Structural Analysis of Flexible Pavements with HMA Exposed to Short-Term Aging Taciano Oliveira da Silva, Klaus Henrique de Paula Rodrigues, Heraldo Nunes Pitanga, Francisco Aureliano Rocha de Vasconcelos Teixeira, Kelbia da Silva Santos, et al. Infrastructures, 2026 This study presents a comparative evaluation of the structural performance of flexible pavements made from different hot mix asphalt (HMA). HMAs were proportioned using the conventional Marshall method and HMAs subjected to short-term aging were analyzed. Grades B (binder course) and C (surface course), according to DNIT specifications, were used. After determining the aggregate gradation and asphalt content using the Marshall method, test specimens were produced and tested in the laboratory to determine the mechanical parameters characteristic of each HMA (stability, tensile strength by diametral compression, resilient modulus, fatigue behavior, and permanent strain). The Elsym5 software was used to carry out a structural analysis of an assumed pavement, whereby only the mechanical properties of the surface course and the binder course were varied. The results showed that short-term aging significantly affected the mechanical behavior of HMA and the structural response of flexible pavements. Better structural performance was observed in HMAs subjected to short-term aging. The aged specimens showed an improvement in mechanical properties compared to specimens produced by the conventional method, indicating a promising approach for optimizing pavement performance. These results provided new parameters for investigation and development in the field of road engineering.
Mechanical and Microstructural Evaluation of Compacted Mixtures of Tropical Soils with Expanded Polystyrene (EPS) Waste for Sustainable Construction Applications Gian Fonseca dos Santos, Heraldo Nunes Pitanga, Klaus Henrique de Paula Rodrigues, Gustavo Henrique Nalon, Taciano Oliveira da Silva Buildings, 2025 Expanded polystyrene (EPS), a lightweight thermoplastic polymer widely used in packaging and insulation, has become a growing environmental concern due to its non-biodegradable nature and escalating global consumption. Although EPS waste shows potential in construction applications, previous studies have primarily incorporated it into mortars, concrete, or soil–cement mixtures, often relying on the addition of cement to improve its mechanical performance. This approach compromises sustainability and has generally overlooked the role of microstructural interactions in the behavior of soil–EPS waste mixes without cement. This study differs from prior works by exploring the mechanical and microstructural properties of soil–EPS waste mixtures without cementitious binders under different compaction energies. Experimental tests were carried out for the technical characterization of soils, ground EPS waste, and mixtures of soil and different contents of EPS waste (0%, 20%, 30%, and 40% of the total apparent volume of the composite), using different compaction energies (Intermediate and Modified Proctor). The mixtures were subjected to Unconfined Compressive Strength (UCS), California Bearing Ratio (CBR), and direct shear strength tests, in addition to physical and microstructural characterization. The results indicated that both soil type and compaction energy influenced the engineering behavior of the mixtures. The clayey soil exhibited superior mechanical performance, while the sandy soil showed reductions in all mechanical properties. The UCS values of the clayey soil with the addition of EPS did not change significantly (297 kPa to 286 kPa at intermediate energy and 514 kPa to 505 kPa at modified energy), while for the sandy soil, there was a decrease in values (from 167 kPa to 46 kPa at intermediate energy and from 291 kPa to 104 kPa at modified energy). In the CBR tests, only the 20% and 30% addition of EPS to the clayey soil, using the Modified Proctor energy, showed an increase (from 18% to 20% for both percentages). This behavior was primarily attributed to adhesion mechanisms at the soil–EPS waste interface, with friction playing a secondary role, thereby suggesting that clayey soils may offer better mechanical response. The lower dry density of these mixtures compared to compacted natural soils presents a technical benefit for use as backfill in areas with low bearing capacity, where minimizing the load from the fill material is critical.
