Fatigue cracking is a major distress in asphalt concrete, with aging identified as a key factor. This study investigated the effects of aging on bitumen–aggregate combinations by evaluating surface free energy (SFE) components of bitumen and aggregates, and calculating adhesion and cohesion energies. Also, the direct Pull-Off tensile test (in cohesive and adhesive failure modes) and indirect tensile fatigue (ITF) test were performed to assess the influence of aging and additives. To mitigate aging effects, ceramic fibers (CF) and granular hydroxy functionalized ultra-high-molecular-weight Polyethylene (FUHMWPE) were incorporated at 1.5% and 3% dosages. Results from SFE analysis were compared with Pull-Off and ITF outcomes to establish a clear relationship between adhesion/cohesion properties and fatigue life of mixtures. The SFE results indicated that aged bitumens, due to their lower non-polar component, form weaker non-polar (covalent) bonds with aggregates, which reduces the bitumen–aggregate adhesion free energy. Consistent with these findings, the pull-off test also showed that the mechanical adhesive strength of aged bitumens with aggregates is lower. The weakened bitumen–aggregate adhesion under aging conditions allowed micro-cracks caused by fatigue in the asphalt concretes to propagate along the bitumen–aggregate interface, thereby reducing the mixture's fatigue life. Furthermore, a decrease in ambient temperature within the intermediate service temperature range of pavements, combined with aging conditions, exacerbates the loss of mixture resistance against fatigue cracks occurring at the bitumen–aggregate interface. In contrast, CF significantly increased the cohesive and adhesive strength of the bitumen–aggregate system under aging conditions, improving the fatigue life of the asphalt concretes by an average of 22%. Similarly, the significant effect of FUHMWPE on enhancing bitumen–aggregate adhesion and cohesion led to an average 27% improvement in fatigue life. This indicates that FUHMWPE has a greater effect than CF on improving the intermediate-temperature properties of the asphalt concrete, owing to the polar functional groups in its polymer structure, possesses higher SFE. This promotes stronger polar interactions with aggregates, resulting in increased adhesive interfacial energy at the bitumen–aggregate boundary and, consequently, greater resistance to fatigue cracks. Statistical analysis results also confirm that both additives at a dosage of 1.5% significantly improve adhesion/cohesion-related properties and fatigue performance. • Aging reduced adhesion energy, increasing fatigue cracks at the bitumen–aggregate. • CF and FUHMWPE improved SFE and reduced cohesion failure in aged asphalt mixtures. • Modified binders showed enhanced interface bonding, improving fatigue resistance. • Pull-Off and SFE results showed strong agreement in assessing cracking mechanisms. • Limestone showed better adhesion than granite, reducing fatigue cracking potential.

Hyperspectral remote sensing for characterizing asphalt binders, mastics, and mixtures under aging conditions

The incorporation of recycled plastics into asphalt mixtures has gained increasing interest as a means to enhance pavement performance while reducing environmental burdens associated with plastic waste. This study examines the use of recycled High-Density Polyethylene (HDPE) and Polyethylene Terephthalate (PET) in asphalt concrete (AC) mixtures produced following the Superpave volumetric mix design. A Hybrid Dry Mixing (HDM) procedure was applied to improve dispersion and prevent clumping, in which aggregates were pre-coated with asphalt binder before introducing finely ground HDPE and PET at dosages of 0.5%, 1.0%, and 1.5% by weight of aggregates. A multi-scale experimental program was conducted to evaluate the thermal, chemical, rheological, volumetric, and compactability responses of plastic-modified mixtures. The thermal and degradation behavior of HDPE and PET were characterized using Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA), while chemical features were assessed through Fourier Transform Infrared Spectroscopy (FTIR). Short-term-aged binders were extracted and recovered using a closed-system asphalt analyzer and rotary evaporator, enabling evaluation of rheological properties through Dynamic Shear Rheometer (DSR) and rotational viscosity (RV) testing. Superpave volumetric properties were determined across multiple asphalt contents, and compactability was quantified using gyratory compaction parameters, specifically the Compaction Energy Index (CEI) and densification slope (K id ). Results show that HDPE softens at mixing temperatures and partially interacts with the binder phase, influencing binder availability, mixture stiffness, and compaction resistance. PET remains solid during mixing and acts as a rigid particulate component, affecting internal structure, void distribution, and densification behavior. These mechanisms explain the observed variations in binder demand, volumetric compliance, and compaction trends across all dosages. The HDM procedure produced uniform mixtures without clumping and is compatible with typical plant operations, supporting its practical relevance for integrating recycled plastics into asphalt pavement construction. • HDM achieved uniform dispersion of HDPE and PET without clumping. • HDPE softened in the mix, while PET acted mostly as a filler. • HDPE stiffened with binder; PET Softened the binder. • Both plastics lowered Gmm and increased the required asphalt content. • All plastic mixtures met Superpave volumetric limits.

