Search Results (603)

Steel bridge deck pavements (SBDPs) are susceptible to complex mechanical and service environmental conditions, yet current design methods often struggle to simultaneously capture global bridge system behavior and local pavement responses. To address this issue, this study develops a multi-scale finite element modeling framework that integrates a full-bridge model, a refined girder-segment model, and a detailed pavement submodel. The framework is applied to an extra-long suspension bridge to evaluate the mechanical responses of five typical pavement structural configurations—including double-layer SMA, double-layer Epoxy Asphalt (EA), EA-SMA combinations, and a composite scheme with a thin epoxy resin aggregate overlay. By coupling global deformations from a full-bridge model to the local pavement submodel, the proposed method enables a consistent assessment of both bridge-level effects and pavement-level stress concentrations. The analysis reveals that pavement structures significantly alter the stress and strain distributions within the deck system. The results indicate that while the composite configuration with a thin overlay effectively reduces shear stress at the pavement–deck interface, it results in excessive tensile strain, posing a high risk of fatigue cracking. Conversely, the double-layer EA configuration exhibits the lowest fatigue-related strain, demonstrating superior deformation coordination, while the optimized EA-SMA combination offers a robust balance between fatigue control and interfacial stress distribution. These findings validate the effectiveness of the multi-scale approach for SBDP analysis and highlight that rational structural configuration selection—specifically balancing layer stiffness and thickness—is critical for enhancing the durability and long-term performance of steel bridge deck pavements. Full article

This study investigated the noise reduction performance of porous asphalt concrete (PAC) pavement under tire–pavement coupling conditions, addressing the limitations of field measurements and laboratory testing. First, tire excitation amplitude parameters were determined based on vibrational contact operational scenarios. Then, finite element simulations were conducted to systematically analyzing the tire–pavement coupling noise characteristics of PAC pavement. The results indicate that PAC pavement effectively reduces the air pumping noise due to its highly porous internal structure, leading to significant noise attenuation. Furthermore, the study examined the key factors influencing the tire–pavement coupling noise in PAC pavement. When maintaining constant vehicle parameters (300 kg load, 60 km/h speed), pavement thickness became the critical noise-control variable, achieving minimum vibration at 6 cm surface layer thickness. Additionally, tire tread depth (5–17 mm) and mold release angle (0–30°) had a more pronounced impact on the air pumping noise compared to groove width (20–60 mm). Increasing the mold release angle and reducing tread depth effectively mitigated the air pumping noise. However, the tire–pavement coupling noise in PAC pavement increased considerably with increasing vehicle speed and load. Particularly, as the speed increased from 30 km/h to 60 km/h, the growth of the air pumping noise was most pronounced, revealing an acoustic transition of tire–pavement coupling noise from vibration-dominated to air-pumping-dominated mechanisms. Full article

Urban expressways increasingly struggle with declining skid resistance and rising tire–pavement noise as asphalt surfaces age, yet few studies integrate friction, acoustic behavior, and permeability over multiple pavement types and service years. This research provides the first multi-year, multi-indicator field evaluation of four widely used surface systems in Korea (double-layer drainage asphalt, thin-layer low-noise overlays, SMA, and WC-6) linking wet-skid resistance (BPN), rolling friction (GN), acoustic metrics (LAeq, LAFmax), density evolution, and field permeability (Q) into a single performance framework. A three-year dataset from 2021–2024 (n = 20 sites) revealed that wheelpath friction deteriorated steadily at −1.77 BPN/year, with WC-6 exhibiting the fastest decline (≈−5.5 BPN/year) and drainage asphalt the slowest (≈–2.5 BPN/year). Predicted wheelpath service lives spanned 3.8–5.7 years across pavement types. Acoustic monitoring showed a consistent hierarchy (Drainage < Thin-Layer < SMA < WC-6), with WC-6 producing up to 20 dB higher LAFmax due to strong air-pumping effects. Permeability trends mirrored acoustic behavior, with Q decreasing 9–18% over 3 years but maintaining clear ranking: Drainage > Thin-Layer > SMA > WC-6. SMA NMAS analysis further showed that SMA-10 mm delivers higher initial friction but deteriorates faster than SMA-8 mm. Correlation analysis demonstrated that permeability governs both friction and noise (Q vs. LAeq: r = −0.84; Q vs. GN: r = +0.81), confirming the dominant mechanistic role of void connectivity. Collectively, the findings provide quantitative evidence that drainage and thin-layer systems deliver the most balanced long-term performance across safety, noise, and hydraulic functionality, offering practical guidance for pavement selection on noise-sensitive expressways. Full article

