This study investigates the potential of hard resin derived from the Yang tree (HY), a renewable bio-based byproduct, as a performance-enhancing additive in natural rubber-modified asphalt (NRMA). HY-modified binders (HYMA) containing 3%, 7%, and 15% HY by weight were evaluated through a multi-scale experimental program, including physical, rheological, thermal, chemical, and mechanical tests. Standard binder characterizations (penetration, ductility, softening point, viscosity), spectroscopic analyses (FT-IR, NMR), microstructural observations (ESEM, XRD), thermal profiling (DSC), and performance assessments (DSR, Marshall) were conducted. The results demonstrated that HY improved binder properties at optimal concentration by introducing additional hydrocarbon structures without chemical cross-linking. HYMA3 achieved the most favorable balance of stiffness, flexibility, and compaction efficiency, whereas higher HY contents (≥7%) impaired structural integrity and deformation resistance. Microstructural and thermal evidence confirmed surface modifications and altered thermal transitions, which influenced viscoelastic response. These findings provide new insights into bio-resin–asphalt interactions and establish the viability of HY as a sustainable alternative to synthetic polymer modifiers. Beyond performance improvement, HY promotes circular construction by transforming agricultural byproducts into functional pavement materials, supporting the development of climate-adaptive infrastructure.

This study investigates the efficiency of the recently developed Elitist Stepped Distribution Algorithm (ESDA) as a metaheuristic framework for truss sizing optimization. ESDA builds upon the Cross-Entropy Method by introducing an elitist stepped sampling strategy that improves the balance between exploration and exploitation during the search process. To evaluate its effectiveness, ESDA is applied to a comprehensive test suite comprising seven benchmark truss optimization problems that cover a wide range of sizes, design variables, loading conditions, and constraint types. In all cases, the objective is to minimize structural weight while satisfying stress, displacement, and stability requirements. Numerical experiments are conducted with the proposed method, and the results are compared with those algorithms reported in the literature. The findings show that ESDA attains new best or near-best solutions for large-scale problems such as the 117-bar cantilever, 130-bar transmission tower, 354-bar dome, and 942-bar tower trusses, while also producing competitive results for the 25-bar, 72-bar, and 200-bar structures with relatively modest computational effort. The novelty of this work lies in demonstrating the robustness, efficiency, and scalability of ESDA across diverse benchmarks, highlighting its potential for future structural optimization applications.

Disconnecting pile heads from the raft has gained wide application because the gravel and geogrid layers filling the space between them create a more even pressure distribution and reduce differential settlement. However, due to the complexity of modelling the multiple interfaces in the superstructure-foundation-subsoil system, previous findings on load-transfer mechanisms, interaction effects, and group optimization remain incomplete. Moreover, the common analytical approach employed for understanding the load transfer mechanism is the “unit cell’ concept, which cannot fully capture dissimilarity in the group. To address these limitations, this study aims to develop an analytical framework for predicting the load-settlement response of cushioned piled rafts with dissimilar piles. The proposed method simplifies the cushion-pile-soil interaction using a Winkler-type Spring model, while a hyperbolic load-transfer function captures the nonlinear pile-soil behavior. The model was verified against existing experimental and showed close agreement. It successfully captured the load-sharing mechanism, confirming that stiffer, longer, or larger-diameter piles attract a disproportionately higher share of the load. The novelty of this work lies in the establishment of an analytical model based on the principles of dissimilar pile groups but extended to include cushion force transmission, a critical integration that provides a realistic tool for practice.

This article examines the development of a methodology for monitoring geodynamic processes during the construction of the Almaty metro using an integrated approach that incorporates geodetic methods, laser scanning, and aerospace technologies. The study aims to enhance the safety of underground structures in the context of complex engineering-geological conditions and high-density urban environments. Monitoring was conducted at the "Saryarka" and "Bauyrzhan Momyshuly" stations, employing underground polygonometry, aerial surveys with unmanned aerial vehicles (DJI Mavic 3 multispectral), laser scanning (Faro Focus 3D X), and finite element numerical modeling (PHASE 2, AutoCAD Civil 3D). The geodetic work covered a 3201-meter section with the installation of 34 benchmarks, ensuring a relative measurement error of no more than 1:30,000. Laser scanning achieved an average point cloud density of 7 mm, enabling the creation of precise 3D tunnel models, identification of deviations from the design axis, and determination of critical stress zones. The study revealed that at a depth of 32.28 m, the maximum vertical stress reached 11.2 MPa, and horizontal stress was 2.7 MPa. At a depth of 19.58 m, the vertical stress reached 10.5 MPa, while the horizontal stress was 2.47 MPa. The maximum concentration of stresses in critical zones reached 20 MPa. The use of UAVs and aerospace technologies facilitated the creation of a highly accurate digital terrain model and the identification of potential deformation zones. The findings confirm the necessity of regular monitoring in dense urban and seismically active areas and demonstrate the potential of integrating modern technologies to improve the precision and efficiency of geodynamic assessments. The proposed methodology can be applied not only to metro construction but also to other underground structures, including mining industry facilities, both in Kazakhstan and internationally.

