Search Results (386)

Several variables influence the performance of hot asphalt mixtures including reclaimed asphalt pavement (RAP). Among these, the virgin bitumen’s origin, the mix production temperature and the time the mix is kept at a high temperature between mixing and compaction play a fundamental role but are often neglected. This study aimed to quantify the negative effects associated with the improper choice of these variables. Therefore, their influence on the mechanical (indirect tensile stiffness modulus and strength, Cracking Tolerance Index) and chemical (Fourier Transform Infra-Red spectroscopy) characteristics of asphalt mixtures containing 50% RA were investigated. In particular, two rejuvenators, two types of virgin bitumen (visbreaker and straight-run), two production temperatures (140 °C and 170 °C) and three conditioning times in the oven (30 min, 90 min and 180 min) were analyzed. The results showed interesting findings that allow us to recommend selecting the virgin bitumen type carefully and to avoid excessively stressing the binder during the production of the mix. Full article

Quality requirements for mineral aggregate for concrete used to construct pavement for busy highways are high because of the fatigue traffic loads and environmental exposure. The use of local aggregate for infrastructure projects could result in important sustainability improvements, provided that the concrete’s durability is assured. The objective of this study was to identify the potential alkaline reactivity of local greywacke aggregate and select appropriate mitigation measures against the alkali–silica reaction. Experimental tests on concrete specimens were performed using the miniature concrete prism test at 60 °C. Mixtures of coarse greywacke aggregate up to 12.5 mm with natural fine aggregate of different potential reactivity were evaluated in respect to the expansion, compressive strength, and elastic modulus of the concrete. Two preventive measures were studied—the use of metakaolin and slag-blended cement. A moderate reactivity potential of the greywacke aggregate was found, and the influence of reactive quartz sand on the expansion and instability of the mechanical properties of concrete was evaluated. Both crystalline and amorphous alkali–silica reaction products were detected in the cracks of the greywacke aggregate. Efficient expansion mitigation was obtained for the replacement of 15% of Portland cement by metakaolin or the use of CEM III/A cement with the slag content of 52%, even if greywacke aggregate was blended with moderately reactive quartz sand. It resulted in a relative reduction in expansion by 85–96%. The elastic modulus deterioration was less than 10%, confirming an increased stability of the elastic properties of concrete. Full article

Semi-flexible pavement (SFP) is a durable and cost-effective alternative to conventional rigid and flexible pavement and is formed by permeating an open-graded asphalt (OGA) layer with high-fluidity cement grout. The degradation of SFP mattresses due to fuel oil spills can result in significant maintenance costs. Incorporating glass waste (GW) into the construction of SFPs offers an eco-friendly solution, helping to reduce repair costs and environmental impact by conserving natural resources and minimizing landfill waste. The main objective of this research is to investigate the mechanical performance and fuel oil resistance of SFP composites containing different levels of glass aggregate (GlaSFlex composites). Fine glass aggregate (FGA) was replaced with fine virgin aggregate at levels of 0%, 20%, 40%, 60%, 80%, and 100% by mass. The results indicated the feasibility of utilizing FGA as a total replacement (100%) for fine aggregate in the OGA structural layer of SFPs. At 100% FGA, the composite exhibited excellent mechanical performance and durability, including a compressive strength of 8.93 MPa, a Marshall stability exceeding 38 kN, and a stiffness modulus of 19,091 MPa. Furthermore, the composite demonstrated minimal permanent deformation (0.04 mm), a high residual stability of 94.7%, a residual compressive strength of 83.3%, and strong resistance to fuel spillage with a mass loss rate of less than 1%, indicating excellent durability. Full article

The conflicting demands of urban trees and walkable surfaces result in significant financial burdens for municipal administrators who understand that urban residents want tree-lined walkable surfaces. This study investigates three methodologies for mitigating this tension: suspended grating systems, modular box systems, and structural soils. A Multi-Criteria Analysis (MCA) was conducted to evaluate their suitability in dense urban areas, employing criteria categorized into Environmental, Economical, and Other considerations. The comparison focused on critical aspects such as the impact on tree health (root growth, water availability), installation complexity, initial costs, and overall suitability for diverse urban contexts. The MCA indicates that, under the given weighting of criteria, suspended grating systems (especially those suited for existing trees) rank the highest, primarily due to their superior root protection and minimal disturbance to established root systems. In contrast, modular box systems and structural soils emerge as particularly strong contenders for new tree plantings. Structural soils may have application at sites with existing trees, but the costs of removing native soil are a consideration. Sensitivity analysis suggests that modular box systems may become the preferred option when greater emphasis is placed on stormwater management and new plantings, rather than on challenges for existing trees or underground infrastructure. Structural soils score well in cost-effectiveness and installation speed but require careful implementation to address their lower root protection performance and long-term maintenance concerns. Ultimately, the optimal solution depends on unique site-specific conditions and budgetary constraints, emphasizing the necessity of tailored approaches to balance urban infrastructure with tree health. Full article

