The technical specification TCCS 37:2022 provides guidelines for flexible pavement design based on the Structural Number (SN) concept, developed from the AASHTO 1993 methodology. However, in the context of increasing heavy truck traffic and more demanding service requirements, this specification exhibits several limitations, particularly in terms of standardization, structural configuration control, and its linkage with material properties. This study conducts a comparative analysis of two U.S. pavement design standards, namely the Flexible Pavement Design Manual FDOT FDP, 2026) issued by the Florida Department of Transportation (Florida DOT) and the Pavement Design Manual (ADOT FPD, 2017) issued by the Arizona Department of Transportation (Arizona DOT). The analysis focuses on the SN-based design framework, input parameters, layer coefficients, structural design rules, base grouping mechanisms, and the influence of drainage conditions. The results indicate that FDOT FDP adopts a predominantly tabulated approach with an emphasis on minimum structural control, whereas ADOT FDP maintains a comprehensive mechanistic–empirical framework and establishes a stronger linkage between layer coefficients and material properties. Based on these findings, the study identifies key limitations of TCCS 37:2022 and proposes directions for improvement to support its development into a national standard (TCVN).

The fast drainage of surface water from road pavements is essential to ensure both driving safety and adequate infrastructure service life. For close-graded asphalt mixtures, surface runoff relies on sufficient longitudinal and transverse slopes that convey water toward hydraulic drainage devices. However, construction defects, surface distress, or inadequate placement of drainage systems may compromise this process and reduce pavement durability. When water infiltrates beneath the wearing course and saturates the underlying layers, heavy traffic loads can accelerate deterioration through erosion, pumping, interlayer delamination, and subgrade overstress. This work investigates the joint use of Ground Penetrating Radar (GPR) and Mobile Laser Scanning (MLS) to evaluate drainage deficiencies and detect signs of layer delamination in bituminous pavements. A highway section in Salerno (Italy) was selected as a case study due to known hydraulic-related issues. MLS data were used to reconstruct pavement geometry and model surface runoff patterns, while GPR surveys assessed the condition of the bonding between asphalt and base layers. The results revealed ineffective runoff management and identified multiple areas affected by delamination, confirming a relationship between surface drainage behaviour and subsurface damage. These findings highlight the broader potential of the integrated GPR–MLS framework as a scalable and transferable approach for proactive drainage assessment and structural monitoring in pavement management practices.

While the utilization of waste polymers in asphalt mixtures is widely studied, the specific influence of additive geometry on performance mechanisms remains underexplored. This study presents a multi-scale performance assessment of asphalt mixtures modified with waste Polyvinyl Chloride (PVC) foils. Waste PVC foils were processed into two distinct geometries, "Wiry" and "Random", and incorporated into mixture at dosages ranging from 5% to 12.5% by weight of bitumen via the dry process. At the macro-scale, Semi-Circular Bending, Hamburg Wheel Tracking, Repeated Creep, and Modified Lottman tests were conducted. At the micro-scale, Scanning Electron Microscopy and EDS analyses were employed to investigate interfacial adhesion. The results demonstrated that the "Wiry" geometry significantly outperformed the "Random" by establishing a three-dimensional reinforcement network. Specifically, the mixture modified with 7.5% "Wiry" PVC yielded the highest Flexibility Index of 24.17, representing a 3.7-fold improvement. Furthermore, this optimum dosage enhanced high-temperature stability and maintained moisture resistance (TSR > 85%), whereas dosages exceeding 10% caused agglomeration and performance loss. Microstructural imaging indicated that the fibrous morphology and calcite-rich surface of the "Wiry" additive facilitate superior mechanical interlocking. Consequently, this study suggests that optimizing waste PVC geometry is as critical as dosage for maximizing the durability and sustainability of flexible pavements.

