Flexible Pavement Structures Research Articles

Evaluation of potential electric vehicles load-induced damage on flexible pavements

The adoption of Electric Vehicles (EVs), driven by policies like the Zero Emission Vehicle (ZEV) mandate, is rapidly transforming transportation infrastructure. In 2021, over 1.25-million light-duty EVs were registered in the United States, signaling a shift that extends to heavy vehicle categories. This study evaluates the implications of this transition on road networks, focusing on the increased gross weight of EVs compared to traditional Internal Combustion Engine (ICE) vehicles and its impact on flexible pavement structures. The study investigates the deterioration patterns and potential damage to road infrastructures resulting from integrating EVs into the traffic mix, utilizing both the AASHTO 1993 and Mechanistic-Empirical (ME) pavement evaluation methodologies. The analyses reveal a significant acceleration in road degradation, necessitating urgent consideration of EV-induced stresses by transportation authorities. Recommendations for future research and practical strategies for mitigating these impacts are provided to guide policymakers and engineers in adapting to this evolving vehicular landscape.

Temperature Effects on Traffic Load-Induced Accumulating Strains in Flexible Pavement Structures

AbstractRutting is a major distress mode in flexible pavements, results from the repetitive loading caused by traffic movement. Pavement deformation consists of both recoverable (elastic) and unrecoverable (plastic) components. The continuous movement of vehicles contributes to the overall deformation in the flexible pavement system, involving all pavement components. In regions with hot climates or in the hot summer season, rutting tends to be more prominent due to the substantial reduction in the viscosity of the asphalt binder. This decrease in viscosity, which is inversely linked to rutting, occurs as temperatures rise, leading to a heightened susceptibility of the Hot Mix Asphalt (HMA) blend to rut formation. However, according to studies, a significant amount of permanent deformation takes place in the unbound layers beneath the asphalt course, it is therefore essential to prioritize attention on these layers. Temperature exerts besides viscosity a substantial impact on asphalt stiffness, leading to the transfer of higher vertical deviatoric stresses to the unbound layers beneath the asphalt course (base, subbase, subgrade). This research presents a study integrating the High Cycle Accumulation (HCA) model into a laminar model to determine permanent deformations in the unbound granular layer of flexible pavements and taking into account the temperature dependent stiffness of asphalt. Rutting depths at the end of the design lifetime were computed, accounting for seasonal stiffness variations. It was shown that the softer asphalt behavior significantly increases the development of ruts in the underlaying soil layers. The findings were compared with results obtained from mean annual temperature and the typical equivalent asphalt stiffness utilized in fatigue tests. Additionally, an analysis was conducted to assess whether the timing of road implementation influences settlements throughout the design lifetime. The results suggest that the sequence of seasons is most relevant during the first year of service, showing a distinct effect at that time. However, with a higher number of axle passes, the initial differences fade away, and the curves start to merge.

Machine learning modelling the rut depth of WMA mixtures with variable reclaimed asphalt pavement (RAP) and foamed bitumen content

ntroduction. Rutting of flexible, super flexible and semi-rigid pavement structures is a typical and frequently decisive condition parameter, form of pavement deterioration. That is why, any research result in the field can have of high importance for the road engineers. Problem Statement Rutting poses a significant challenge to asphalt pavements, causing permanent deformation under heavy loads, particularly in warm and wet conditions. Purpose. This pavement distress type has — in addition to riding comfort challenges — important traffic safety consequences (e.g. aquaplaning), as well. The research work concentrates on the influence of the use of warm mix asphalt, reclaimed asphalt material and foamed bitumen binder on the rut depth of asphalt pavements.

