Search Results (135)

Conventional PMSs often rely on static age-based assumptions, which can fail to capture nonlinear, state-dependent deterioration and improvement-like responses observed in long-term monitoring data. This study addresses these limitations by proposing a reaction-oriented analytical framework using eight years of Korea Highway PMS data (2015–2022). We construct a Δ–State Vector by combining the previous-year condition grade with noise-filtered annual changes in the International Roughness Index (IRI) and Rut Depth (RD). Measurement noise is separated from structural signals via MAD-based noise bands (ΔIRI: ±0.089 m/km; ΔRD: ±0.993 mm), with a global MAD floor (minimum-threshold constraint) to avoid degenerate zero-band cases under sparse or near-constant transitions. The resulting vectors are embedded into a low-dimensional Reaction Space using UMAP and clustered with HDBSCAN. To validate interpretability, a rule-based Trend × Mode Reaction Signature taxonomy is used to assess the semantic consistency of unsupervised clusters. Five dominant reaction regimes are identified, showing strong agreement with signature-based labels (weighted purity = 0.927; coverage for purity ≥ 0.60 = 0.911). Overall, the results indicate that deterioration dynamics are governed by lane–segment heterogeneity and prior-state dependence rather than chronological age, providing a reproducible foundation for future event-sensitive, dynamic age reset frameworks. Full article

The growing use of reclaimed asphalt pavement (RAP) in warm-mix asphalt (WMA) presents significant challenges when RAP originates from aged polymer-modified binder (PMB) pavements, where severe oxidation and polymer degradation lead to excessive stiffness and poor cracking resistance. This study presents a multi-scale evaluation of a hybrid modification strategy combining recycled engine oil waste (REOW, 3 wt.%) and styrene–butadiene–styrene (SBS, 1–4 wt.%) to restore aged PMB-containing RAP systems under controlled binder conditions. Three binders (control, REOW-modified, and REOW–SBS hybrid) were prepared using a fixed 70/30 virgin-to-RAP binder blend and characterized through rheological analysis, and multiple stress creep recovery (MSCR). The findings show that REOW softened the binder but reduced elastic recovery, whereas SBS modification restored elastic response. Corresponding WMA mixtures with 30 wt.% RAP and 5.0 wt.% total binder content were evaluated for moisture damage, raveling, rutting, and cracking resistance. At the mixture scale, the hybrid system achieved a TSR of 83%, reduced Hamburg rut depth by ~20%, and increased SCB fracture energy by ~30% compared with the control. These findings demonstrate that combined rejuvenation–reinforcement effectively re-mobilizes aged PMB chemistry and restores polymer elasticity, enabling high-performance WMA production with RAP derived from polymer-modified pavements. Full article

Background: Winch-assisted harvesting is an alternative to traditional cable yarding on steep slopes, offering improved operational efficiency and fewer limitations. Knowledge on the effects of winch-assisted harvesting on soil disturbance are limited. This study aimed to assess the effects of winch-assisted and conventional tracked harvester operations on soil compaction and machine slippage in a clear-cut stand with sandy loam soil. Methods: We evaluated changes in soil physical properties, in depth and extent, along machine operating corridors with and without winch-assist across slope gradients ranging from 30% to 52% and up to three machine passes. Results: The relative increase in bulk density differed between treatments. In the non-assisted corridors, the bulk density increased by 18%, 12%, and 11% at depths of 0–10, 10–20, and 20–30 cm, respectively; the winch-assisted corridors showed smaller increases of 12%, 5%, and 3% at the corresponding depths. The winch-assisted plots did not show a significant reduction in rut depth compared with the non-assisted plots, a result likely influenced by site-specific dry soil conditions. Conclusions: These results highlight the potential of winch-assisted systems to reduce horizontal soil disturbance, though their effectiveness in limiting rutting remains variable under dry conditions. Full article