Lateritic soils, which are widespread in intertropical regions and traditionally used as pavement sub-base layers in Burkina Faso, often exhibit low geomechanical performance, thereby limiting their long-term durability under increasingly heavy traffic loads. This study investigates a combined stabilization approach consisting of incorporating 20% of 10/20 crushed granite aggregates together with low cement content (0%, 1%, 2%, and 3%). The objective was to improve both the mechanical properties and fracture behavior of these soils, while reducing the environmental footprint associated with cement use. Accordingly, an experimental program was carried out, including geotechnical tests (maximum dry density, optimum moisture content, and CBR at 95% compaction) and mechanical characterizations (unconfined compressive strength, indirect tensile strength, Young’s modulus, and full stress–strain behavior under uniaxial compression). The results revealed substantial improvements when 20% aggregates and 3% cement were added to the raw soil: the maximum dry density increased by approximately 5%, the CBR by 2253%, the compressive strength by 134%, the indirect tensile strength by 85%, and the Young’s modulus by 195%. Regarding fracture behavior, the same mixture showed an enhanced energy absorption capacity, with increases of approximately 40% for fracture energy, 65% for peak energy, 87% for elastic energy, 18% for plastic energy, and 5% for post-peak energy. These findings confirm that the combination of crushed aggregates and low cement content produces a synergistic effect, yielding a material that is stronger, stiffer, more water resistant, and more ductile. Thus, innovative stabilization approach represents a promising alternative for sustainable road construction.

Soft clay subgrade is unsuitable for road pavement because it has low bearing capacity and CBR value. Therefore, the soil needs stabilization, but with a sustainable stabilization method. One of these methods is biogrouting, namely grouting, which uses bacteria. Thus, the main objective of this study was to determine the performance of Bacillus subtilis and Bacillus amyloliquefaciens bacteria in stabilizing the soil. The performance of these bacteria was quantified by the CBR value and soil-bearing capacity experimentally in a laboratory model test with each soil thickness of 0-30 cm. The CBR value of the soil improved by the biogrouting method by about 4 times the CBR value of untreated soil. The increase in bearing capacity was obtained about 4 times for treated soil with Bacillus subtilis and about 5 times for treated soil with Bacillus amyloliquefaciens. The layer thickness significantly improves the performance of the subgrade at a layer thickness of 20 cm. The new result of this study is that both bacteria are native Indonesian bacteria, so they are suitable for use in Indonesia. In addition, Bacillus amyloliquefaciens has never been used in research to increase soil-bearing capacity.

The Life Cycle Assessment (LCA) of asphalt pavements is an essential tool for reducing environmental impacts. The definition of the functional unit (FU) within LCA can significantly influence the results, affecting the assessment of greenhouse gas (GHG) emissions and, consequently, the selection of asphalt mixtures. In this context, this study aims to analyze the impact of different functional units on the selection of asphalt mixtures for road pavements, considering the phases of raw material extraction, material production, mixing, and construction. To this end, the mechanical behavior of two distinct asphalt mixtures was evaluated under two different loading conditions, and their contributions to climate change were assessed using three functional units: t CO₂ eq/km of roadway, kg CO₂ eq/t of HMA, and kg CO₂ eq/m³ of HMA. The results indicated that asphalt mixtures with a higher resilient modulus require thinner pavement layers, leading to lower GHG emissions. However, when asphalt mixtures are analyzed individually and compared, no clear pattern in GHG emissions is observed, reflecting the specific characteristics of each production process. Additionally, it was found that the environmental impact varied according to the adopted functional unit, demonstrating that this choice can significantly influence decision-making regarding the selection of asphalt mixtures in terms of their contributions to climate change. It was concluded that the selection of the FU in pavement LCA should be aligned with the study's objective and the context of the analysis, as an inadequate choice may compromise the selection of asphalt mixtures.

