Stomata and pavement cells are fundamental components of the leaf epidermis, jointly regulating gas exchange, water loss, and leaf surface expansion. Stomata size, aperture, density, and pavement cell morphology are critical parameters for assessing plant transpiration efficiency, epidermal growth dynamics, and adaptive responses to environmental constraints. Despite their biological importance, quantifying stomatal and pavement-cell traits remains seldom not generalized, simple, and fast enough . Manual or semi-automated approaches limit large-scale phenotyping and restrict the integration of epidermal morphology into crop-improvement pipelines aimed at developing climate-resilient varieties with optimised stomatal patterning. To address such limitations, we developed Stomatalia, a deep learning-based platform designed to automate and standardise the quantification of stomatal and pavement cell traits. The algorithm was trained on epidermal images of cultivated and wild potato and tomato genotypes grown under optimal and abiotic-stress conditions. Stomatalia automatically detects stomata and pavement cells and extracts a broad range of morphological and integrative epidermal parameters, enabling high-throughput phenotyping within a unified workflow. Prior to platform development, we optimised a rapid, minimally-destructive leaf-printing protocol that generates negative impressions of the leaf surface within 40-100 s. Transparent positive prints were subsequently produced and imaged under a light microscope at scale settings ranging from 20 to 200 μm. The resulting images are analysed using Stomatalia's user-friendly web-based interface, which runs an instance-segmentation deep learning algorithm to detect, count, and calculate stomatal and pavement cell parameters. The platform outputs structured files containing raw measurements, derived integrative traits, and associated metadata, facilitating downstream statistical and physiological analyses. Algorithm evaluation on independent datasets demonstrated high performance within the validated dicot imaging domain, with F1-scores ranging from 0.86 to 0.94 depending on image scale, species, and resolution, and high segmentation overlap for both stomata and pavement cells. The generality of stomatal detection was also tested on spring onion, chickpea, balsam poplar, and wheat in cross-species feasibility tests, although performance was more variable in monocots, and pavement-cell segmentation remained species- and architecture-dependent. Benchmarking against another publicly available app further showed that, under the tested web interface settings and image types, Stomatalia exhibited closer agreement with manual counts and substantially faster processing times. The practical performance of Stomatalia was further tested in a proof-of-concept trial with potato plants subjected to optimal irrigation and a long, gradual drought. The platform reliably quantified epidermal traits despite variations in leaf morphology and image quality, supporting the integrated interpretation of stomatal and pavement-cell responses under stress. We developed Stomatalia as a robust, user-friendly deep learning platform for automated, high-throughput analysis of bright-field leaf epidermal images across varying magnifications and resolutions. Stomatalia facilitates rapid, reproducible, and coordinated phenotyping of stomatal and pavement cells by integrating methodological standardisation, computational automation, and multi-trait extraction in a single analytical workflow. Its strongest current application is the analysis of high-quality dicot leaf-print images, particularly in species and imaging conditions similar to those used for model training and validation. Cross-species and benchmark analyses further define its current scope: stomatal detection can be transferred to some additional epidermal architectures, whereas robust pavement-cell segmentation in monocots or highly divergent species will require further annotation and model retraining. Within these defined boundaries, Stomatalia provides a flexible and extensible framework for studying stomatal and pavement cell morphology and environmental plasticity, while also supporting broader efforts to dissect and optimise plant responses to abiotic stress.