The utilization of agro-byproducts for textile dyeing and finishing is strongly suggested to meet sustainability and cost-efficiency objectives. Despite recently proliferating studies, three major issues hinder the industrialization of such a technique: identifying reasonable bio-resources, ensuring compatibility between agro-byproducts and textile substrates, and achieving satisfactory color depth, functionality, and durability. This research introduces an approach that forms and fixes silver nanoparticles (AgNPs) on silk using three representative flavonoids (FLs)—Quercetin (QUE), Baicalin (BAI), and Rutin (RUT)—through a single-step in situ bio-reduction. Results demonstrate that FLs-synthesized AgNPs@silk generates attractive spectra of hues, varying from pale cream-brown to deep golden-brown. Using an equivalent quantity of FLs, the color intensity of silk descends in QUE-Ag@silk > BAI-Ag@silk > RUR-Ag@silk, due to the decreasing reactivity and binding affinity of FLs to silk. SEM reveals uniformly distributed spherical AgNPs in dimensions between 20 and 40 nm on silk and the dimension inversely correlates with FLs concentration while being directly proportional to silver nitrate. The modified silk exhibits remarkable antimicrobial performance (>98% pathogen elimination) and exceptional wash resistance (>90% reduction both of E. coli and S. aureus after ten cycles of washing). Additionally, the FLs-synthesized AgNPs provide silk with superior UV shielding capability. This study stems from environmental awareness and sustainable production of AgNPs by FLs, ready for developing hygienic and therapeutic textile materials. Full article

This study evaluated the combined incorporation of zinc oxide (ZnO) and titanium dioxide (TiO₂) nanoparticles into a styrene–butadiene–styrene (SBS) copolymer-modified asphalt binder, aiming to increase thermal conductivity and healing potential while maintaining rheological performance. Nanocomposites containing ZnO + TiO₂ (50/50 wt.%) were produced at dosages of 2–12 wt.% and subjected to the Rolling Thin Film Oven Test (RTFOT), thermal conductivity measurements, viscosity testing, and rheological characterization. A dense-graded asphalt mixture with the optimized dosage was evaluated through wheel-tracking, four-point bending fatigue and healing, and internal heating rate assessment under microwave radiation. The integrated results indicated 8.5 wt.% as the optimal dosage, providing a 106.3% increase in thermal conductivity and improving the high-temperature performance grade (PGH) from 76-XX to 82-XX. Non-recoverable creep compliance (Jnr) decreased by 21.1%, and viscosity at 135 °C increased by 41.8%, remaining below 3.0 Pa·s. In the asphalt mixture, healing capacity increased by 50.7%, and the internal heating rate by 50.0%, while the wheel-tracking rut depth decreased by 13.3%. These findings demonstrate that 8.5 wt.% ZnO + TiO₂ simultaneously enhances heat conduction, healing efficiency, and resistance to permanent deformation, offering a promising solution for pavements subjected to high temperatures and heavy traffic. Full article

Flexible pavements using conventional bitumen are prone to suffering severe distress in hot climates, particularly rutting and moisture-induced damage. This study explores synergistic effects of waste-derived High-Density Polyethylene (HDPE) and Bakelite as dual modifiers for asphalt mixtures under Pakistan’s extreme climate, where summer temperatures exceed 45 °C. Modified mixtures were prepared via wet process using HDPE (3%, 6%, 9% by weight of optimum bitumen content) combined with 6% Bakelite, evaluated against control mixtures (60/70 bitumen, NHA Class-B gradation). Performance assessment included indirect tensile strength, moisture susceptibility (TSR), resilient modulus, and Hamburg wheel tracking tests. The optimal 6%HDPE + 6%Bakelite formulation achieved remarkable improvements over control: 24.7% higher dry ITS (0.647 MPa), 48.7% higher conditioned ITS (0.617 MPa), 95.36% TSR (19% above specifications), 43.7% greater resilient modulus (4866 MPa), and 27.4% lower rutting depth (2.38 mm). These enhancements are likely associated with the development of a stiffer polymer resin network between HDPE and rigid Bakelite particles, which appears to provide a favorable balance between mixture flexibility and stiffness. At 9% HDPE, performance degradation in strength and moisture-related properties suggests possible phase separation, although rutting resistance continued improving. This dual-modification strategy provides sustainable, cost-effective enhancement of pavement durability in hot climates while addressing waste management challenges, offering significant potential for reducing maintenance costs and extending service life. Full article