Modernizing municipal roads requires rehabilitation strategies that ensure adequate structural performance while reducing environmental and economic burdens. Although cold in-place recycling with foamed bitumen (CIR-FB) has been widely investigated, integrated assessments combining mechanistic–empirical modeling with LCA and LCCA remain limited—particularly for municipal roads in Central and Eastern Europe, where reclaimed asphalt pavement (RAP) quality, climatic conditions and budget constraints differ from commonly studied regions. This study compares two reconstruction variants for a 1 km road section: a conventional design using virgin materials (V₁-N) and a recycling-based alternative (V2-Rc) incorporating RAP from the existing wearing and binder layers and reclaimed aggregate (RA) from the existing base. CIR-FB mixture testing (stiffness ≈ 5.25 GPa; foamed bitumen = 2.5%, cement = 2.0%) was integrated into mechanistic–empirical fatigue analysis, material-flow quantification, LCA and LCCA. The V₂-Rc variant achieved a 3–21-fold increase in fatigue life compared to V₁-N at equal thickness. Material demand decreased by approximately 27%, demolition waste by approximately 39%, and approximately 92% of the existing pavement was reused in situ. Transport work was reduced five-fold (veh-km) and more than six-fold (t-km). LCA showed a 15.9% reduction in CO₂-eq emissions, while LCCA indicated approximately 19% lower construction cost, with advantages remaining robust under ±20% sensitivity. The results demonstrate that CIR-FB, when supported by proper RAP/RA characterization, can substantially improve structural, environmental and economic performance in municipal road rehabilitation. Full article

Traffic Speed Deflectometer (TSD) measures deflection velocities, normalised by travel speed to obtain deflection slopes. Pavement temperature and travel speed can significantly affect deflection slopes. Therefore, correcting deflection slopes for temperature and speed effects is essential. This study employs three-dimensional (3D) finite element simulations of a three-layer flexible pavement system subjected to moving load at travel speeds from 40 km/h to 80 km/h, while varying the Asphalt Concrete (AC) layers’ thickness from 100 mm to 300 mm and the temperature from 5 °C to 45 °C. The results showed that deflection slopes at 100 mm offset distance could be corrected for the effects of temperature and speed using a correction factor comprising the sum of a parabolic function of temperature and a linear function of speed. At 600 mm and 1500 mm offset distances, simpler correction factors could be established using the sum of linear functions of temperature and speed. The Mean Absolute Percentage Error (MAPE) for all predictions was below 3%, indicating high accuracy. Accurate regression-based equations were also proposed to incorporate AC thickness in predicting the correction factors. The results highlight the potential to correct deflection slopes to a reference temperature and speed by evaluating a range of pavement systems. Full article