Utilization of industrial paint sludge waste in bitumen mixes for flexible pavements

Material-intensive infrastructure systems, such as flexible pavements, offer significant opportunities for reducing resource consumption and associated life-cycle environmental impacts through design-level interventions. This study integrates structural performance metrics, specifically modulus improvement factor (MIF), into life cycle assessment (LCA) decision-making for pavements. The life cycle carbon emissions of conventional and sustainably reinforced pavements were evaluated. Besides, the inclusion of acidification potential and abiotic fossil resource depletion was evaluated for pavement at the material stage. Further, sensitivity analysis and field verification were performed. Results reveal that material production and manufacturing contribute more than half of total emissions, while transportation contributes to one-third, with the least at the construction stage. A carbon emission reduction factor (CERF) was formulated to compare reinforced and unreinforced materials, demonstrating that geogrid inclusion reduces embodied carbon across all subgrade conditions. The proposed LCA framework demonstrates a practical pathway for structural benefits along with sustainability evaluation into pavement design.

Abstract The construction zones on the highways require a balanced situation that is inclusive of feasibility, safety, environmental accountability and long term efficiency in the maintenance. The current research creates a united approach of feasibility management within highway construction areas through the synthesis of case-based evaluation, life cycle cost analysis and the use of Artificial Neural Networks to predict future maintenance assistance. The research assesses the existing feasibility management as well as evaluates the environmental and safety implication and studies the maintenance strategies that are meant to enhance long-term infrastructure sustainability. The analytical stage involves two highway contexts which include the section of the Aurangabad Highway to Kolwadi Road and the Mumbai-Pune Expressway section. The rigorous and flexible pavements are evaluated comparatively over 30 years with a discount rate of 12 percent and 5 percent inflation rate. The results demonstrate that rigid pavement is more expensive in its initial construction but becomes cost-effective in the long run due to the reduced maintenance needs, and the break-even point is reached in 2029. In one instance, rigid pavement will be 10.39% less expensive than in another, 2048. ANN component will be implemented in MATLAB as a backpropagation feed-forward network with the TRAINLM, LEARNGDM, Mean Squared Error, and 10 neurons in the first layer to help in the future prediction of maintenance cost. The research comes up with a conclusion that a comprehensive approach to sustainable highway maintenance planning includes feasibility assessment, lifecycle economics, safety considerations, and predictive analytics. Keywords: Feasibility Management, Life Cycle Cost Analysis, Artificial Neural Network, Highway Maintenance, Sustainable Infrastructure

The present study investigates sustainable rehabilitation techniques for flexible pavements that utilize waste materials, including scrap tires, polyethylene sheets, and Polyethylene Terephthalate (PET) plastics. It evaluates various innovative techniques such as geo-tire confinement systems to enhance subgrade stability, polyethylene moisture barriers to reduce water penetration, and Thermo-Geo-Plastic (TGP) composites for pothole repair. Laboratory tests reveal that these methods significantly outperform traditional systems, showing increased Marshall stability and flow rates, which enhance load-bearing capacity and flexibility of the pavement. Modified mixtures show approximately 20% improvement in indirect tensile strength and reduced moisture susceptibility. Rutting tests demonstrate reduced permanent deformation and improved fatigue resistance, while permeability tests indicate that the polyethylene interlayers effectively reduce moisture infiltration by 21–60%. The TGP composite achieves compressive strengths of up to 18.81 MPa in field tests, indicating high durability. Microstructural analysis indicates stronger interactions between the aggregate and the binder, thereby improving mechanical properties. Field evaluations validate laboratory results, with noticeable improvements in pavement stability and reduced distress. These sustainable techniques not only improve pavement performance but also reduce waste materials for landfills, decrease embodied carbon emissions, and promote circular economy practices. The study demonstrates that integrating waste materials into pavement rehabilitation can enhance structural reliability, extend service life, and yield substantial environmental benefits.