Expansive soils pose significant challenges to construction of pavements because of their swelling behaviour, low strength and high moisture sensitivity. This paper examines the use of cement kiln dust (CKD) and polypropylene fiber (PPF) as chemical and mechanical stabilizers respectively to enhance expansive subgrade soil and assesses the implication of this on the thickness of flexible pavement based on the IRC guidelines. Laboratory tests were conducted in a sequence in order to evaluate swelling, plasticity, strength and bearing properties, and the pavement design was made according to mechanistic-empirical IRC processes. The findings revealed that CKD has a great influence on the behavior of soil in terms of cation exchange and pozzolanic reactions, in which the behavior of clay becomes less active and subsequently increases its stiffness and the load-bearing capacity. The polypropylene fibers added further mechanical restraint by fixing microcracks and reducing the volumetric deformation and thus increasing ductility and post-peak performance. The integrated stabilization system altered the soil to low-plasticity and dimensionally stable subgrade that can support pavements in compliance with IRC standards. The optimal combination of 20% CKD and 1.5% PPF significantly improved the performance of expansive soil, reducing DFS from 75.38 to 9.48% and PI from 32.2 to 4.5%, while improving UCS from 280 to 1340 kPa after 90 days curing and soaked CBR from 3.47 to 15.3%. The resulting changes led to the reduction of pavement thickness from 595 to 530 mm, which represents a savings of about 10.92% in material. The inclusion of the stabilized subgrade properties into IRC pavement design reported a significant decrease in total pavement thickness across all traffic classes, up to a maximum of approximately 10.9% in 20 msa traffic. The research also provides a direct correlation between sustainable soil stabilization and structural pavement response, and indicates the possibility of CKD-PPF systems to be cost effective and environmentally friendly systems of pavements construction. The microstructural analysis established that cementation (C-S-H/C-A-H formation) of the clay matrix due to CKD and polypropylene fibers contributed the crack-bridging restraint, which, together with the cementation of the clay matrix, contributed to strength enhancement, volumetric stability, and decreased pavement thickness.
Current methods for detecting and evaluating pavement skid resistance vary widely, yet each has its own scope of applicability and inherent limitations. Therefore, this paper proposes a method based on U-Net model segmentation to obtain binary images of asphalt pavement surfaces, enabling precise calculation of pavement texture distribution parameters. A dataset required for model training and testing was constructed, and preprocessing was performed on forward-collected asphalt pavement images to eliminate noise interference. Based on the established three-dimensional asphalt pavement model, reverse engineering is employed to obtain binary images of the pavement surface as target images for model training. A U-Net semantic segmentation model is constructed to train the segmentation of asphalt pavement images, distinguishing between the aggregate and void components of the pavement. The feature parameters of the binary images generated by U-Net segmentation are calculated and correlated with the average texture depth measured using the sand patch method. Results indicate that the U-Net model achieved an F1-score of 0.7214 on the validation set, demonstrating satisfactory segmentation performance for subsequent texture parameter extraction. The correlation coefficient R² between the mean texture depth (MTD) calculated from the binary image and the sand patch method reached 0.85, while the correlation coefficient between the fractal dimension and MTD-1 was 0.86. Both correlations were statistically significant at the 95% confidence level. The proposed method can provide effective technical support for texture-based skid resistance evaluation of asphalt pavements.
Leaf pavement cells of many plant species develop jigsaw puzzle-like shapes in which neighboring cells interdigitate, providing an ideal model for the study of cell shape regulation. Such shapes are likely to reduce tissue-wide mechanical stress, which is influenced by environmental conditions, such as drought stress. We analyzed pavement cell shape complexity in a natural population of European aspen (Populus tremula) genotypes and used a genome-wide association study (GWAS) to identify a candidate gene in cell shape regulation, Potra2n8c18226, encoding the transcription factor MYB305a. We subsequently validated a role for MYB305a in regulating aspen leaf pavement cell shape. We then demonstrated that drought stress strongly induces MYB305a promoter expression in these cells and provided evidence that MYB305a plays a role in regulating pavement cell shape in response to drought. Finally, we observed correlations of pavement cell shape complexity with water-use efficiency and average precipitation at the original sampling sites, in the natural aspen population. Taken together, our results suggest climatic variables affect shape complexity of pavement cells in aspen leaf and provide a foundation for future mechanistic studies on this process, by implicating the involvement of the transcription factor MY305a.
