Search Results (501)

In response to the escalating climate crisis, reducing greenhouse gas emissions (GHG) has become a top priority for both the public and private sectors. The pavement industry plays a key role in this transition, offering innovative technologies that minimize environmental impacts without compromising performance. Among these, the incorporation of recycled tire rubber and warm-mix asphalt (WMA) additives represents a promising strategy to reduce energy consumption and resource depletion in road construction. This study conducts a comparative life cycle assessment (LCA) to evaluate the environmental performance of an asphalt pavement incorporating recycled rubber and a WMA additive—referred to as R-W asphalt—against a conventional hot-mix asphalt (HMA) pavement. The analysis follows the ISO 14040/44 standards, covering material production, transport, construction, and maintenance. Two service-life scenarios are considered: one assuming equivalent durability and another with a five-year extension for the R-W pavement. The results demonstrate environmental impact reductions of up to 57%, with average savings ranging from 32% to 52% across key impact categories such as climate change, land use, and resource use. These benefits are primarily attributed to lower production temperatures and extended maintenance intervals. The findings underscore the potential of R-W asphalt as a cleaner engineering solution aligned with circular economy principles and climate mitigation goals. Full article

Optimisation of the anti-skid properties of tyres is a significant area of composite applications. For investigating the wet slip friction characteristics, the wet slip friction test of tread rubber and road surface was carried out using the comprehensive tire friction testing machine. The wet slip properties of different formulated rubbers under various working conditions such as different slip speeds, water film thicknesses and vertical loads were compared through the test. Subsequently, an orthogonal test programme was designed to investigate the degree of significant influence of each factor on the wet slip performance. A three-dimensional finite element model of tread rubber and road surface with water film was established in order to facilitate analysis of the wet slip properties. The simulation results were utilised to elucidate the pattern of the effects of different loads on the wet slip friction characteristics. Results indicate that the wet slip friction coefficient is subject to decrease in proportion to the magnitude of the vertical load; the friction coefficient of rubber block in wet slip condition exhibits a decline of approximately 26% in comparison with that of dry condition; the factor that exerts the most significant influence on the coefficient of friction is the vertical load, while the water film thickness exerts the least influence. The results obtained can serve as a reference source for the design of tire anti-skid performance enhancement. Full article

This study investigates the development of a tire wear model using finite element techniques. Experimental testing was conducted using the Hoosier R25B slick tire mounted onto a Mustang Dynamometer (MD-AWD-500) in the Automotive Center of Excellence, Oshawa, Ontario, Canada. A general acceleration/deceleration procedure was performed until the battery was completely exhausted. A high-fidelity finite element tire model using Virtual Performance Solution by ESI Group, a part of Keysight Technologies, was developed, incorporating highly detailed material testing and constitutive modeling to simulate the tire’s complex mechanical behavior. In conjunction with a finite element model, Archard’s wear theory is implemented algorithmically to determine the wear and volume loss rate of the tire during its acceleration and deceleration procedures. A novel application using a modified wear theory incorporates the temperature dependence of tread hardness to measure tire wear. Experimental tests show that the tire loses 3.10 g of mass within 45 min of testing. The results from the developed finite element model for tire wear suggest a high correlation to experimental values. This study demonstrates the simulated model’s capability to predict wear patterns, ability to quantify tire degradation under dynamic loading conditions and provides valuable insights for optimizing performance and wear estimation. Full article

This study investigates measurement methods for and the distribution characteristics of normal stress within tire–road contact areas. A novel measurement method, integrating 3D scanning technology with bearing area curve (BAC) analysis, is proposed. This method quantifies the rubber penetration depth and calculates contact stress based on rubber deformation. The key innovation of this method lies in this integrated methodology for high-precision stress mapping. In the spatial domain, stress distribution is characterized by the percentage of area occupied by different stress intervals, while in the frequency domain, stress levels are analyzed at various frequencies. The results demonstrate that as the Mean Profile Depth (MPD) of the road texture increases, the areas under stress greater than 1.0 MPa increase, while the areas under stress less than 0.8 MPa decrease. However, when the MPD exceeds 0.7 mm, this effect becomes less pronounced. Higher loads and harder rubber reduce the proportion of areas under lower stress and increase the proportion under higher stress. Low-frequency (<800 1/m) stress components increase with an MPD up to 0.7 mm, beyond which they exhibit diminished sensitivity. Stress at the same frequency is not significantly affected by load variation but increases markedly with increasing rubber hardness. This research provides crucial insights into contact stress distribution, establishing a foundation for analyzing road friction and optimizing surface texture design oriented towards high-friction pavements. Full article