To alleviate reliance on unsustainable Trinidad Lake Asphalt (TLA), a novel epoxy-modified MA binder was developed as a substitute for conventional binders. This study evaluated the impacts of curing temperature and duration on the multi-scale microstructural evolution and physicochemical properties of the binder and mixture. FTIR, LSCM, viscometry, and mechanical testing were deployed. Results demonstrate an exponential increase in curing degree over time. Both binder viscosity and phase morphology stabilized after 120 min, achieving a highly uniform polymer dispersion (average particle size: 0.2–0.3 µm) and lowered temperature susceptibility. At the mixture level, elevated curing temperatures enhanced the stiffness modulus and fatigue life but compromised permanent deformation resistance. This performance difference stems from temperature-induced epoxy particle refinement, which alters internal lubrication and healing mechanisms. The developed binder offers a sustainable, high-performance alternative to conventional TLA-MA systems.

The filler-to-binder ratio plays a critical role in determining the rheological performance and fatigue behavior of emulsified asphalt mastics; however, its influence on viscoelastic response and failure characteristics remains insufficiently understood. In this study, emulsified asphalt mastics with different filler-to-binder ratios were prepared using conventional emulsified asphalt and SBS-modified emulsified asphalt. Their rheological and mechanical behaviors were evaluated using dynamic shear rheometer (DSR), multiple stress creep recovery (MSCR), linear amplitude sweep (LAS), and bending beam rheometer (BBR) tests. The results showed that increasing the filler-to-binder ratio enhanced the stiffness and high-temperature deformation resistance of emulsified asphalt mastics, as reflected by increases in complex modulus, rutting factor, and yield stress. However, excessive filler content reduced fatigue tolerance and low-temperature flexibility, as indicated by decreases in yield strain, failure strain, and m-value, together with an increase in low-temperature creep stiffness. The MSCR results further showed that higher filler contents changed the nonrecoverable creep response of the mastics, and negative Jnr-diff values at high filler-to-binder ratios suggested a transition in the rheological response of the highly filled mastic system. For SBS-modified emulsified asphalt mastics, a distinct phase angle inflection point was observed during fatigue loading, which may serve as a rheological indicator for characterizing the transition of fatigue damage behavior. These findings clarify the effect of filler-to-binder ratio on the rheological evolution, deformation resistance, fatigue behavior, and low-temperature performance of emulsified asphalt mastics. The results provide practical guidance for optimizing filler-to-binder ratio design in pavement engineering applications.

Low‑temperature cracking is one of the main causes of asphalt pavement damage in cold regions. While many parameters influencing its low-temperature performance are well-studied, the specific effect of the cooling rate during freeze-thaw cycles (FTCs) on the fracture performance of asphalt mixtures remains largely unexplored. In this study, the effect of cooling rate on the fracture toughness (FT), fracture energy (FE), and cracking‑resistance index (CRI) of asphalt concrete is investigated. For this purpose, dry and saturated semi-circular bend (SCB) samples were subjected to seven FTCs at different cooling rates (0.1, 0.2, 0.5 °C/min, and the shock‑freeze state) and temperatures (− 5 °C, − 15 °C, and − 20 °C), after which they were fractured under a fixed mixed‑mode I/II loading conditions. The results of this study show that increasing the cooling rate reduces all three parameters: FE, FT, and CRI. For instance, applying FTCs with a cooling rate of 0.1 °C/min was significantly less damaging, resulting in a 16% and 20% reduction in FT and FE, respectively, compared to 23% and 48% for the shock‑freeze state. Furthermore, increasing the cooling rate reduces both the displacement and the peak load at the time of fracture. This degradation is attributed to insufficient time for viscoelastic stress relaxation at rapid cooling rates, which promotes a brittle response characterized by higher stiffness and a greater tendency toward elastic behavior. Other factors also contribute to the reduction in mechanical performance, such as the increased thermal gradient between the core and surface, rapid freezing of surface water compared to core water, and volumetric expansion of trapped water within the core. These phenomena collectively increase thermal stresses and accelerate the formation of microcracks. Finally, the influence of temperature in FTCs was characterized: decreasing the temperature reduced the displacement at failure, whereas the peak load first increased down to − 15 °C before decreasing at lower temperatures.