Cell shape acquisition is a fundamental biological process that allows cells to establish and maintain morphologies adapted to their specialised functions while preserving tissue integrity. In plants, this process is strongly influenced by the presence of the cell wall, a dynamic extracellular network of polysaccharides and proteins that surrounds the plasma membrane and physically connects neighbouring cells. By constraining and directing cellular expansion, the cell wall plays a central role in controlling cell shape. In Arabidopsis leaves, epidermal pavement cells adopt a characteristic jigsaw-puzzle-like morphology through the formation of interdigitating lobes and necks, providing a powerful model system for dissecting the mechanisms underlying complex plant cell shape acquisition. Here, we demonstrate the involvement of the glycoside hydrolase BETA-GALACTOSIDASE 10 (BGAL10) in pavement cell morphogenesis. Using high-resolution time-series imaging, we analysed cell growth dynamics alongside the spatial expression and subcellular localisation of BGAL10, revealing a prominent role for BGAL10 in mature cells, particularly at curved regions of the cell wall along pavement cell lobes. Furthermore, Brillouin microscopy revealed altered mechanical properties in the bgal10-1 mutant, most notably at lobe-indentation interfaces and cell junctions. Together, our results indicate that BGAL10 fine-tunes lobe outgrowth, likely through modification of the hemicellulose matrix, thereby regulating cell wall extensibility and mechanical stress distribution during pavement cell shape acquisition.
Early-age shrinkage cracking in concrete bridge deck pavements is a pervasive infrastructure challenge, with approximately 42% of decks developing cracks within the first week after construction. These defects raise long-term maintenance costs and weaken structural durability. This study assesses hybrid fiber-reinforced concrete, or HFRC, as an alternative to conventional reinforced concrete, using material property tests, two-dimensional digital image correlation (2D-DIC), and restrained shrinkage tests to compare crack resistance. Key findings show HFRC outperforms conventional concrete. Full-field 2D-DIC analysis revealed significant strain concentrations along the steel bars in traditional pavement layers. This suggests that the stiffness mismatch between the high-modulus steel reinforcement and the concrete matrix, coupled with internal restraint effects, may induce localized stress concentrations that guide the development of macro-cracks. Restrained shrinkage tests found traditional pavements formed more than 50% of their cracks within three days, while HFRC reduced total crack area by over 93% after 14 days, bringing it to less than 1/16 of conventional levels with notably smaller crack widths. This research identifies HFRC as a material-efficient alternative with potential durability benefits for effectively mitigating early-age cracking in bridge deck pavements. Its enhanced performance is attributed to the improved compatibility between material-scale deformation demands and system-level boundary restraints, which is interpreted to prevent restraint-induced stress concentrations from reaching the macroscopic cracking threshold.
This study employed a greenhouse gas flux monitoring system equipped with LI-COR 7810/7820 portable trace gas analyzers to measure daily fluxes of CO2, CH4, and N2O across asphalt pavement sections during three time periods (8:00-9:00 AM, 1:00-2:00 PM, 6:00-7:00 PM). Using high-frequency data obtained from the analyzers, precise fluxes were calculated via an exponential fitting model in SoilFluxPro software. A comprehensive assessment, integrating spatiotemporal statistical analysis and global warming potential (GWP), was conducted. The results revealed the following: (i) Spatial distribution: Asphalt road surfaces act as carbon sources along both sides, with an average GWP of 920.762 nmol·m⁻2·s⁻1 per day, while the central section serves as a weak carbon sink, with an average GWP of -73.685 nmol·m⁻2·s⁻1 per day. (ii) Temporal distribution: Greenhouse gas emissions from asphalt pavements are higher during the daytime and lower at night. (iii) Gas composition: CO2 is the dominant contributor to greenhouse gas fluxes from asphalt pavements, accounting for over 98% of total emissions. (iv) Primary drivers: The primary source of greenhouse gas emissions from asphalt pavements is the organic debris covering the soil and vegetation along roadside areas.