Mechanical Behavior of Geopolymers Containing Soil and Red Mud Stabilized by Alkali Activation Ana Carolina Pereira da Silva, Klaus Henrique de Paula Rodrigues, Gustavo Henrique Nalon, Heraldo Nunes Pitanga, Natália Assunção Brasil Silva, et al. Buildings, 2025 The urgent demand for environmentally responsible construction practices has intensified interest in geopolymer concrete mixtures, which offer low-carbon alternatives to conventional Portland cement by enabling the valorization of industrial by-products. Since the large volume of waste generated by mining activities represents a significant environmental liability, this research aimed to utilize the alkali activation technique in mixtures of soil and bauxite residue, commonly known as red mud (RM), for application in green construction. All raw materials were characterized based on their physical and chemical properties. To evaluate the influence of waste content on the mechanical behavior of the geopolymers, specimens were prepared with soil contents ranging from 70% to 100% and RM dosages ranging from 0% to 30%. These mixtures underwent compaction tests using the standard Proctor energy method to determine maximum dry density and optimum moisture content. Using the optimal mixture compositions, specimens were prepared for unconfined compressive strength (UCS) tests, with NaOH at a concentration of 6 mol/L added as an activator. The experimental tests provided UCS results ranging from 2.23 MPa to 3.05 MPa. X-ray diffraction (XRD) analyses were performed on raw materials and mixtures containing 70% soil and 30% waste to assess changes in mineralogical compositions due to waste incorporation. The results confirmed the potential of alkali activation for stabilizing mixtures of soil and RM for sustainable construction.
Efficacy of the Simplex-Centroid Method for Optimization of Mixtures of Soil, Ladle Furnace Slag and Fly Ash Applied in Pavement Construction Mateus Henrique Ribeiro Rodrigues, Taciano Oliveira da Silva, Heraldo Nunes Pitanga, Leonardo Gonçalves Pedroti, Klaus Henrique de Paula Rodrigues, et al. Sustainability Switzerland, 2024 Integrating industrial wastes into soils to enhance their properties is a potential solution to current waste management challenges. Since the current literature lacks systematic studies on the mechanical performance of mixtures of soil, ladle furnace slag (LFS) and fly ash (FA), this research investigated the chemical stabilization of two different soils (clayey or sandy soil) using a concomitant mix of distinct types of industrial wastes: LFS and FA. A design of experiments (DoE) methodology was employed to systematically generate distinct mixtures for each soil sample, utilizing a simplex-centroid design. The mixtures were subjected to unconfined compressive strength (UCS), California Bearing Ratio (CBR) and resilient modulus (RM) tests. The industrial by-products improved the mechanical properties of the soils, providing UCS, CBR index and RM increases up to 130.5%, 324.4% and 132.6%, respectively. Synergistic and antagonistic effects related to the combination of different wastes were discussed, based on mathematical models with coefficients of determination ranging from 0.760 to 0.998, in addition to response surfaces generated for each response variable. The desirability function was applied to identify the optimal component proportions. The best mixture proportion was 80% soil, 20% LFS and 0% FA, which improved the formation of cemented compounds that contributed to the enhanced mechanical strength. The use of industrial waste for soil stabilization has therefore proven to be technically feasible and environmentally friendly.
Optimization Models for the Maintenance Management of Tropical Paved and Unpaved Roads Taciano Oliveira da Silva, Heraldo Nunes Pitanga, Emerson Cordeiro Lopes, Laura Carine Pereira Ribeiro, Gustavo Henrique Nalon, et al. Infrastructures, 2024 The degradation of paved and unpaved roads stands as a critical concern in contemporary infrastructure management. When faced with limited budgets, it is important to identify the optimal combination of road preservation strategies to minimize the lifecycle cost of the road network. Specific studies are necessary to improve the maintenance management systems and analyze the behavior of road surface deformation. To narrow these knowledge gaps, this study investigates a management system that focuses on the application of optimization techniques for managing both paved and unpaved tropical roads. Probabilistic deterioration models were constructed using the Markovian process, resulting in precise degradation curves in the context of 18 unpaved road segments in the Zona da Mata County of Minas Gerais (Brazil), along with 88 paved roads located in Minas Gerais. An optimization algorithm was proposed for the prediction of maintenance resources for unpaved and paved roads, emphasizing the cost-effectiveness of preventive and minor rehabilitation treatments over reconstruction. Comparisons between the maintenance costs of unpaved and paved roads indicated that the full rehabilitation costs of paved roads were approximately 10 times higher per kilometer compared to those of unpaved roads. The models effectively captured the trend wherein a major treatment leads to minor additional treatments being necessary for the subsequent several years in both scenarios. The findings of this study provide future directions for the optimized allocation of resources in the management of transportation infrastructures.