The study investigates the use of Warm Mix Asphalt (WMA) additives as compaction aids for construction of flexible pavements in cold regions. PG 76–28 and PG 58–28 asphalt binders were blended with Rediset, Evotherm, Zycotherm, and Sasobit Redux. Performance Grade, Critical Temperature Differential, Asphalt Binder Cracking Device, Linear Amplitude Sweep, and Fourier Transform Infrared Spectroscopy tests were performed. Results showed that PG 76–28 modified with WMA additives lowered the high PG by 6 °C, while PG 58–28 did not change the PG. ΔTc enhancement resulted solely from modifying PG 76–28 with WMA additives. WMA additives did not affect the low cracking temperature properties of the control binders and reduced the aging susceptibility of asphalt binders. All mixtures were compacted at 149 °C, 127 °C, 104 °C, and 82 °C and evaluated for their cracking, rutting, and moisture-induced damage, yielding different volumetric and performance properties.

While the role of aggregate angularity in the asphalt concrete is well understood, the same is not established for paving concrete mixes. This study evaluates the mechanical, structural and environmental trade-offs associated with aggregate angularity in rigid pavements. Aggregates with angularities (round, sub-angular and angular) maintaining similar sphericity and surface texture were used in two paving concrete mixes (water-to-binder ratios of 0.36 and 0.45). Mechanical properties, porosity and resulting pavement slab thicknesses were assessed for traffic levels ranging from 1,000 to 10,000 commercial vehicles/day and linked to embodied energy and emissions through a cradle-to-gate life-cycle assessment. Higher angularity improved flexural strength and modulus, enabling slab thickness reduction of approximately 15 to 20 mm. Although additional crushing increased emissions, reduced concrete volume resulted in net energy and CO2 reductions of 3-11% per km. A scenario incorporating crusher fines further improved material efficiency, reduced environmental impacts and decreased sensitivity to transportation distance.

Valorization of red mud as an alternative filler for asphalt mastic: modification treatment, pavement performance and environmental impact.

Amplification of seismic stress-induced radon fluxes near surface seals: Application to earthquake precursor detection.

Hydrophobic asphalt emulsion to reduce adhesion between ice and asphalt pavement surface: Development and evaluation for its application over asphalt roads in Subzero temperature regions

Abstract This research investigates the thermal and mechanical self-healing properties of RP plastic-modified asphalt mixtures with [0%, 3%, 5%, 8% and 11%] contents of RP in a baked mixture. RP was mixed with natural asphalt macadam to determine the impact of RP on healing efficiency through dual heating method. The healing performance was assessed using the Healing Index (HI) calculated from the recovery of Indirect Tensile Strength (ITS), which was induced by artificial microcrack damage through cyclic loading (1200 and 600 cycles). Specimens received microwave heating (62°C for 150 s) and external heating (120 s), subsequent to their thermal response comparisons. Microwave analysis results indicated that microwave treatment raised the control mixture temperature to reach 68°C but excess RP content gradually lowered the maximum achieved healing temperature, which only attained 53°C with 11% of RP. The low permittivity of plastic aggregates that insulates heat absorption causes such behavior. They showed only slightly higher external heating healing (HI: 110–118%) than microwave heating (HI: 106–112%). RP content and heating technique were both found to significantly affect healing performance (p < 0.05), with the heating strategy being the most influential. Overall, the thermal and mechanical recovery characterization reveals an optimal RP loading of 3% to 7% in enhancing self-healing performance. It may be more effective to optimize the external heating method for plastic-modified asphalt mixtures, but also excessive RP usage will reduce thermal efficiency. The addition of moderate amounts of recycled plastic enhances the sustainability characteristics and resistance potential to microcracking in asphalt pavement systems.

This study investigates the effects of polyester fiber length and binder type (70-penetration, SBS-modified, and epoxy-modified asphalt) on the fracture behavior of asphalt concrete. Semicircular bending (SCB) tests integrated with acoustic emission (AE) monitoring, Weibull fitting, and K-means clustering were used to evaluate cracking mechanisms. Results indicated that 6 mm fibers optimized AC-13 mixture performance. In SBS-modified mixtures, fibers enhanced toughness, increasing the post-peak fracture energy ratio from 48.52% to 58.34%. Conversely, in epoxy-modified mixtures, fibers improved pre-peak crack resistance, raising pre-peak fracture energy and tensile strength by 64.59% and 20.26%, respectively. Weibull and cluster analyses confirmed that fiber bridging and pull-out delayed crack propagation by promoting cohesive failure. The proposed SCB–AE framework provides quantitative guidance for optimizing fiber parameters to enhance pavement durability.