Aggregates comprise up to 95% of flexible pavement composition, critically influencing performance based on geological source and processing methods. In Pakistan, where approximately 264,175 km of roads carry 96% of inland freight, premium Margalla aggregates face increasing demand and depleting reserves, necessitating sustainable alternatives. This study comprehensively evaluates aggregates from five key quarries (Margalla, Malakand, Kohat, Swabi, and Besai) for highway suitability. Rigorous laboratory testing encompassed macro-level physical and mechanical properties and micro-characterization using Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), and Fourier Transform Infrared Spectroscopy (FTIR), alongside performance tests including Indirect Tensile Strength (ITS), rutting resistance, and fatigue analysis. Overall, Margalla aggregates exhibited the best performance, showing the lowest abrasion value (21%), highest Tensile Strength ratio (TSR) (82%), highest conditioned ITS (433.7 kPa), highest dynamic modulus (2120 MPa at 25 Hz), and the lowest rut depth (7.8 mm at 10,000 cycles). These superior properties are attributed to their favorable physical characteristics and high calcium content. Malakand and Kohat aggregates also demonstrated satisfactory performance, with TSR values of 79% and 76%, conditioned ITS values of 408.7 and 377.7 kPa, and rut depths of approximately 8.8 and 10.5 mm, respectively, indicating their suitability for medium-traffic pavements. In contrast, Swabi and Besai aggregates exhibited lower moisture resistance (TSR = 77% and 75%), lower conditioned ITS (355.7 and 337.7 kPa), and higher rut depths (~13.0 and 14.2 mm), making them less suitable for high-stress pavement layers. These findings support Malakand and Kohat aggregates as viable regional alternatives to Margalla.
Polyurethane-modified epoxy crack sealants can combine the cohesive strength of epoxy networks with the flexibility required for asphalt pavement crack repair. However, their selection under different winter pavement-temperature conditions requires an integrated evaluation of workability, low-temperature transition, dimensional stability, aging resistance, and interfacial adhesion. In this study, six ambient-curing polyurethane-modified epoxy crack sealants (EUPC) were prepared and assessed under representative winter pavement-temperature conditions, with SBS-modified asphalt used as a reference. All EUPC formulations satisfied the 30 min construction-window requirement, showed Tg values below 0 °C, T5% values above 300 °C, and curing volume shrinkage no higher than 3.0%. After moisture-oxygen-ultraviolet coupled aging, the formulations retained a substantial proportion of both tensile strength and elongation, with EUPC-3/EUPC-4 showing a relatively balanced strength-ductility response. Compared with SBS-modified asphalt, the climate-matched EUPC formulations provided higher direct tensile adhesion, oblique shear adhesion, and flexural-tensile repair recovery. Overall, EUPC-1/EUPC-2, EUPC-3/EUPC-4, and EUPC-5/EUPC-6 are more suitable for mild, cold, and severe low-temperature winter conditions, respectively.
When traditional geogrids are used to mitigate reflective cracks in asphalt pavement, it is difficult to monitor the internal state of the pavement and the strain of the geogrid in real time. This study proposes a sensing geogrid based on warp-knitting technology, where fiber Bragg grating (FBG) sensors are embedded into the geogrid through the weaving process, enabling it to possess both reinforcement and strain-sensing functions. The sensing geogrid was calibrated through laboratory tensile tests, and field monitoring was conducted to obtain optical signal variation data at various stages during asphalt pavement paving, as well as the deformation of the geogrid at different measurement points in each stage. The results indicate that the weaving process did not damage the FBG sensors, and the sensing geogrid exhibited good optical signal performance and normal signal acquisition during the production and transportation stages. The strain of the FBG sensors and the geogrid showed a linear correlation, with a correlation coefficient of 845 με/nm, demonstrating good deformation compatibility between them. Field monitoring confirmed that the sensing geogrid has good construction adaptability and can perceive fluctuations in optical signals and deformation of the geogrid during the construction process. Specifically, significant deformation of the geogrid occurred during the construction of the asphalt-treated base (ATB-25) and bottom layers, accompanied by substantial fluctuations in optical signals due to construction machinery. In contrast, signal fluctuations were smaller during the construction of the middle and surface layers, with the influence depth of construction machinery being approximately 22 cm. Compared to ordinary road sections, the deflection basin curve of the reinforced section was gentler, and the maximum deflection was reduced by approximately 41%. This study confirms the feasibility of the sensing geogrid and provides a valuable reference for its application in road engineering.