Traditional ultra-thin asphalt wearing course designs often oversimplify wheel loads as uniform pressures, neglecting critical non-uniform effects. This study establishes a 3D finite element model incorporating realistic non-uniform tire loading to reveal its mechanistic influence on pavement responses. Results demonstrate that non-uniform loading significantly alters stress states in ultra-thin layers, substantially elevating critical stresses compared to uniform assumptions. A novel Non-uniform Load Influence Factor (NLIF) accounting for thickness effects is developed to quantify these deviations. The analysis provides a foundation for revising material strength specifications and fatigue design criteria, contributing to improved performance and durability of ultra-thin pavement systems. Full article

In China, the recycling system for waste tires is characterized by high output but low standardized recovery rates. This study examines the environmental and health risks caused by non-compliant treatment by individual recyclers and explores the barriers to the large-scale adoption of Pyrolysis Technology. A Tripartite Evolutionary Game Model involving pyrolysis plants, waste tire recyclers, and government regulators is developed. The model incorporates pollutants from pretreatment and pyrolysis processes into a unified metric—Carbon Dioxide Equivalent (CO₂-eq)—based on Global Warming Potential (GWP), and designs a Differential Carbon Taxation mechanism accordingly. The strategy dynamics and stability conditions for Evolutionary Stable Strategies (ESS) are analyzed. Multi-scenario numerical simulations explore how key parameter changes influence evolutionary trajectories and equilibrium outcomes. Six typical equilibrium states are identified, along with the critical conditions for achieving environmentally friendly results. Based on theoretical analysis and simulation results, targeted policy recommendations are proposed to promote standardized waste tire pyrolysis: (1) Establish a phased dynamic carbon tax with supporting subsidies; (2) Build a green market cultivation and price stabilization system; (3) Implement performance-based differential incentives; (4) Strengthen coordination between central environmental inspections and local carbon tax enforcement. Full article

Ultra-high-performance concrete (UHPC) reinforced with recycled tire steel fibers (RTSFs) was studied to evaluate its mechanical properties and cracking behavior. Using acoustic emission (AE) monitoring, researchers tested various RTSF replacement rates in compression and flexural tests. Results revealed a clear trend: mechanical properties initially improved then declined with increasing RTSF content, peaking at 25% replacement. AE analysis showed distinct patterns in energy release and crack propagation. Signal timing for energy and ringing count followed a delayed-to-advanced sequence, while b-value and information entropy changes indicated optimal flexural performance at specific replacement rates. RA-AF classification demonstrated that shear failure reached its minimum (25% replacement), with shear cracks increasing at higher ratios. These findings demonstrate RTSFs’ dual benefits: enhancing UHPC performance while promoting sustainability. The 25% replacement ratio emerged as the optimal balance, improving strength while delaying crack formation. This study provides insights into the mechanism by which waste tire steel fibers enhance the performance of UHPC. This research provides valuable insights for developing eco-friendly UHPC formulations using recycled materials, offering both environmental and economic advantages for construction applications. Full article

The inclusion of adsorption thermodynamic analysis and performance benchmarking with existing adsorbents reinforces both the theoretical significance and practical applicability of this study. The modified rubber-derived carbon demonstrated a remarkably high DBT adsorption capacity of 254.45 mg/g. These results establish it as a promising alternative to conventional materials such as commercial activated carbon, zeolites, and even metal–organic framework materials. In addition to confirming the superior performance of the adsorbent, the findings provide a deeper understanding of the DBT adsorption mechanism and offer a solid scientific basis for large-scale fuel desulfurization applications. This research highlights the potential of transforming end-of-life tire waste into value-added functional materials and contributes to the advancement of sustainable and efficient desulfurization technologies. Future work should focus on optimizing surface functionalization and regeneration strategies to further improve long-term adsorption stability and practical deployment. Full article