The effects of heavy traffic and complex natural environmental conditions have made the problem of the inadequate life expectancy of asphalt pavements increasingly pronounced. In this study, finite-element software was used to establish the three-dimensional analytical model of temperature-load coupling under different axial loads and calculate the distribution law of temperature-load coupling stress under the most unfavorable loading conditions. By comparing temperature and coupled stresses at different depths, the extent to which combined stress changes due to environmental factors affect different depths was determined. Finally, the fatigue life patterns of asphalt pavements under different seasons and axle loads were analyzed. The results showed that the temperature-load coupling stress varied periodically under different axial loads. Among them, the temperature stress had less influence on the coupling stress in spring and fall and more influence in winter. As the depth increases, the coupling stresses and their range of influence gradually decrease. Also, the farther away from the wheel load position, the smaller the traveling load disturbance and the closer the coupling stresses were to the temperature stresses. Under the most unfavorable loading conditions, the change rule of the degree of influence of environmental effects along the depth direction showed that the winter gradually decreased, the spring and fall seasons for the first time decreased and then increased, and the minimum influence on the road surface was at 9 cm. Overall, the degree of influence of environmental action at different axial loads was 70.53%, 41.90%, 27.13%, and 23.77% along the depth direction. Full article

Urbanization and climate change have disrupted natural water circulation by increasing impervious surfaces and altering rainfall patterns, leading to reduced groundwater infiltration, deteriorating water quality, and heightened flood risks. This study investigates the application of Low Impact Development (LID) and flood control facilities as structural measures to address these challenges in the upper watershed of the Fucha River in Bogotá, Colombia. The methodology involved analyzing watershed characteristics, defining circulation problems, setting hydrological targets, selecting facility types and locations, evaluating performance, and conducting an economic analysis. To manage the target rainfall of $26.5$$\mathrm{m}$$\mathrm{m}$ under normal conditions, LID facilities such as vegetated swales, rain gardens, infiltration channels, and porous pavements were applied, managing approximately 2362 ${\mathrm{m}}^3$ of runoff. For flood control, five detention tanks were proposed, resulting in a 31.8% reduction in peak flow and a 7.3% decrease in total runoff volume. The flooded area downstream was reduced by $46.8$$\mathrm{h}\mathrm{a}$, and the benefit–cost ratio was calculated at 1.02. These findings confirm that strategic application of LID and detention facilities can contribute to effective urban water cycle management and disaster risk reduction. While the current disaster management approach in Bogotá primarily focuses on post-event response, this study highlights the necessity of transitioning toward proactive disaster preparedness. In particular, the introduction and expansion of flood forecasting and warning systems are recommended as non-structural measures, especially in urban areas with complex infrastructure and climate-sensitive hydrology. Full article

The rapid expansion of urban areas has increased the prevalence of impermeable surfaces, intensifying flooding risks by disrupting natural water infiltration. Permeable pavements have emerged as a sustainable alternative, capable of reducing stormwater runoff, improving surface friction, and mitigating urban heat island effects. Nevertheless, their broader implementation is often hindered by issues such as clogging and limited mechanical strength resulting from high porosity. This study examines the design of interlocking permeable blocks utilizing ultra-high-performance concrete (UHPC) to strike a balance between enhanced drainage capacity and high structural performance. A topology optimization (TO) strategy was applied to numerically model the ideal block geometry, incorporating 105 drainage channels with a diameter of 6 mm—chosen to ensure manufacturability and structural integrity. The UHPC formulation was developed using particle packing optimization with ordinary Portland cement (OPC), silica fume, and limestone filler to reduce binder content while achieving superior strength and workability, guided by rheological assessments. Experimental tests revealed that the perforated UHPC blocks reached compressive strengths of 87.8 MPa at 7 days and 101.0 MPa at 28 days, whereas the solid UHPC blocks achieved compressive strengths of 125.8 MPa and 146.2 MPa, respectively. In contrast, commercial permeable concrete blocks reached only 28.9 MPa at 28 days. Despite a reduction of approximately 30.9% in strength due to perforations, the UHPC-105holes blocks still far exceed the 41 MPa threshold required for certain structural applications. These results highlight the mechanical superiority of the UHPC blocks and confirm their viability for structural use even with enhanced permeability features. The present research emphasizes mechanical and structural performance, while future work will address hydraulic conductivity and anticlogging behavior. Overall, the findings support the use of topology-optimized UHPC permeable blocks as a resilient solution for sustainable urban drainage systems, combining durability, strength, and environmental performance. Full article