To address the issues of poor sustained-release behavior and limited long-term efficacy associated with conventional salt-storage materials, this study developed the epoxy-resin-encapsulated slow-release salt-storage filler to enhance both the engineering performance and the deicing/snow-melting capacity of salt-storage pavements. In this study, attapulgite was optimized and selected as the salt storage carrier through the adoption of pesticide coating technology and experimental testing, wherein a deicing salt blend with a CaCl2 to NaCl mass ratio of 2:1 was loaded via a wet adsorption method. Subsequently, using dimethicone as the surface modifier, the optimal encapsulation process was determined to involve the dilution ratio of epoxy resin to cyclohexanone of 4:1 and the curing agent dosage of 30% by weight. The results indicated that the recommended content of the filler should not exceed 5%. The filler reduced the high-temperature stability and water stability of the mixture, while the low-temperature crack resistance first increased and then decreased, peaking at the 2% filler content with an improvement of 12.2%. The water stability was the most significantly affected by the filler content. Ice-snow melting performance tests demonstrated that the salt-storage mixture with 5% filler achieved the deicing rate of 56.35% at -5 °C, meeting the industry standard requirements. The self-prepared slow-release salt-storage filler exhibited superior long-term ice-snow melting performance to V-260, with the slow-release duration extended by 60%. The salt release process was divided into three distinct stages: rapid dissolution, stable release and slow dissolution. The 60 °C was determined as the optimal temperature for the accelerated immersion testing, which the accelerated test could effectively simulate the natural immersion process. Based on the prediction model established accordingly, the functional service life of snow-melting for this slow-release salt-storage asphalt pavement in northern area was estimated be approximately 4.07 years. The slow-release salt-storage filler fabricated in this work possesses both remarkable sustained-release behavior and deicing efficacy. The findings provide the technical foundation for the development of novel salt-storage pavement materials, performance characterization, and mechanistic analysis of snow-ice melting.
Pavement texture strongly affects skid resistance, drainage, and tire-pavement contact stability, yet its transverse evolution under wheel-track-concentrated loading remains insufficiently quantified. This study proposes a 3D-laser-scanning-based framework for evaluating the transverse homogeneity of preventive maintenance pavements during service. Ten field sections on the Jiangluo Expressway in Guangdong Province, China, covering five preventive maintenance surface systems at two service stages (six months and one year), were investigated. Reflection intensity histogram features and geometric texture parameters were screened against transverse wheel-track distribution to identify representative indicators of asphalt film peeling and aggregate wear. Weighted average grayscale was selected as the optical indicator, whereas height-distribution kurtosis was selected as the geometric indicator. A section-level homogeneity index based on normalized median absolute deviation was then used to quantify transverse dispersion. The results show that weighted average grayscale and kurtosis are the most sensitive of the tested indicators to transverse wheel-track distribution, with R2=0.973 and R=0.9057, respectively. Wheel-track regions generally exhibited more severe optical and geometric deterioration than non-wheel-track regions, and transverse homogeneity tended to decrease from six months to one year. Within the investigated expressway sections, the framework was sensitive to different degrees of service-stage transverse wear evolution; however, broader multi-site validation is still required before threshold-based general applications can be established.
The thermo-mechanical degradation of the base-subgrade interface in airport pavements was investigated using a three-dimensional sequentially coupled finite element framework in ABAQUS 2023, in which progressive interfacial debonding was described by a bilinear cohesive-zone model through the damage variable CSDMG. The results show that thermal loading markedly accelerates interface degradation when combined with moving wheel loads. Compared with the wheel-loading-only condition, thermo-mechanical coupling advances the first damage initiation from 0.04993 h to 0.00254 h and shortens the severe-degradation stage from 1.000 h to 0.00927 h. This acceleration is attributed to a thermal stress pre-weakening effect, whereby constrained thermal deformation partially consumes the available cohesive resistance and shifts the interface closer to the softening threshold before external loading is applied. A decomposition of the mixed-mode initiation criterion further indicates that the first damage event is governed by synergistic normal-shear interaction, with the normalized contribution ratio (tn/tn0)2:(ts/ts0)2 = 0.38:0.62, showing that wheel-induced shear is the dominant trigger while tensile opening induced by thermal curling provides substantial preconditioning assistance. In addition, a representative normalized comparison between simulated average CSDMG and cumulative AE hit count demonstrates a consistent stage evolution from distributed deformation to accelerated localization and residual stabilization. These findings indicate that the base-subgrade interface should be treated as a temperature-sensitive weak layer in airport pavement assessment, particularly near joints and other discontinuity-controlled regions.