A static load test, single-wheel load test, and cyclic-wheel load test were carried out on large-thickness flexible base-layer and semi-rigid base-layer asphalt pavement structures by a multifunctional wheel-load testing machine. A comparative analysis was conducted on the influence and mechanism factors, such as load strength, test temperature, and load rate, on the stress and strain at the top and bottom of two asphalt pavement structures. The results show that in the interval of 1.3 MPa ≥ load intensity ≥ 0.5 MPa, with the increase of static load, the transverse strain and vertical strain at the top and bottom of the base layer of large-thickness flexible base-layer asphalt pavements increase slowly with a slight increase; the transverse strain and vertical strain at the top of the base layer of large-thickness semi-rigid base-layer asphalt pavements are more sensitive to heavy traffic load; and the transverse strain and vertical strain generated at the bottom of the base layer increase uniformly with the enhancement of static load. Under the action of a single-wheel load, the transverse and vertical strain generated at the top and bottom of the base layer of large-thickness flexible base-layer and semi-rigid base-layer asphalt pavements are alternately tensile and compressive, mainly compressive strains, while large-thickness semi-rigid base-layer asphalt pavement exhibits more complex strain changes.

Influence of Cement and Lime Treatment On the Resilient Modulus and Permanent Deformation of Weak Subgrade in Flexible Pavement

Physical performance of flexible pavement system with and without a Portland-cement-concrete (PCC) slab for geofoam embankments

Influencing factors, durability and mechanical performance of geopolymer binders in flexible pavement applications: a state-of-the-art review

Rutting represents a severe, cumulative symptom of structural distress in flexible pavements, which occurs due to the accumulation of permanent deformation when subjected to repeated traffic loads and therefore adversely influences the quality of the ride, safety, maintenance life and costs. This study assesses the influence of the pavement layer thickness on the rutting depth using the three-dimensional finite element modeling (FEM) in the ABAQUS computing program. The flexible pavement system was built as a detailed numerical model with realistic material properties, nonlinear constitutive behavior and repeated loading in a static situation. There were nine pavement designs which varied in terms of the thickness of asphalt wearing course and base course, and evaluated stress distribution and permanent deformation. The findings showed that adding the pavement layer thickness has a significant effect on rutting depth, which is reduced due to the spreading of loads and the strain concentrations, especially in the asphalt and subgrade layers. On the other hand, thinner pavement layers had a greater deformation and they experienced faster rates of rutting at the same loading conditions. The results offer useful mechanistic information about the rutting behavior and contribute to the optimization of layer thickness of pavements to increase durability, sustainability and long service performance.

Overlay design for flexible pavements requires normalisation of surface deflections and back-calculated modulus values obtained from falling weight deflectometer (FWD) testing to a reference temperature using appropriate correction models. Existing temperature correction models are primarily calibrated for conventional asphalt mixtures without additives and reference temperatures between 20 °C and 35 °C, limiting their applicability in tropical climates. In recent years, the incorporation of waste low-density polyethylene (wLDPE) in asphalt mixtures has emerged as a sustainable solution for plastic waste management. This study investigated the temperature susceptibility of flexible pavement sections constructed with bituminous concrete (BC) wearing courses containing varying wLDPE dosages (0%, 4%, 6% and 8%) using the dry mixing process. FWD evaluations were performed at pavement temperatures ranging from 30 °C to 50 °C. The results indicate that wLDPE-modified mixes exhibit significantly lower temperature susceptibility compared to conventional mixes. Based on in-situ deflection data and mix characteristics such as air voids, layer thickness, binder content and wLDPE dosage, upgraded temperature correction models were developed to normalise FWD measurements to reference temperatures within the tropical range of 20 °C–50 °C. Statistical analysis confirmed that the proposed models more accurately capture the reduced temperature sensitivity of wLDPE-modified mixes. These models provide a practical framework for improving overlay design reliability for asphalt layers incorporating wLDPE under high-temperature conditions.