Urban heat islands intensify heat stress and degrade air quality in densely built areas, yet the physical processes governing near-surface thermal variability remain poorly quantified. This study applies the coupled MOLOCH and PALM model system 6.0 (PALM-4U) over Bologna (Italy) during a summer 2023 heatwave to resolve meter-scale atmospheric dynamics within the Urban Canopy Layer and Roughness Sublayer at 2 m horizontal resolution. The coupled configuration was validated against in situ meteorological observations and Landsat-8 LST data, showing improved agreement in air temperature and wind speed compared to standalone mesoscale simulations. Results reveal pronounced diurnal and vertical variability of wind speed, turbulent kinetic energy, and friction velocity, with maxima between two/three times the median building height (h_c). Distinct surface-dependent contrasts emerge: asphalt and roofs act as strong daytime heat sources (Bowen ratio β_asphalt ≈ 4.8) and nocturnal heat reservoirs at pedestrian level (z ≈ 0.07 h_c), while vegetation sustains daytime latent heat fluxes (β_vegetation ≈ 0.6÷0.8) and cooler surface and near-surface air (Temperature anomaly of surface ΔT_s ≈ −9 °C and air ΔT_air ≈ −0.3 °C). Thermal anomalies decay with height, vanishing above z ≈ 2.5 h_c due to turbulent mixing. These findings provide insight into fine-scale energy exchanges driving intra-urban thermal heterogeneity and support climate-resilient urban design. Full article

Ground-penetrating radar (GPR) is widely used for thickness or compaction degree detection of asphalt pavement layers, where the dielectric properties of asphalt mixtures serve as a key parameter influencing detection accuracy. These properties are closely related to the composition of the mixture and are susceptible to environmental factors such as water or ice. To clarify the influence of various factors on the dielectric behavior of asphalt mixtures, an experimental study was conducted under controlled environmental conditions. Asphalt mixture specimens with different air void contents (5.49~10.29%) were prepared, and variables such as void fraction, moisture, and ice presence were systematically controlled. Air-coupled GPR was employed to measure the specimens, and the relative permittivity was calculated using both the reflection coefficient method (RCM) and the thickness inversion algorithm (TIA). Discrepancies between the two methods were compared and analyzed. Results indicate that the RCM is significantly influenced by surface water or ice and is only suitable for dielectric characterization under dry pavement conditions. In contrast, the TIA yields more reliable results across varying surface environments. A unified model (the optimized shape factor u = −4.5 and interaction coefficient v = 5.1) was established to describe the relationship between the dielectric properties of asphalt mixtures and their volumetric parameters (bulk specific density, air void content, voids in mineral aggregate, and voids filled with asphalt). This study enables quantitative analysis of the effects of water, ice, and mixture composition on the dielectric properties of asphalt mixtures, providing a scientific basis for non-destructive and accurate GPR-based evaluation of asphalt pavements. Full article

To study the mechanical response of the joint under the lateral synergistic action of articulated assembled subgrade, and to screen out the joint materials with the best suitability, this paper establishes a finite element model of an articulated, assembled base-layer asphalt pavement using ABAQUS. It analyses the influence of articulated reinforcement, structural layer, and material parameters on the mechanical response of the joint. The results show that the articulated reinforcement effectively inhibits the displacement of the slab so that the vertical compressive stress at the bottom of the joint decreases by about 37%; the extreme value variation in the modulus of the surface layer, subgrade layer, and soil base causes the principal stress to decrease by about 0.26%, 5.5%, and 11.6%, respectively; the increase in the thickness of the surface layer and the subgrade layer effectively improves the stress state, with a maximum reduction of 9% and 22%, respectively; Poisson’s ratio and modulus of elasticity of the joint material have a significant effect on the principal stress, and when the material parameters are at the maximum value, the principal stress increases by about 20.8%. In addition, this paper proposes a screening standard for joint material. Finally, it selects 60 mesh rubber-modified asphalt as the optimal joint material. Full article

This article deals with the possibility of using a recycled aggregate from railway ballast and platforms for the production of cement composites with a full or partial replacement of natural aggregates. This study evaluates the physical and mechanical properties of fresh and hardened concrete, as well as its resistance to water pressure, microstructure, and environmental safety. Four concrete recipes using an aggregate at the end of its life cycle from railway ballast (0/25 mm) and from the layers under the asphalt covering of the platforms (0/32 mm) were designed, with a 100% replacement for 0/25, 55% replacement (coarse fraction) for 0/32, and 45% sand for 0/4. The results have shown a significant influence of the type of aggregate on the strength, bulk density, and watertightness of the concrete. At 28 days, the compressive strengths of mixes R250, R400, R250N, and R400N were approximately 8, 20, 30, and 35 MPa, respectively, while after 90 days they increased to 10, 22, 37, and 45 MPa. The corresponding fresh concrete bulk densities ranged from about 1.95 to 2.27 g/cm³, and the water penetration depths ranged between 16 mm (best) and 27 mm (worst) among the mixes. Analyses of aqueous leachates have confirmed that the cement matrix effectively stabilizes the contaminants contained in the recycled aggregate and that the resulting products comply with the legislative limits. This study shows that an aggregate at the end of its life cycle from railway ballast and platforms can be effectively used to produce sustainable cement composites (concrete) with suitable mechanical properties and minimal environmental risks. Full article