The performance of asphalt pavements is significantly reduced due to overloading of vehicles, leading to increased rutting and cracking, and costs of maintenance, especially in developing countries like Pakistan, where the limits of axle loadings are not well enforced. Local conditions, weak subgrades, variable materials and atypical traffic limit the use of conventional designs and point to the need of sophisticated mechanistic prediction tools. This study develops a validated three-dimensional (3D) viscoelastic finite element model (FEM) in Abaqus to assess pavement responses under overloaded traffic. The model features an improved rectangular-semicircular tire contact approximation that more closely represents real contact geometry than conventional circular assumptions, Prony series coefficients from uniaxial stress relaxation tests for time-dependent asphalt behavior, cyclic moving loads derived from axle load frequency distributions obtained through Weigh-in-Motion (WIM) monitoring on Pakistan's National Highway, with peak loads representing the most severe overloading events recorded across all vehicle classes and regionally calibrated layered properties. Validation against benchmarks achieved 95% agreement in stress distributions, deformations, and rut depths. Results show overloading markedly intensifies distress relative to legal loads. For 2-axle trucks, stress rises 157% and rutting depth 125%. The 3-axle configuration is the most damaging with 250% and 190% increase in stress and rutting, respectively. The coalescence of inter-axle stress bulbs results in continuous high-strain corridors, thus accelerating the time-dependent creep deformation in the linear viscoelastic framework. Four-axle configurations give the best redistribution and mitigation, with the benefits diminishing with more than four axles, as additional wheels redistribute, rather than reduce, the strains beyond the material limits, while rut accumulation continues. The results show that axle multiplication has its limits in terms of gross overloading. The model sets a solid foundation for forecasting distress in nascent networks, and suggests rigorous enforcement, targeted high strain maintenance and local data input to mechanistic-empirical designs to enhance resilience and sustainability.
Asphalt pavements in hot and humid regions such as Southeast Asia are highly susceptible to moisture-induced debonding, especially when WMA is produced using marginal aggregates or less favorable gradation conditions. This study develops an anti-stripping-focused polymer-modified WMA system using SBS and a silane-based liquid additive. This study focuses on evaluating the coupled contribution of SBS-related binder cohesion and silane-related interfacial adhesion under poor gradation conditions, and verifies the selected system through binder-level, mixture-level, durability, and cost-efficiency evaluations. SBS contents of 4.0%, 4.5%, and 5.0% by binder mass were combined with silane dosages of 0%, 0.05%, 0.10%, and 0.15%. The mixtures were evaluated using MSCR, Marshall stability and flow, dry and wet ITS, TSR, Hamburg Wheel Tracking, SCB, and Overlay Test. SBS alone increased dry ITS and Marshall stability, but silane-free mixtures still showed low TSR values of 71.7-73.3%. The optimum mixture, S4.5-Si0.10, achieved a dry ITS of 0.94 MPa, wet ITS of 0.80 MPa, TSR of 85.1%, and Marshall stability of 13.8 kN. MSCR results confirmed that SBS reduced accumulated strain at both 0.1 and 3.2 kPa, while silane did not adversely affect binder deformation resistance. In Stage 2, the optimized SBS-silane mixture under poor gradation reduced Hamburg final settlement by 54.7% compared with the poor-gradation control. SCB work of fracture increased from 1.34 J to 5.20 J, and Overlay Test results confirmed improved load retention. The optimized mixture also reduced the annualized cost index by 27.2%. These findings demonstrate that a balanced SBS-silane WMA system can improve debonding resistance and durability under hot and humid pavement conditions.