A Systematic Review of Life Cycle Assessment and Cost Optimization in Flexible Pavement Engineering

Introduction: The increase in industrial activities and urbanization has led to higher amounts of waste such as fly ash, slag, plastic waste, and construction debris, which may cause environmental problems. The utilization of these wastes in pavement construction offers a sustainable solution to reduce waste accumulation and the use of natural resources. Objective: This article aims to analyze research trends on the utilization of industrial and domestic waste as sustainable pavement materials. Method: This study employed a literature review of 15 scientific articles retrieved from Google Scholar, analyzed based on waste type, pavement type, technical performance parameters, and environmental aspects. Results and Discussion: The findings show that fly ash is the most studied waste material, followed by slag, plastic waste, and recycled concrete aggregate (RCA). Most studies focus on flexible asphalt pavements using parameters such as Marshall Stability, compressive strength, and CBR. Proper waste incorporation improves technical performance while reducing natural aggregate consumption and waste disposal. Conclusion: The use of industrial and domestic waste in pavement construction has strong potential to support sustainable infrastructure development, although more integrated technical and environmental evaluation is still needed.

ABSTRACT A flexible pavement is typically idealised as a layered elastic system for analysis purposes. Existing formulations and algorithms often assume a circular contact area with a uniform pressure distribution between the tire and the pavement, leading to an axisymmetric analysis. However, evidences from experimental and numerical studies show that the geometry of the contact area is not necessarily circular, and the pressure distribution is not necessarily uniform. In this work, an approach is developed that accommodates any geometry of contact areas and pressure distributions using the Fourier transform approach. The results are computed numerically and validated against those obtained from finite element analysis. The method offers an advantage of reduced computational cost compared with conventional finite element method simulations.

ABSTRACT Cracking remains a critical challenge in flexible pavements, particularly after long-term oxidative ageing of asphalt binders. This study evaluates the cracking susceptibility of twelve unmodified binders from domestic and international sources under extended ageing conditions (20, 40, and 60 h in a pressure ageing vessel). Despite similar grading, significant variability in chemical composition and performance was observed. Cracking behaviour was characterised using the Superpave fatigue factor (G*·sinδ), Linear Amplitude Sweep (LAS), and Double-Edge Notched Tension (DENT) tests. Complementary chemical analysis using SARA fractions and the Gaestel index (GI) revealed systematic compositional shifts, with decreasing aromatics and increasing resins and asphaltenes, resulting in higher GI values. While fatigue parameters showed a decline with ageing, their correlation with GI was inconsistent. In contrast, crack tip opening displacement (CTOD) from the DENT test exhibited a strong and mechanistically consistent correlation with GI (R² = 0.73), effectively distinguishing resilient and embrittled binders. The findings highlight the limitations of fatigue-based parameters and establish CTOD as a reliable chemo-mechanical indicator of cracking susceptibility. Adoption of DENT-based evaluation is recommended for improved durability assessment.

Wandering constraints in autonomous vehicle platoons to safeguard flexible pavements

Pavement wear in tropical areas stemmed from intense rainfall, varying traffic volumes, and scarce upkeep funds, so solid evaluation techniques were essential for smart maintenance scheduling. In this work, we compared three key methods for assessing pavement condition: the Pavement Condition Index (PCI), Surface Distress Index (SDI), and Indonesia’s Bina Marga standard, all tested on one flexible pavement stretch. What set this study apart from earlier research mostly focused on a single approach, was its examination of how these methods differed in sensitivity, their impact on decision-making, and how consistently they aligned when applied to the same road section. We divided a 660-meter portion of Wangandawa Road into seven 100-meter segments and surveyed them using standard visual inspections for pavement distress. PCI scores ranged from 45 to 100 (average 71.0), indicating conditions from fair to excellent and showing sharp differences between segments. SDI scores ranged from 0 to 80, classifying conditions as good to moderate, whereas the Bina Marga method classified every segment under Priority A maintenance, showing no variation. When we compared the three approaches, PCI proved more sensitive in identifying fine-scale distress patterns, while SDI and Bina Marga demonstrated greater practicality for rapid network-level assessments. These findings supported the continued use of visual inspection methods for pavement evaluation in tropical regions and highlighted the importance of selecting an appropriate index for practical decision-making. PCI was suitable for detailed planning of rehabilitation and reconstruction, whereas SDI or Bina Marga were more suitable for quick assessments and routine maintenance planning.

Numerical study on the effect of geogrid reinforcement in flexible pavements