The current global economic challenges and resource scarcity necessitate the development of cost-effective and sustainable pavement solutions. This study investigates the performance of asphalt mixtures modified with Low-Density Polyethylene (LDPE) and Styrene–Butadiene–Styrene (SBS) as binder modifiers, and Hydrated Lime (Ca(OH)₂) and Reclaimed Asphalt Pavement (RAP) as aggregate replacements. The research aims to optimize the combination of these materials for enhancing the durability, sustainability, and mechanical properties of asphalt mixtures under various climatic and traffic conditions. Asphalt mixtures were modified with 5% LDPE and 2–6% SBS (by bitumen weight), with 2% Hydrated Lime and 15% RAP added to the mix. The performance of these mixtures was evaluated using the Simple Performance Tester (SPT), focusing on rutting, cracking, and fatigue resistance at varying temperatures and loading frequencies. The NCHRP 09-29 Master Solver was employed to generate master curves for input into the AASHTOWare Mechanistic-Empirical Pavement Design Guide (MEPDG), allowing for an in-depth analysis of the modified mixes under different traffic and climatic conditions. Results indicated that the mix containing 5% LDPE, 2% SBS, 2% Hydrated Lime, and 15% RAP achieved the best performance, reducing rutting, fatigue cracking, and the International Roughness Index (IRI), and improving overall pavement durability. The combination of these modifiers showed enhanced moisture resistance, high-temperature rutting resistance, and improved dynamic modulus. Notably, the study revealed that in warm climates, thicker pavements with this optimal mix exhibited reduced permanent deformation and better fatigue resistance, while in cold climates, the inclusion of 2% SBS further improved the mix’s low-temperature performance. The findings suggest that the incorporation of LDPE, SBS, Hydrated Lime, and RAP offers a sustainable and cost-effective solution for improving the mechanical properties and lifespan of asphalt pavements. Full article

In order to accurately characterize the temperature dependence of the high-temperature performance of asphalt pavement surface layer materials, this paper studies the effects of temperature, load, and number of actions on the high-temperature anti-rutting performance of asphalt pavement surface layer materials (AC-13 and AC-16 mixtures), based on indoor rutting tests, and constructs a high-temperature performance temperature-dependent model and rutting prediction model for surface layer materials. The results show that as the temperature increases, the dynamic stability of the mixture decreases in an S-shaped curve, and the rut depth increases exponentially. The temperature-dependent model transition temperatures for the dynamic stability of 70#, 50#, 30#, SBS, and HMB asphalt mixtures are 39 °C, 44 °C, 46 °C, 56 °C, and 56 °C, respectively. The dynamic stability of modified asphalt mixtures is significantly higher than that of base asphalt mixtures. The depth of wheel ruts is affected by temperature, load, and the number of actions. The variation ranges of the load index k_P, the temperature index k_T, and the number of actions index k_N are 0.727–1.222, 1.926–2.177, and 0.133–0.295, respectively. The correlation coefficients of the wheel rut prediction model are all above 0.95, and the depth of wheel ruts can be predicted by the model. Full article

Lava caves commonly occur in basaltic ground and can compromise roadway stability when present beneath pavements; however, their long-term effects remain insufficiently characterized. This study quantitatively evaluates how lava caves influence pavement behavior using numerical analyses in ABAQUS/CAE. The parameters examined include the presence/absence of a cave, cave width, cover depth, pavement thickness, and load range. Load–settlement curves under a uniformly distributed surface load show that narrower load ranges concentrate stresses and produce larger settlements, whereas wider load ranges disperse stresses and reduce deformation. Classification of deformation behavior using a rutting criterion indicates that plastic soil response dominates under most conditions. A Peak Load Reduction (PLR) index further demonstrates that structural resistance decreases markedly with shallow cover, larger cave width, and narrower load range. Overall, pavement stability above lava caves is governed primarily by cover depth, load range, and cave width, while the effect of pavement thickness is negligible. These findings suggest that, in basaltic terrains, design and maintenance should prioritize subsurface conditions and loading characteristics over pavement thickness. Full article