Wheel-legged robots combine the advantages of both wheeled robots and traditional quadruped robots, enhancing terrain adaptability but posing higher demands on the perception of foot–ground contact forces. However, existing approaches still suffer from limited accuracy in estimating contact positions and three-dimensional contact forces when dealing with flexible tire–ground interactions. To address this challenge, this study proposes a foot–ground contact state detection technique and optimization method based on multi-sensor fusion and intelligent modeling for wheel-legged robots. First, finite element analysis (FEA) is used to simulate strain distribution under various contact conditions. Combined with global sensitivity analysis (GSA), the optimal placement of PVDF sensors is determined and experimentally validated. Subsequently, under dynamic gait conditions, data collected from the PVDF sensor array are used to predict three-dimensional contact forces through Gaussian process regression (GPR) and artificial neural network (ANN) models. A custom experimental platform is developed to replicate variable gait frequencies and collect dynamic contact data for validation. The results demonstrate that both GPR and ANN models achieve high accuracy in predicting dynamic 3D contact forces, with normalized root mean square error (NRMSE) as low as 8.04%. The models exhibit reliable repeatability and generalization to novel inputs, providing robust technical support for stable contact perception and motion decision-making in complex environments. Full article

To address the issues of high carbon emissions from concrete and high energy consumption in the manufacturing of traditional steel fibers, this study investigates the feasibility of replacing industrial steel fibers (ISF) with recycled tire steel fibers (RSF) in high-performance cement-based materials. The study examines the effects of fiber type and dosage on the mechanical properties within the systems of ultra-high-performance concrete (UHPC) and slurry-infiltrated fiber concrete (SIFCON) and analyzes the carbon emission levels using the Life Cycle Assessment (LCA) method. Research results indicate that the compressive and tensile strengths of SIFCON are significantly higher than those of UHPC. Under the same conditions, RSF has little difference in tensile performance when compared with ISF, suggesting a great substitution potential. Carbon emission analysis shows that although the total carbon emissions of the SIFCON system are relatively high, its performance improvement is remarkable. Both the carbon emission per tensile strength and carbon emission per compressive strength are lower than those of UHPC, demonstrating a high degree of environmental friendliness. Overall, this study shows that RSF can not only effectively enhance the performance of high-performance cement-based materials but also reduce carbon emissions, making it a reinforcing material with both excellent performance and sustainability. Full article

With the advancement of logistics technology, Automated Guided Vehicles (AGVs) have been widely adopted in manufacturing enterprises due to their high flexibility and stability, particularly in flexible and discrete manufacturing domains such as tire production and electronic assembly. However, existing studies seldom systematically consider practical constraints such as limited AGV transport resources, AGV charging requirements, and charging station capacity limitations. To address this gap, this paper proposes a flexible job shop production-logistics collaborative scheduling model that incorporates transport and charging constraints, aiming to minimize the maximum makespan. To solve this problem, an improved PPO algorithm—CRGPPO-TKL—has been developed, which integrates candidate probability ratio calculations and a dynamic clipping mechanism based on target KL divergence to enhance the exploration capability and stability during policy updates. Experimental results demonstrate that the proposed method outperforms composite dispatching rules and mainstream DRL methods across multiple scheduling scenarios, achieving an average improvement of 8.2% and 10.5% in makespan, respectively. Finally, sensitivity analysis verifies the robustness of the proposed method with respect to parameter combinations. Full article

This study aims to investigate the application of nuclear magnetic resonance (NMR) to characterize mortars containing recycled rubber waste as an eco-innovative material for sustainable construction. The primary objective was to analyze the way rubber granules influence hydration kinetics, microstructural development and pore structure. The innovative mortar formulations incorporated rubber granules, casein, natural hydraulic lime (NHL), and latex. NMR analysis revealed distinct T₂ relaxation time distributions correlated with different pore sizes and water states: shorter T₂ values demonstrate strongly bound water in small pores, while longer T₂ values are associated with loosely bound or free water in larger pores. The formulation with 3.5% NHL and 5% rubber granules exhibited optimal microstructural characteristics. These results reveal that NMR is a valuable, non-destructive tool for monitoring cementitious material evolution and supporting the use of tire-derived waste in eco-innovative mortar designs. Full article