This study investigated the behavior of masonry-infilled walls (MIWs) within reinforced concrete (RC) frames when exposed to hydrodynamic forces from tsunamis by employing a multi-spring modeling approach across different inundation levels. The proposed analytical model divided the MIW into 1 to 5 horizontal nonlinear spring elements that were allocated along the wall's height. Each spring represented a segment of MIW and was defined by a tri-linear force–displacement relationship. The model was calibrated with the experimental data from previous studies and was analyzed using pushover assessment under uniformly distributed hydrodynamic forces corresponding to four tsunami inundation levels (0.25H, 0.50H, 0.75H, and 1.00H). The models, which had employed four or five horizontal springs, had most effectively replicated MIW behavior under tsunami loading at all inundation depths. Conversely, single-spring models tend to overestimate lateral resistance by up to 50%, particularly when the frame is only partially submerged. This discrepancy arises because less force is transmitted through the MIW, with a greater amount of it being transferred directly to the foundation. The utilization of several spring elements provided a realistic load path, improved the interaction between the frame and MIW characterization, and optimized the precision in simulating lateral resistance and post-peak behavior.

This study investigates the structural performance of semi-precast concrete slabs (SPCSs), an innovative hybrid construction system that integrates factory-produced precast concrete units with a cast-in-place (CIP) concrete topping to create a composite structural element. This system offers notable advantages in terms of construction acceleration, improved quality control, and reduced labor requirements, as the precast unit serves as both a load-bearing component and a permanent formwork. To evaluate the structural behavior of the SPCSs, an experimental program was conducted on seven full-scale, one-way slab specimens with varying span lengths (4.75 m and 6.0 m), precast unit thicknesses (80 mm and 100 mm), and shear connector geometries (rectangular and triangular). A control slab without shear connectors was also tested to establish a baseline for comparison. The results demonstrated that the inclusion of shear connectors significantly enhanced structural performance. Specifically, the ultimate load capacity increased by 186.4%, and the cracking load increased by 220% compared to the control specimen. Rectangular connectors proved more effective than triangular ones in minimizing interface slip and enhancing ductility. The initial stiffness increased by 163.95%, while the energy dissipation capacity improved by 411.35%. Although variations in span length and topping thickness had relatively minor effects, the presence and geometry of shear connectors played a decisive role in ensuring effective composite action. All reinforced slabs exhibited flexural failure modes, indicating strong bonding and interaction between the precast and cast-in-place (CIP) concrete layers, whereas the control slab experienced premature failure due to interlayer debonding. Theoretical equations based on ACI 318-19 were used to estimate the nominal flexural capacities of the hybrid SPCS slabs, showing reliable agreement with the experimental results. These findings demonstrated the importance of shear connector design in maximizing the load-bearing capacity, ductility, and structural stiffness of SPCS systems under both service and extreme loading conditions.

The soil erosion risk on the slopes in Luong Son District, Hoa Binh Province, Vietnam, was determined to inform sustainable land management and conservation planning. Remote sensing and geographic information system (GIS) technologies were integrated with the universal soil loss equation (USLE) model to generate thematic maps of rainfall erosivity (R), soil erodibility (K), topographic factors (LS), and vegetation cover. These maps were combined to produce a comprehensive soil erosion risk map. The results showed that 65.09% of the district (23,747.61 hectares), mainly flat and midland areas, had no erosion risk. Light, moderate, and severe erosion affected 19.95%, 7.61%, and 7.35% of the region, respectively. Higher erosion risk is concentrated in mid-level mountainous and limestone regions, characterized by steep slopes and sparse vegetation. These findings highlight the influence of slope gradient and length on erosion severity and spatial patterns. Remote sensing, GIS, and USLE were integrated to spatially assess soil erosion, providing a scientific basis for targeted interventions, such as reforestation and terrace farming. This study contributes to gaps in the literature by comprehensively analyzing spatial soil erosion risk and providing practical recommendations for mitigating soil erosion in vulnerable landscapes and supporting sustainable land use planning under climate change pressures.