction has evolved and advanced. Environmental sustainability considerations are now an integral part of the specific focus of these infrastructure projects. This study investigated the feasibility of recycling on iron ore reject through cost-effective pavement techniques, demonstrating significant improvements in the performance of stabilized mixtures with the addition of anti-dust treatment. The mineralogical and chemical analysis of the reject, coupled with the conducted priming tests (LWT and WTAT), highlighted the effectiveness and promising application of these materials in construction. Under a load of 33 kg, the anti-dust-treated mixture showed a deformation of 5.3 mm, compared to 7.76 mm for the stabilized reject–emulsion mixture. Similar improvements were observed in reject–soil–emulsion mixtures, with a sinking of 4.16 mm for anti-dust-treated specimens compared to 6.99 mm for stabilized mixtures. The results of the WTAT test corroborated the effectiveness of the layer formed by the anti-dust treatment; in all cases, the mass loss was less than 2%. These findings have significant implications for sustainability in construction, contributing to environmental conservation and resource efficiency.

Recent advancements in railway construction have emphasized environmental sustainability, integrating considerations of environmental impact into the planning and execution of infrastructure projects to reduce costs and mitigate adverse effects. This study investigates the use of steel slag as a sustainable alternative for railway ballast, grounded in shakedown theory. The characterization of the aggregates was performed in accordance with NBR 5564 and AREMA standards, confirming that the material meets most requirements. The mechanical behavior of the ballast was analyzed under cyclic loading conditions, assessing permanent deformation and the material’s ability to achieve stability (shakedown). Triaxial tests with repeated loading simulated real railway conditions, applying vertical stresses up to 600 kPa and confining pressures ranging from 35 to 200 kPa. The results indicate that steel slag aggregates exhibited promising performance, with seven specimens achieving stable deformation levels, characterized by residual deformations of less than 2.5 mm. Notably, these specimens approached deformations on the order of ${10}^{-7}$, indicating stability under cyclic loading. Furthermore, a comparative analysis of shakedown criteria proposed by various authors revealed variations in limits for granular materials, enhancing the understanding of steel slag aggregate behavior. The experimental results were validated through numerical simulations conducted with Systrain software 2.0, which simulated a loading condition of 32.5 tons per axle, confirming the observations with maximum principal stresses ranging from 166 to 184 kPa in the ballast. The analysis showed that steel slag aggregates can withstand stress levels higher than those of granodiorite, reinforcing their viability as a sustainable alternative for railway ballast.

Ferronickel slag (FNS) is a byproduct produced during ferronickel alloy manufacturing, primarily used in the manufacturing of stainless steel and iron alloys. This material is produced by cooling molten slag with water or air, posing significant disposal challenges, as improper storage in industrial yards can lead to environmental contamination. This study investigates the chemical and mineralogical characteristics of reduction ferronickel slag (RFNS) and its potential use as an alternative aggregate in hot mix asphalt (HMA). The research is based on the practical application of HMA containing RFNS in an experimental area, specifically the parking lot used by buses transporting employees of Anglo American, located at the Codemin Industrial Unit in Niquelândia, Goiás, Central Brazil. Chemical analysis revealed that RFNS primarily consists of MgO, Fe₂O₃, and SiO₂, which are elements with minimal environmental impact. The lack of significant calcium content minimizes concerns about expansion issues commonly associated with calcium-rich slags. The X-ray diffractogram indicates a predominantly crystalline structure with minerals like Laihunite and Magnetite, which enhances wear and abrasion resistance. HMA containing 40% RFNS was tested using the Marshall methodology, and a small experimental area was subsequently constructed. The HMA containing RFNS met regulatory specifications and technological controls, achieving an average resilient modulus value of 6323 MPa. Visual inspections conducted four years later confirmed that the pavement remained in excellent condition, validating RFNS as a durable and effective alternative aggregate for asphalt mixtures. The successful application of RFNS not only demonstrates its potential for local road paving near industrial areas but also underscores the importance of sustainable waste management solutions. This research highlights the value of academia–industry collaboration in advancing environmentally responsible practices and reinforces the contribution of RFNS to enhancing local infrastructure and promoting a more sustainable future.