Increased and excessive axle loads (exceeding design specifications) at high temperatures stimulate premature distresses in flexible pavements. This study utilizes the novelty of engineered bituminous composite—crumb rubber-modified (CRM) stone mastic asphalt (SMA) for pavement longevity and sustainable performance. Dynamic modulus testing was employed at four temperatures and six frequency sweeps. The experimental design included the preparation of SMA 19 specimens with six different percentages of crumb rubber (CR) mixed in bitumen. CR addition to the mix translated into an improved stiffness of the mix, as a 64% increase in dynamic modulus (on average) was reported at 10% CR as compared to a neat mixture. Master curves were produced using |E*| test results, which revealed that 10% modified SMA was relatively stiffer and more rut-resistant than the other mixtures. Performance prediction models were developed for |E*| using artificial neural networks (ANNs) and non-linear regression, wherein the former proved to be more robust. Sensitivity analysis revealed that a temperature rise (21.1 to 37.8 °C) translated into a 65% drop in |E*| (on average) and a rise in frequency (0.1 to 25 Hz) divulged a 72% upsurge in |E*| (on average). This research demonstrates the promise of deploying CR SMA mixtures, particularly for high-traffic and heavy-load scenarios.

HighlightsDevelop a novel organic viscosity-reducing warm mix asphalt additive (PNSK).Determine the optimal PNSK dosage at 11% by balancing different properties.Demonstrate superior fatigue resistance and lower strain sensitivity of PWMA through LAS.Characterize the stress-temperature sensitivity and deformation behavior using MSCR.A composite warm-mix additive (PNSK) was developed to improve asphalt workability by reducing viscosity while maintaining rheological performance at both high and low temperatures. The warm-mix asphalt binders (PWMA) were analyzed using an integrated approach combining conventional property tests with rheological analysis. Results showed that penetration, softening point, and ductility improved. The viscosity-reduction effect was enhanced with increasing PNSK dosage, yet the benefit plateaued beyond 11% content. Additionally, the adhesion strength between asphalt and aggregate began to decrease after 11% dosage, with 12% serving as the critical threshold for adhesion deterioration. Consequently, the optimal dosage was determined to be 11% based on comprehensive consideration of all factors. LAS results demonstrated that 11%PWMA exhibited lower strain sensitivity and superior fatigue resistance at low-to-intermediate temperatures, with fatigue life increasing by nearly an order of magnitude under low strain at 20 °C. MSCR results revealed that under low stress, 11%PWMA exhibited significantly lower non-recoverable creep compliance (Jnr) and higher percent recovery (R) than the 70#, especially in the high-temperature range (54–66 °C), demonstrating superior resistance to permanent deformation. However, 11%PWMA exhibited temperature-strain sensitivity characteristics under high-temperature, high-strain conditions, representing an inherent characteristic of WMA technology.

Stone mastic asphalt (SMA) exhibits high rutting resistance and durability; however, it is prone to binder draindown due to its high asphalt content. This study aims to evaluate the effect of mixing production procedures on the draindown of SMA using steel slag and coconut fiber. The research was conducted in two steps: first, different coconut fiber addition methods for SMA with stone aggregates were evaluated, and an appropriate procedure was selected based on draindown test results; subsequently, the production procedure for SMA using steel slag was adjusted and evaluated in comparison with the conventional SMA production procedure using crushed stone aggregates and cellulose fiber in accordance with TCCS 36:2021/TCĐBVN. The study results indicate that increasing the aggregate heating temperature by approximately 10 °C, extending the mixing time by an additional 30 seconds, and introducing coconut fiber using the dry-mixing method together with mineral filler during asphalt binder addition help to mitigate asphalt drain-down and improve Marshall stability as well as the volumetric properties of SMA. The findings contribute to the proposal of a suitable production procedure for SMA using steel slag and coconut fiber under practical production and construction conditions.