This study aims to systematically evaluate the balancing mechanism between road performance, carbon emissions, and economic cost when selecting asphalt materials for severe cold regions, filling the gap in multi-criteria decision-making for composite chemical modifications. To address alternating temperatures, heavy traffic, and modified asphalt transport difficulties, this study presents a novel evaluation framework focusing on the performance-environmental-cost nexus of a desulfurized rubber powder composite SBS-modified asphalt mixture, which provides a clear technological breakthrough for high-ratio scrap tire recycling in seasonal frost zones. Two reference mixtures serve as comparisons: a conventional rubber powder composite SBS (styrene-butadiene-styrene triblock)-modified asphalt mixture (CR-SBS) and an SBS-modified asphalt mixture (SBS). A comparative experiment was conducted between the two materials and the SBS-modified asphalt mixture (ACR-SBS) compounded with desulfurized rubber powder. High-temperature stability was tested by the rutting test, low-temperature crack resistance by the beam bending test, and water stability by the immersion Marshall and freeze-thaw splitting tests. Life cycle carbon emissions and economic costs were quantified from raw material acquisition to construction. The results show that desulfurized rubber powder composite with ACR-SBS delivers the most superior overall road performance. However, it also generates the highest life cycle carbon footprint. Its total carbon emission reaches 162,800 kgCO2eq, which is 13.7% (19,600 kgCO2eq) higher than SBS (143,200 kgCO2eq) and 7.7% (11,600 kgCO2eq) higher than CR-SBS (151,200 kgCO2eq). The total cost of ACR-SBS is 391,000 CNY, which is 1.5% (6000 CNY) higher than SBS (385,000 CNY) and 1.3% (5000 CNY) lower than CR-SBS (396,000 CNY). These findings provide a basis for the selection of high-performance, low-carbon, and economical composite-modified asphalt in severe cold regions.
With the rapid development of intelligent connected vehicles and autonomous driving, real-time and accurate road condition perception has become increasingly critical. Aiming at the limitations of traditional direct and indirect detection methods, this paper proposes an ultrasonic-based real-time detection system for road roughness. Most urban roads today feature asphalt pavements; therefore, this system focuses its research on asphalt pavements. Under the same pavement type (asphalt roads), there is a strong correlation between pavement roughness and the friction coefficient. By measuring the roughness of different pavements, the friction coefficient is estimated using the fuzzy processing method. Then the system through measuring ultrasonic echo amplitude and sensor-road distance, combined with software digital filtering, dual-parameter compensation (distance and temperature-humidity), probabilistic statistical analysis, and fuzzy inference, the mapping relationship among echo signals, road roughness and friction coefficient is established. The system mainly includes an ultrasonic transceiver module, a hardware signal conditioning module, and an MCU-based data processing, display and transmission module. Both simulated experiments and real asphalt pavement tests are carried out for verification. The results show that the system can effectively suppress noise, compensate distance attenuation and environmental interference, and achieve accurate real-time detection of road roughness, with a relative error less than 10% compared with the reference value. The proposed system can provide reliable data support for vehicle active safety systems and autonomous driving applications.
It is important to incorporate polymers into bituminous binders to improve the quality and performance of asphalt. Currently, polymer-modified asphalt binders (PMBs) play an important role in road engineering. Polymer modifiers absorb the maltene fractions of bitumen and form a three-dimensional network within the binder. The service life of polymer-modified asphalt pavements is approximately 24% longer than that of conventional pavements. Polymer additives are used to improve the properties of bitumen, such as increasing its strength and resistance to loads and extreme temperatures. Common additives include elastomers such as styrene-butadiene-styrene (SBS) and styrene-butadiene rubber (SBR). Plastomers such as ethylene vinyl acetate (EVA) are also widely used. These additives improve the stiffness and high-temperature performance. These modifications create polymer-modified bitumen, which is used in road surfaces to prevent cracking, rutting, and other types of wear, especially in areas with heavy traffic or extreme climates. Some of the main types of polymer additives include SBS, a common elastomer that improves elasticity and flexibility, making asphalt more resistant to cracking and rutting, especially at high temperatures and under heavy loads, and EVA, a plastomer that gives bitumen stiffness and strength. Styrene-butadiene rubber (SBR) is another elastomer used to modify bitumen and exhibits properties similar to SBS. Crumb rubber is a recycled material obtained from waste tires and can be used as an alternative modifier. Other additives include ethylene-propylene copolymers and various polyalkyl methacrylates, although the latter materials sometimes have limited applicability. The advantages of polymer modification include increased durability (makes the asphalt pavement more resistant to wear), increased thermal stability (improves performance at both high temperatures (rutting) and low temperatures (cracking)), increased elasticity and recovery (improves flexibility, allowing the pavement to better withstand loads), and reduced maintenance requirements (extends the service life of the pavement). This paper provides a review of research studies on the use of polymer additives to improve the rheological properties of bitumen. Although numerous studies have investigated individual polymer modifiers to date, there is still no comprehensive comparative review examining the effects of different polymer classes on the rheological behavior, compatibility, and long-term performance of bitumen. Therefore, this review aims to provide a systematic and comparative evaluation of polymer additives used in bitumen modification.