The formation of ice on roads is one of the leading causes of winter traffic accidents, resulting in significant social and economic costs. Conventional maintenance techniques, such as salting and mechanical clearance, are costly, environmentally harmful, and not always effective. This paper presents the design, implementation, and pilot validation of a passive geothermal anti-icing system tested at a dedicated experimental facility in Spain. The system consists of copper vertical heat exchangers (1 m depth), a thermal diffusion grid beneath the asphalt layer, and an IoT-based monitoring network using LoRaWAN sensors to capture real-time temperature data at three depths. During the monitoring period, the pilot system showed an increase in subsurface temperature compared to the control section, resulting in a lower likelihood of ice formation on the pavement surface. These findings demonstrate that passive geothermal systems can help improve road safety under winter conditions while reducing energy demand and the use of chemical agents. Future research will focus on optimizing system design, integrating deeper heat exchangers, and assessing large-scale economic feasibility. Full article

This article presents the results of a 10-year research study on the possibilities of implementing circular economy principles into the recovery of construction waste in road construction and paving traffic areas. According to Eurostat, construction waste accounts for approximately 25–30% of the total amount of waste produced in Europe. New legislative policies strongly support selective demolition and recycling with the aim of recycling at least 70% of construction waste. The subject of this research was mixed reclaimed asphalt material (MRAM) composed of 70% asphalt mixture, 10% aggregate, 10% concrete, and 10% soil. Isomorphic models and experimental sections made of MRAM showed that the required characteristics cannot be achieved when using MRAM without heating and compaction. When laying MRAM using a light dynamic plate and additional heating due to solar radiation, the LDD 100 device detected a 53% increase in the deformation modulus. On isomorphic MRAM models, the CBR test showed a 4-, 5-, and 14-times increase in the CBR value when the temperature was increased from 20 °C to 40, 50, and 70 °C. The laboratory results were confirmed by monitoring the surface condition of a local road rehabilitated between 2017 and 2025 using MRAM, where some sections showed the properties of semi-bound layers after eight years. The road surface was improved with a 20 cm layer of MRAM at an air temperature of 30 °C and compacted with a 10-ton smooth roller. The research results presented made it possible to create a proposal for a systematic approach to the evaluation of materials obtained from asphalt roads, optimized on the principles of the circular economy. Full article

Increasing traffic volumes, heavier axle loads, and the growing frequency of premature pavement distress pose major challenges for modern road infrastructure. In many regions, asphalt pavements experience early rutting, cracking, and moisture-induced damage, underscoring the need for improved material performance and longer service life. Reinforcing fibres are increasingly used to enhance asphalt mixture properties, with aramid fibres recognised for their superior mechanical and thermal stability. This study evaluates the effect of FlexForce (FF) fibres on the mechanical and fracture behaviour of two dense-graded asphalt concretes, AC 16 surf and AC 16 bin, produced with different binders and fibre dosages (0.02% and 0.04% by mixture weight). Laboratory tests, including indirect tensile strength ratio (ITSR), indirect tensile stiffness modulus (IT-CY), crack propagation resistance, and dynamic modulus measurements, were performed to assess moisture susceptibility, stiffness, and viscoelastic behaviour. The results showed that fibre addition had little effect on compactability and stiffness under standard conditions but improved temperature stability and stiffness at elevated temperatures, particularly when used with polymer-modified binders. Moisture resistance decreased slightly, while fracture performance improved moderately at intermediate temperatures. Overall, low fibre dosages (~0.02%) provided the most balanced performance, indicating that the mechanical benefits of aramid reinforcement depend strongly on binder rheology, temperature, and interfacial compatibility. These findings contribute to optimising fibre dosage and binder selection for aramid-reinforced asphalt layers in practice. Full article