Aiming at the problems of excessive soil disturbance caused by deep plowing and stripped straw backfilling in strip tillage machinery, which are induced by the large amount of residual straw before maize sowing in the Huang-Huai-Hai Region, an integrated tillage machine suitable for pre-sowing strip tillage of summer maize—integrating subsoiling, stubble-crushing, and soil-guiding functions—was designed. First, the physical properties of straw were analyzed to determine the tooth profile parameters of the stubble-crushing wheel. The unique convex structure of the tooth disc enables it to simultaneously perform depth-limiting and soil-pressing functions. By calculating the flow characteristics of soil during tillage, the angle and distance between the subsoiling shovel and the stubble-crushing wheel were designed. This not only enhances soil crushing and flow but also reduces the occurrence of blockages. A discrete element simulation test with quadratic orthogonal rotation combination was conducted. The machine’s forward speed, wheel position distance, and wheel deflection angle were selected as test factors to analyze their effects on the soil loss rate of the seedbed strip and straw backflow effect under different combinations. The optimal combination of parameters was determined as follows: forward speed of 7.383 km/h, front–rear position distance parameter of −10.131 cm, and deflection angle of 8.608°, with the soil loss rate of the seedling belt reaching 5.486% under this condition. Field experiments were conducted in combination with the strip tiller to verify the simulation-optimized parameters, and comparative experiments at different speeds were also carried out. The field experimental results showed that the deviation of the actual soil disturbance rate caused by the machine from the simulated value was −1.166%, and the soil disturbance rate within the seedling belt was even lower. The results indicated that after the operation of the improved machine, there were no obvious ruts on the soil surface, and the straw was evenly distributed at the edge of the seedling belt, which meets the agronomic requirements for maize planting. Full article

Rehabilitation plans are based on pavement condition assessments, which are crucial to modern pavement management systems. However, some of the disadvantages of conventional approaches for road maintenance and repair include the time consumption, high costs, visual errors, seasonal limitations, and low accuracy. Continuous and efficient pavement monitoring is essential, necessitating reliable equipment that can function in a variety of weather and traffic conditions. UAVs offer a practical and eco-friendly alternative for tasks including road inspections, dam monitoring, and the production of 3D ground models and orthophotos. They are more affordable, accessible, and safe than traditional field surveys, and they reduce the environmental effects of pavement management by using less fuel and producing less greenhouse gas emissions. This study uses UAV technology in conjunction with ground control points (GCPs) to assess the kind and amount of damage in flexible pavements. Vertical photogrammetric mapping was utilized to produce 3D road models, which were then processed and analyzed using Agisoft Photoscan (Metashape Professional (64 bit)) software. The sorts of fractures, patch areas, and rut depths on pavement surfaces may be accurately identified and measured thanks to this technique. When compared to field exams, the findings demonstrated an outstanding accuracy with errors of around 3.54 mm in the rut depth, 4.44 cm² for patch and pothole areas, and a 96% accuracy rate in identifying cracked locations and crack varieties. This study demonstrates how adding GCPs may enhance the UAV image accuracy, particularly in challenging weather and traffic conditions, and promote sustainable pavement management strategies by lowering carbon emissions and resource consumption. Full article

Latent stripping has become increasingly apparent in asphalt pavements, particularly in highway rehabilitation and international construction projects supported by Official Development Assistance (ODA) from the Government of Japan. Stripping accelerates structural deterioration, making countermeasures essential. However, in ODA projects, securing high-quality aggregates or evaluating local materials is often difficult due to environmental and budgetary constraints. This study focused on Surface Free Energy (SFE) as a small-sample evaluation method and developed ten types of styrene–butadiene–styrene (SBS) polymers to enhance interfacial adhesion by targeting aggregate surface functional groups. The SFE of each Polymer-Modified Bitumen (PMB) and thirteen aggregates was measured, and the work of adhesion and moisture sensitivity index (MSI) were calculated for all combinations. Twenty-one Hot-Mix Asphalts (HMA) were then prepared and evaluated using the Hamburg Wheel Tracking Test (HWTT) based on load cycles to stripping initiation (LC_SN) and to 12.5 mm rut depth (LC_ST). The developed PMBs showed a higher work of adhesion, a lower MSI, and substantially increased LC_SN and LC_ST values. Strong negative correlations were observed between MSI and both HWTT indicators, confirming the utility of SFE-based MSI for material screening. This study demonstrates that interface-targeted PMBs can improve stripping resistance, thereby promoting the use of lower-quality aggregates in durable pavements. Full article