Crosslinked phenolic resin was prepared using hexamethylenetetramine (HMTA) as a crosslinking agent in hydrochloric acid solution. The ablation-heat-resistant material was prepared by a pressure-assisted RTM (resin transfer molding) process with reinforcing material (quartz fibre 2.5D needle-punched fabric/satin fibre cloth/fibre mesh tire) and matrix (crosslinked phenolic resin). The thermal stability of the cured product was studied by a thermogravimetric analyser (TG and DTG). The mechanical properties, heat resistance, and ablation properties of the composites were tested. The ablation morphology, element analysis, and phase structure of the composites were analysed by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and X-ray diffraction (XRD), respectively. The results show that the phenolic resin has a lower initial viscosity and a longer pot life at 80 °C, and a higher carbon residue rate (70.18%). The tensile strength of the composites is close to 40 MPa, the tensile modulus is higher than 1.35 GPa, the compression modulus is higher than 10 MPa, and the elongation at break is higher than 1.55%. SiO₂, SiC, and ZrO₂ ceramic phases were formed after ablation, which effectively improved the ablation performance of the composites. Full article

The contact characteristics of radial tires are crucial for optimizing stress distribution, deformation, and wear. The non-uniform contact stress behavior induced by complex tread patterns remains under-explored in existing tire mechanics research. Taking the 205/50R17 radial tire as a representative case, a reverse modeling approach was employed to develop an accurate finite element model for tires incorporating intricate tread pattern features. The fidelity of the proposed tire simulation model was confirmed utilizing high-precision contour profiling techniques. The impact of diverse usage conditions and design parameters on the tire outer profile and ground contact characteristics under static and free-rolling states was analyzed. Experimental observations demonstrate that the increased inflation pressure leads to a proportional decrease in contact area. Under incremental vertical loading, the contact patch develops progressively into a saddle-shaped geometry featuring elevated shoulder regions and a recessed central zone. Increasing the belt angle compromises its hoop-stiffening function, thereby inducing elliptical contact patch geometry. Larger design diameters compromise contact length symmetry in shoulder regions. Variation in shoulder thickness at 85% of the tread width results in a significant difference in contact length between the left and right tread blocks in the rolling state. This work enables refinement strategies for both tread configurations and tire dimensional designs in industrial applications. Full article

Rubber is widely used in daily lives, such as in automobile tires, conveyor belts, sealing rings, and gaskets. The performance of rubber determines its service life. Therefore, it is of crucial importance to improve the performance of rubber. Theoretical studies have found that the inherent properties of nanofillers themselves, the interfacial bonding force between fillers and the matrix, and the uniform dispersibility of nanofillers in the polymer matrix are the most significant factors for enhancing the performance of rubber nanocomposites. This study systematically investigated the synergistic enhancement effect of silicon carbide (SiC) and multi-walled carbon nanotubes (MWCNTs) on the mechanical and thermal properties of ethylene–butene–terpolymer (EBT) composites. By optimizing the addition amount of fillers and improving the interfacial bonding between fillers and the matrix, the influence of filler content on the properties of composites was studied. The results demonstrate that the addition of SiC and MWCNTs significantly improved the storage modulus, tensile strength, hardness, and thermal stability of the composites. In terms of mechanical properties, the tensile strength of the composites increased from 6.68 MPa of pure EBT to 8.46 MPa, and the 100% modulus increased from 2.14 MPa to 3.81 MPa. Moreover, hardness was significantly enhanced under the reinforcement of SiC/CNT fillers. In terms of thermal stability, the composites exhibited excellent resistance to deformation at high temperatures. Through the analysis of the mechanical and thermal properties of the composites, the synergistic enhancement mechanism between SiC and MWCNTs was revealed. The research results provide a theoretical basis for the design and engineering applications of high-performance ethylene–butylene rubber composites. Full article