The structural integrity of cement concrete pavements, paramount for ensuring traffic safety and operational efficiency, faces mounting challenges from the escalating burden of heavy-duty vehicular traffic. Precise characterisation of pavement dynamic responses under such conditions proves indispensable for implementing effective structural health monitoring and early warning system deployment. This investigation examines the triaxial dynamic response characteristics of cement concrete pavement subjected to low-speed, heavy-duty vehicular excitations, employing data acquired through in situ field measurements. A monitoring system incorporating embedded triaxial MEMS accelerometers was developed to capture vibration signals directly within the pavement structure. Raw data underwent preprocessing utilising a smoothing wavelet transform technique to attenuate noise, followed by empirical mode decomposition (EMD) and short-time energy (STE) analysis to scrutinise the time–frequency and energetic properties of triaxial vibration signals. The findings demonstrate that heavy, slow-moving vehicles generate substantial triaxial vibrations, with the vertical (Z-axis) response exhibiting the greatest amplitude and encompassing higher dominant frequency components compared to the horizontal (X and Y) axes. EMD successfully decomposed the complex signals into discrete intrinsic mode functions (IMFs), identifying high-frequency components (IMF1–IMF3) associated with transient vehicular impacts, mid-frequency components (IMF4–IMF6) presumably linked to structural and vehicle dynamics, and low-frequency components (IMF7–IMF9) representing system trends or ambient noise. The STE analysis of the selected IMFs elucidated the transient nature of axle loading, revealing pronounced, localised energy peaks. These findings furnish a comprehensive understanding of the dynamic behaviour of cement concrete pavements under heavy vehicle loads and establish a robust methodological framework for pavement performance assessment and refined axle load identification. Full article

Aiming at the problems of serious pavement temperature diseases, low efficiency and high loss of ice-breaking methods, high occupancy rate of waste tires and the low utilization rate and insufficient durability of rubber particles, this paper aims to improve the service level of roads and ensure the safety of winter pavements. A pavement material with high efficiency, low carbon and environmental friendliness for active snow melting and ice breaking is developed. Firstly, NaOH, NaClO and KH550 were used to optimize the treatment of rubber particles. The hydrophilic properties, surface morphology and phase composition of rubber particles before and after optimization were studied, and the optimal treatment method of rubber particles was determined. Then, the optimized rubber particles were used to replace the natural aggregate in the polyurethane gel mixture by the volume substitution method, and the optimum polyurethane gel dosages and molding and curing processes were determined. Finally, the influence law of the road performance of RPGM was compared and analyzed by means of an indoor test, and the ice-breaking effect of RPGM was explored. The results showed that the contact angles of rubber particles treated with three solutions were reduced by 22.5%, 30.2% and 36.7%, respectively. The surface energy was improved, the element types on the surface of rubber particles were reduced and the surface impurities were effectively removed. Among them, the improvement effect of the KH550 solution was the most significant. With the increase in rubber particle content from 0% to 15%, the dynamic stability of the mixture gradually increases, with a maximum increase of 23.5%. The maximum bending strain increases with the increase in its content. The residual stability increases first and then decreases with the increase in rubber particle content, and the increase ranges are 1.4%, 3.3% and 0.5%, respectively. The anti-scattering performance increases with the increase in rubber content, and an excessive amount will lead to an increase in the scattering loss rate, but it can still be maintained below 5%. The fatigue life of polyurethane gel mixtures with 0%, 5%, 10% and 15% rubber particles is 2.9 times, 3.8 times, 4.3 times and 4.0 times higher than that of the AC-13 asphalt mixture, respectively, showing excellent anti-fatigue performance. The friction coefficient of the mixture increases with an increase in the rubber particle content, which can be increased by 22.3% compared with the ordinary asphalt mixture. RPGM shows better de-icing performance than traditional asphalt mixtures, and with an increase in rubber particle content, the ice-breaking ability is effectively improved. When the thickness of the ice layer exceeds 9 mm, the ice-breaking ability of the mixture is significantly weakened. Mainly through the synergistic effect of stress coupling, thermal effect and interface failure, the bonding performance of the ice–pavement interface is weakened under the action of driving load cycle, and the ice layer is loosened, broken and peeled off, achieving efficient de-icing. Full article