The development of sustainable and energy-efficient asphalt pavements is essential to address the growing demand for climate-neutral transportation infrastructure. This study investigates the structural design and functional performance of low rolling resistance asphalt mixtures utilizing reclaimed asphalt pavement (RAP) and warm mix asphalt (WMA) technologies. Ten mixtures with WMA additive—including asphalt concrete (AC) and stone mastic asphalt (SMA) with and without RAP—were evaluated for volumetric and mechanical performance. Laboratory results show that RAP addition did not compromise compaction nor indirect tensile strength ratio (ITSR), and in some cases improved these properties. SMA and SMA RAP-modified mixtures achieved the highest resistance to rutting (as low as 5.0% rut depth), while AC and SMA mixtures both demonstrated low rolling resistance (coefficients of energy loss 0.00604–0.00636). Resistance to low-temperature cracking was strong for all mixtures, with thermal stress restrained specimen test (TSRST) fracture temperatures ranging from −32.8 °C to −36.0 °C. SMA mixtures generally exhibited superior resistance to fatigue (up to 63 με at 1 million cycles). Overall, three asphalt mixtures with different particle size distribution containing 14% RAP and a WMA additive (SMA 8 S_1 R, SMA 8 S_3 R, and AC 11 VS_2 R) demonstrated the best balance of rolling resistance, durability, and circularity, and are recommended for field trials to support climate-neutral and sustainable road infrastructure. These results encourage broader adoption of circular practices in road infrastructure projects, contributing to lower emissions and life-cycle costs. Full article

Increasing the frequency and duration of extreme heat events significantly compromises asphalt pavement performance, particularly in critical urban infrastructure such as heavily trafficked pavements, BRT lanes, and intersections subjected to slow-moving heavy traffic under extreme temperatures. This study systematically investigates rutting formation mechanisms through integrated theoretical and numerical approaches, addressing significant knowledge gaps regarding rutting evolution under coupled extreme-temperature (70 °C), heavy-load (100 kN–225 kN), and braking conditions (1 m/s²–7 m/s²). A three-dimensional thermo-mechanical finite element model integrating solar radiation heat transfer with the Bailey–Norton creep law was developed to quantify synergistic effects of axle loads, travel speeds, and braking accelerations. Results demonstrate that when the pavement surface temperature rises from 34 °C to 70 °C, the rutting depth is increased by 4.83 times. When the axle load is increased from 100 kN to 225 kN, the rutting of conventional asphalt pavements under 70 °C is increased by 56.4%. Rutting is exacerbated by braking acceleration; due to prolonged loading duration under low acceleration, the rutting depth is increased by 30–40% compared with that under emergency braking. These findings establish theoretical foundations for optimizing pavement design and material selection in slow-moving heavy-load environments, delivering significant engineering value for transportation infrastructure. Full article

To address the issue of cracking damage under extreme high-temperature rutting, which is not sufficiently considered in the selection of preventive maintenance programs, the objective of this study was to investigate the preventive maintenance-oriented minor internal damage changes in asphalt concrete with a normal maximum aggregate size of 16 mm (AC-16) under extreme high temperature (70 °C) and load (1.4 MPa) conditions. The changes in void structure within the 0–10 mm rutting depth were tracked through the rutting test and Computer Tomography (CT) image analysis. It was observed that there were notable discrepancies in the three-dimensional (3D) space distribution of void, void volume development, and void morphology between the rut impact zones and the rutted part. The impact zone exhibited a greater prevalence of voids and an earlier onset of cracking. At a rutting depth of only 5 mm, multiple top-down developed cracks (TDCs) of over 6 mm length were observed in the impact zone. At a rutting depth of 10 mm, the TDCs in the impact zone were more numerous, larger, and wider, indicating the necessity for a tailored repair program that includes milling. TDC damage caused by high-temperature rutting is predominantly observed in the upper and middle positions of the height direction, with the bottom position data exhibiting greater inconsistency due to the influence of molding. Furthermore, the combination of void morphology indicators with void volume can effectively track the occurrence and development of microcracks. However, the fine-scale assessment of compaction degree and deformation process using the equivalent void diameter indicator is not sufficiently differentiated. Full article