To quantitatively assess the carbon emission characteristics of expressway construction and to identify its key influencing factors, this study establishes a comprehensive carbon emission accounting framework that covers the material production, transportation, and construction stages based on the life cycle assessment (LCA) approach. Typical expressway projects are selected as case studies to perform stage-based emission quantification and multivariable response analysis. The results indicate that the total carbon emissions per kilometer during the construction phase are approximately 1.80 × 10³ kg CO₂-eq/km, with material production being the dominant contributor, accounting for about 60–70%, followed by transportation and construction activities. The analysis of structural layers shows that variations in the thickness of the asphalt surface and cement-stabilized base layers, which are the main sources of emissions, are strongly and positively correlated with total emissions, making them the principal control factors. Transportation distance and equipment efficiency are identified as moderately sensitive parameters, each contributing approximately 3–5% to emission variation. Further multivariable response analysis demonstrates nonlinear coupling effects between structural parameters and transportation factors. The combined increase in layer thickness and transport distance significantly amplifies total emissions, while the marginal impact of long-distance transport gradually decreases. Based on these findings, this study proposes a low-carbon construction strategy that focuses on structural optimization, local material sourcing, energy-efficient construction practices, and the use of clean energy. The outcomes of this research provide a theoretical foundation and quantitative reference for carbon emission prediction, structural design optimization, and green construction decision making during the expressway construction phase. Full article

This study investigates the performance of mineral–cement–emulsion (MCE) mixtures produced with reclaimed asphalt pavement (RAP) and recycled mineral aggregates for use in road base layers. The aim was to evaluate the mechanical properties, field performance, and key factors influencing the cracking behavior of these sustainable cold-recycled mixtures. Approximately 160 laboratory tests were performed to determine indirect tensile strength (ITS), stiffness modulus (IT-CY), bulk density, and air-void content. The MCE mixture achieved an average ITS of 1.09 MPa and stiffness modulus of 5873 MPa after 28 days of curing, confirming compliance with design requirements. The field investigation of a test section showed good structural integrity and compaction, although several transverse cracks developed during the first year of service. The mechanistic interpretation attributed these cracks to combined cement hydration shrinkage and thermal contraction effects. The results indicate that MCE mixtures made with recycled materials can meet technical specifications while reducing environmental impact, provided that binder proportions and curing conditions are carefully optimized. Full article

The tensile behavior of cold recycled cement-treated mixtures (CRCTMs), typically produced through full-depth reclamation (FDR), is critical for pavement design. Since no universal design method exists, different tests are applied, leading to varying results. In this context, this study aimed (a) to statistically analyze the flexural tensile strength (FTS) and indirect tensile strength (ITS) of CRCTMs incorporating reclaimed asphalt pavement (RAP) and lateritic soil (LS); (b) to evaluate how using FTS or ITS influences the design of CRCTM layers. FTS and ITS tests were conducted with different cement (1–7%) and RAP (7–93%) contents at multiple curing times (3–28 days), and results were used for statistical and mechanistic analyses. Results showed that cement and RAP contents significantly increased FTS and ITS. RAP exhibited the strongest influence on ITS. This indicates that CRCTMs with similar materials benefit from higher RAP contents. Mechanistic analysis revealed that lower RAP contents require thicker pavement structures, suggesting that increasing RAP can reduce costs and environmental impacts. FTS was about 65% higher than ITS, but using ITS in design led to structures 1.7–3.3 times thicker for the same service life. These findings highlight the need for proper CRCTM characterization, with flexural tests recommended for more reliable and cost-effective pavement design. Full article