The use of Reclaimed Asphalt Pavement (RAP) is a sustainable strategy to conserve natural resources, reduce environmental pollution, and lower construction costs. However, aged asphalt in RAP suffers from oxidation and loss of light fractions, increasing stiffness and brittleness. A key scientific challenge is how to effectively restore the performance of aged asphalt while maintaining cost efficiency. In this study, a novel asphalt rejuvenator was developed to address this issue. The rejuvenator consists of 6% aromatic oil-like materials to replenish light components, 1.52% plasticizer to enhance ductility, and 0.3% modifier A to improve adhesion, with a total dosage of 7.82% by the mass of the aged binder. The rejuvenator meets the requirements of Chinese specifications. The performance evaluation was conducted at both asphalt binder and mixture scales. The results show that the rejuvenator significantly improves low-temperature cracking resistance and medium-temperature fatigue performance of aged binders, although it slightly reduces high-temperature rutting resistance. When applied to asphalt mixtures with 45% RAP, the rejuvenated mixtures exhibited enhanced low-temperature performance. A comparative analysis with commercial rejuvenators confirmed the developed product’s competitive performance and economic benefit. This study provides technical insight into rejuvenator design and addresses critical challenges in RAP recycling for sustainable pavement engineering. Full article

Coal bottom ash (CBA) is a waste produced by burning coal that presents possible hazards to human well-being and the environment. Rapid economic expansion has increased the utilisation of CBA, resulting in a crisis concerning the disposal of this waste. By employing waste as a replacement for natural materials, it is possible to achieve sustainable and environmentally friendly construction. This study assesses the effects of utilising CBA waste as a replacement for fine aggregate in stone mastic asphalt (SMA) pavement. Seven asphalt mixture proportions were designed, each of which employed a different percentage of CBA (0%, 10%, 20%, 30%, 50%, 70%, and 100%) as a fine aggregate replacement. The performance tests conducted in this research were the Cantabro durability test, resilient modulus test, dynamic creep test, and moisture susceptibility test. The findings showed an improvement in the durability and resistance to permanent deformation of the SMA mixtures with 30% and 50% CBA replacement, respectively. However, further increases in the CBA content caused a decrease in the durability and resistance to permanent deformation. Meanwhile, the stiffness and tensile strength ratio (TSR) value decrease with the use of CBA replacement at any percentage. However, the TSR value of the SMA mixtures with 50% or less CBA replacement was more than 80%, which meets the minimum requirement set by JKR. In conclusion, incorporating CBA into SMA mixture has a positive effect on certain mechanical properties, particularly its durability and resistance to permanent deformation at optimal replacement levels, highlighting its potential to be used as a sustainable material in asphalt pavement construction. Full article

Asphalt binder aging under natural exposure critically determines pavement durability, though current research inadequately captured performance evolution across diverse regional climates. This study investigated climate-driven degradation mechanisms through 12-month all-weather aging (AWA) tests in Gansu, Shandong, and Beijing via rheological (G-R parameter, stiffness modulus S-value) and chemical analyses (carbonyl index I_C=O, sulfoxide index I_S=O). The results demonstrated significant region-dependent aging disparities beyond laboratory simulation. In Gansu, extreme thermal fluctuations and UV radiation accelerated hardening via thermal stress cycles and photo-oxidation, yielding 52.4% higher G-R parameter than PAV. In Shandong, humid saline environments triggered sulfur oxidation-driven electrochemical corrosion, increasing I_S=O by 4.2% compared to PAV. In Beijing, synergistic UV–thermal oxidation elevated I_C=O and S-value by 8% and 40.7%, respectively versus PAV. Critically, I_C=O exhibited strong positive correlations with rheological degradation across regions (r > 0.90, p < 0.01). Based on I_C=O, the 12-month all-weather aging rate in Beijing exceeded Gansu and Shandong by 18.5% and 68%, revealing UV–thermal coupling as the most severe degradation pattern. Novelty lies in quantifying region-specific multi-factor coupling effects (UV–thermal, hygrothermal–salt, etc.) and demonstrating their superior severity over PAV (Beijing > Gansu > Shandong). Dominant environmental factors showed distinct regional variations: UV radiation and temperature difference dominated in Gansu (I_C=O, r = 0.76) and Beijing (0.74), while precipitation—I_C=O correlation prevailed in Shandong (0.76), yet multi-factor coupling ultimately governed aging. These findings provide theoretical foundations for region-tailored and climate-resilient asphalt pavement design. Full article