Intermediate-temperature cracking is a major phenomenon in asphalt pavements that adversely affects long-term performance and durability. Therefore, several modification techniques have been employed to improve the toughness and mechanical performance, e.g., with polymers and nano fillers. This study investigated the influence of a graphene oxide-styrene butadiene nanocomposite (GOSBN) on the Intermediate-temperature cracking behavior of asphalt mixtures. It also assessed the efficacy of GOSBN on improving fracture energy, fracture toughness, and adhesion-cohesion properties at various temperatures. To study the mixture's temperature-related responses, semi-circular bending (SCB) and pull-off tests were conducted at three temperatures (5, 15, and 25°C). To performance-grade bitumens (PG 64 - 16 and PG 58 - 22) were selected to study the compatibility with different mixture formulations, while two aggregate sources (granite and limestone) were used to investigate the effects of mineralogy. GOSBN was added to bitumen at concentrations of 0%, 0.4%, and 0.8% by bitumen weight to evaluate its effect on the properties of asphalt mixtures. PG 64 - 16 exhibited superior intermediate-temperature performance compared to PG 58 - 22, particularly in fracture energy, fracture toughness, and adhesion, suggesting that a stiffer binder enhances resistance to intermediate-temperature cracking. Additionally, increasing GOSBN dosage significantly improved fracture energy, fracture toughness, and crack propagation resistance across all temperatures, reinforcing the effectiveness of nanocomposite modification. Limestone-based mixtures demonstrated better adhesion performance than granite-based ones, confirming the chemical compatibility between limestone's alkaline nature and bitumen's acidic properties. GOSBN increased the bitumen's cohesion pull-off strength and the bitumen-aggregate adhesion pull-off strength. These findings emphasize the importance of bitumen selection, aggregate mineralogy, and modifying incorporation in optimizing asphalt mixture performance and prolonging pavement lifespan.

Consideration of losses and legal issues related to negative radiation rumours in Korea.

Macrotexture is critical for pavement skid resistance in wet conditions, yet conventional mixtures face a trade-off between durability and texture depth. This study proposes Fluid Mastic Asphalt (FMA), a skeleton-superdense mixture in which flowable asphalt mastic fills the aggregate skeleton. By adjusting the filling degree, macrotexture can be controlled while maintaining high durability. FMA mixtures with varying filling degrees and asphalt–aggregate ratios were evaluated through abrasion and rutting tests. Results recommend an optimal filling degree of 94%–96%. Compared with AC and SMA, FMA exhibits superior skid durability, with BPN degradation rates reduced by 34.5% and 19.5%, respectively. For MTD, FMA retains values above 1.4 mm after abrasion, reaching 4 and 1.65 times those of AC and SMA. An XGBoost model was developed to analyze FMA skid resistance degradation, with SHAP values quantifying the contributions of input factors.

With regard to the antiseepage structure of rockfill dams, the force and deformation safety of an asphalt concrete core are of great concern. At present, the main methods for studying the force and deformation of the asphalt concrete core are numerical simulation methods, model test methods, and on-site monitoring methods. However, the simulation process of numerical simulation methods is relatively complex. It is difficult to select the appropriate material scale for model test methods, while on-site monitoring methods are found wanting on the issue of design and construction. Therefore, an analytical prediction model (APM) that offers important theoretical values and engineering application prospects to quickly and easily investigate the force and deformation of the asphalt concrete core is explored in this study. The deformation functions of the rectangular thin plate with three edges clamped and one edge free (CCCF rectangular thin plate) on the Winkler elastic foundation under the coaction of horizontal loads (hydrostatic pressure and active earth pressure) and vertical load (gravity) are solved via the small deflection bending theory of thin plates, the plane stress theory of thin plates, and the Rayleigh–Ritz method. Then, the stress functions of the CCCF rectangular thin plate are derived via the geometric and physical equations of the thin plate. The one-to-one mapping relationship between the CCCF rectangular thin plate and the asphalt concrete core is established. Furthermore, the deformation and stress of the CCCF rectangular thin plate are transformed into the trapezoid asphalt concrete core, the polyline asphalt concrete core, and the arbitrary asphalt concrete core via the one-to-one mapping relationship. The analytical force and deformation analysis model of the asphalt concrete core is established. Finally, the reliability of the APM is verified by the FEM. The APM is applied to analyze the force and deformation characteristics of the asphalt concrete core with 150 m height. The results show that the deformation laws of the two methods are basically consistent. The maximum difference values of settlement, axial deformation, and flexural deformation for the two methods are 3.1%, 0.8%, and 18.8%, respectively. The APM is found to be reliable. For asphalt concrete core rockfill dams with heights of 150 m or higher, the asphalt concrete core experiences large tensile stress and the risk of tensile failure. Therefore, improvement measures should be taken to reduce the tensile stress of the asphalt concrete core. The APM can be more convenient and easier to estimate the force and deformation of the asphalt concrete core than the FEM. The APM has expanded the calculation methods for the force and deformation of the asphalt concrete core.