Foamed bitumen stabilisation is a sustainable technique for enhancing the mechanical properties of unbound granular materials and rehabilitating aged pavements. This process produces a flexible pavement base and subbase layers with improved mechanical performance and durability. This study investigated foamed bitumen stabilised (FBS) mixtures for pavements in which the aggregate matrix consists entirely of industrial by-products. Three aggregate compositions, including 100% ladle furnace slag (100LFS), 100% electric arc furnace slag (100EAFS) and a combination of 50% EAFS and 50% LFS by mass (50EAFS/50LFS) were used as parent materials for foamed bitumen stabilisation. Alkali-activated fly ash (FA) and slag (S)-based geopolymer was used as a secondary binder to replace conventional carbon-intensive binders such as hydrated lime or cement while enabling rapid strength gain. The mechanical performance of the FBS mixtures was evaluated through unconfined compressive strength (UCS), indirect tensile resilient modulus (ITM r ), repeated load triaxial (RLT) and four-point flexural bending tests, while reinforcement mechanisms were studied using scanning electron microscopy. The results showed that the FBS mixtures incorporating 10%(FA+S) geopolymer achieved higher UCS values than benchmark mixtures with 2% cement, ranged from 4.05 MPa to 20.1 MPa with respected to different aggregate compositions and curing conditions. Two FBS mixtures, 50EAFS/50LFS + 3%B + 10%(FA+S) and 100LFS + 3%B + 10%(FA+S) complied the stiffness requirement for pavement applications, with 50EAFS/50LFS + 3%B + 10%(FA+S) being the optimum mixture and achieved highest ITM r of 4135 MPa and 2685 MPa under unsoaked and soaked condition, respectively. RLT and four-point flexural bending results also showed acceptable performance of the resilient modulus and fatigue resistance of the FBS mixtures incorporating 10%(FA+S) geopolymer. The findings of this study demonstrated the technical feasibility of using steel slag aggregates and geopolymers in foamed bitumen stabilisation for future sustainable road construction, offering improved mechanical properties and durability and a reduced carbon footprint.
This study evaluates the suitability of Kuldana Formation limestone from Nammal Gorge, Salt Range-Potwar Basin, Pakistan, for construction and asphalt pavement applications through integrated petrographic, geotechnical, durability, statistical, and pavement-performance analyses. Fresh, unweathered limestone blocks were collected from intact outcrops and examined using optical microscopy and SEM-EDS to identify mineralogical composition, calcite veining, pore structure, vuggy porosity, and microfracture characteristics. Standardized EN/ISRM/ASTM-aligned laboratory tests were performed to determine mechanical properties, including unconfined compressive strength, unconfined tensile strength, point load index, shear strength, and Schmidt rebound, as well as physical and durability indicators such as specific gravity, bulk density, porosity, water absorption, crushing strength, Los Angeles abrasion coefficient, and freeze-thaw resistance. The limestone showed considerable variability, with UCS ranging from 25 to 98 MPa, UTS from 20 to 80 MPa, water absorption from 0.30 to 0.72%, specific gravity from 1.67 to 2.88, porosity from 1.13 to 2.78%, LA coefficient from 10.31 to 35.20, and freeze-thaw resistance from 14.2 to 60.5. This variability is mainly related to calcite veining, pore-fracture connectivity, vuggy porosity, and microcrack density. Pearson correlation and regression analyses identified coherent relationships among selected physical, mechanical, and durability parameters, while scattered data points reflected defect-controlled responses. Pavement-performance assessment of limestone-aggregate high-stiffness asphalt concrete mixtures showed that the mixtures can satisfy KR7 fatigue requirements and may support limited asphalt-layer thickness optimization, subject to field validation and production quality control. Overall, Kuldana Formation limestone shows promising potential as a construction and asphalt pavement aggregate.