Resource depletion and environmental degradation have resulted from the substantial increase in the use of natural aggregates and construction materials brought on by the growing demand for infrastructure development. Road building using mining waste has become a viable substitute that reduces the buildup of industrial waste while providing ecological and economic advantages. In order to assess the appropriateness of several mining waste materials for use in road building, this study investigates their engineering characteristics. These materials include slag, fly ash, tailings, waste rock, and overburden. To ensure long-term performance in pavement applications, this study evaluates their tensile and compressive strength, resistance to abrasion, durability under freeze–thaw cycles, and chemical stability. This review highlights the potential of mining waste materials as sustainable alternatives in road construction. Waste rock and slag exhibit excellent mechanical strength and durability, making them suitable for high-traffic pavements. Although fly ash and tailings require stabilization, their pozzolanic properties enhance subgrade reinforcement and soil stabilization. Properly processed overburden materials are viable for subbase and embankment applications. By promoting the reuse of mining waste, this study supports landfill reduction, carbon emission mitigation, and circular economy principles. Overall, mining byproducts present a cost-effective and environmentally responsible alternative to conventional construction materials. To support broader implementation, further efforts are needed to improve stabilization techniques, monitor long-term field performance, and establish effective policy frameworks. Full article

The vehicle scanning method (VSM) is widely used for bridge damage identification (BDI) because it relies solely on vehicle dynamic responses. The recently introduced contact point response, which is derived from vehicle dynamics but devoid of vehicle-related natural frequencies, shows great potential for application in the vehicle scanning method. However, its application in bridge damage detection remains understudied. The aim of this paper is to propose a new bridge damage identification method based on the contact point response. The method uses variational modal decomposition (VMD) to solve the problem of mode mixing and spurious frequencies in the signal. The continuous wavelet transform (CWT) is then utilized for damage identification. The introduction of variational modal decomposition makes the extracted signal more accurate, thus enabling more accurate damage identification. Numerical simulations validate the method’s robustness under varying conditions, including the vehicle speed, wavelet scale factors, the number of bridge spans, and pavement roughness. The results demonstrate that variational modal decomposition eliminates signal artifacts, producing smooth variational modal decomposition–continuous wavelet transform curves for accurate damage detection. In this study, we offer a robust and practical solution for bridge health monitoring using the vehicle scanning method. Full article

The integration of Recycled Concrete Aggregate (RCA) and Reclaimed Asphalt Pavement (RAP) into Hot Mix Asphalt (HMA) presents a sustainable solution to mitigate environmental impacts and reduce reliance on virgin materials. This study investigates the influence of RCA and RAP as partial replacements for natural limestone aggregates on the volumetric, mechanical, and performance properties of asphalt mixtures. Replacement levels of 11%, 33%, and 66% (by total aggregate weight) were evaluated through comprehensive testing, including dynamic modulus, flow number, stiffness factor, and loss modulus assessments under varying temperatures and loading frequencies. Findings indicate that recycled aggregate incorporation results in a progressive reduction in optimum asphalt binder content, voids in mineral aggregates (VMAs), and voids filled with asphalt (VFAs). While all mixtures demonstrated acceptable stiffness-frequency behavior, the 33% replacement mix provided the best balance of rutting resistance and fatigue performance, satisfying Superpave volumetric criteria. The 11% mix exhibited enhanced fatigue resistance, whereas the 66% mix, despite showing the highest rutting stiffness, failed to meet minimum volumetric thresholds and is therefore unsuitable for structural applications. Statistical analysis (one-way ANOVA) confirmed the significant effect of RCA and RAP content on the mechanical response across performance zones. The results highlight the potential of using moderate recycled aggregate levels (particularly 33%) to produce durable, sustainable, and cost-efficient asphalt mixtures. For regions with mixed distress conditions, a 33% replacement is recommended, while 11% may be preferable in fatigue-critical environments. Further research incorporating viscoelastic continuum damage models and life cycle cost analysis is suggested to optimize design strategies and quantify long-term benefits. Full article