Study of the Influence of the Variability of Traffic-Related Parameters on the Service Life of Flexible Pavement Structures in Senegal by a Mechanistic-Empirical Approach

The results of the study showed that exceeding the axle load and axle configuration are indisputably among the most damaging factors for flexible pavement structures in Senegal, made of local materials (Diack basalt, Sindia laterite). The regulatory axle load recommended by UEMOA for users is set at 11.5 tons and 12 tons for a single and twin axle respectively. For calculation purposes, this load is set at 13 tons. However, in Senegal, this axle load is often exceeded, and given the diversity of heavy goods vehicles in traffic, single axles, whose effects, according to several authors, are more detrimental to flexible pavement structures, are increasingly observed in road traffic. Differences in fatigue cracking and rutting damage between single and dual wheels, as well as load overruns, show the need to take axle configuration and possible overloads into account when dimensioning flexible pavement structures in Senegal, and when planning their maintenance, the costs of which are excessively high, according to Senegal's Autonomous Road Maintenance Fund (FERA). Keywords: Single wheel, dual wheel, damage, fatigue cracking, rutting, traffic

Investigation of the effect of re-refined engine oil bottom on asphalt mixture performance and ecological implications

ABSTRACT This study explores the use of re-refined engine oil bottom (REOB) as an alternative to bitumen in asphalt mixtures for flexible pavement structures. REOB is considered due to its low cost, availability, large production volume, and eco-friendliness. This paper investigates the effects of adding 5, 9, and 14 wt% of REOB to neat bitumen on the asphalt mixture’s characteristics, mechanical behaviour, and ecological implications. The findings reveal significant reductions in indirect tensile strength by up to 51%, moisture resistance by up to 17%, rutting resistance by up to 79%, and cracking resistance at intermediate and low temperatures, especially when 14 wt% of REOB is added. While the heavy metal concentrations in both bitumen and REOB exceed permissible limits, the leached metal concentrations from the asphalt mixture remain within the safe range. Despite the potential environmental benefits of using REOB, the economic evaluations suggest that incorporating REOB into asphalt mixtures slightly increases the construction cost. Therefore, careful economic consideration should be performed for each project.

Impact of confinement condition of dynamic modulus test on the performance of flexible pavement structures

Impact of confinement condition of dynamic modulus test on the performance of flexible pavement structures

Prediction of Damage and Remaining Life of Yogyakarta-Bawen Toll Road Pavement with Elastic and Viscoelastic Approaches

Toll roads are one of the infrastructure development targets in Indonesia to speed up traffic and vehicle travel times. This paper analyzes the flexible pavement structure of the Yogyakarta-Bawen Toll Road. It predicts damage and residual values using elastic and viscoelastic approaches based on MDPJ Bina Marga 2017 using the KENPAVE Program. The recommended design alternative is pavement with a layer of AC-WC 40 mm, AC-BC 60 mm, Base AC 180 mm, and LPA 300 mm. This alternative is predicted to be able to serve load repetitions in the elastic approach of 432,857,828 ESAL until fatigue cracking occurs, 215,176,089 ESAL until rutting occurs, and 136,575,580 ESAL until permanent deformation occurs. Analysis using the viscoelastic approach can provide load repetitions of 153,304,378 ESAL until fatigue cracking occurs, 47,014,109 ESAL until rutting occurs, and 71,859,938 ESAL until permanent deformation occurs. Based on the elastic approach, the pavement's service life is 33 years, with initial damage in the form of permanent deformation. In comparison, the viscoelastic approach has a service life of 22.7 years, with initial damage in the form of rutting.

Graph Neural Networks to Simulate Flexible Pavement Responses Using Three-Dimensional Finite Element Analysis Data

The significant computational costs and efforts required for accurate three-dimensional (3D) finite element (FE) pavement response calculations necessitate an expedited approach. This study proposes a graph neural network (GNN)-based simulator for the modeling of 3D pavement structural responses under tire loading. The GNN model was trained using 240 simulations of 3D pavement FE data of flexible pavement structures. The simulator represented the state of pavement structure meshes in FE analysis at any given timestep as a graph, with FE nodes encoded as graph nodes and mesh edges as graph edges. The dynamic behaviors of pavement FEs were computed via learned message-passing between two graphs within two continuous timesteps. The one-step mean squared error (MSE) and rollout MSE were used as evaluation metrics for the GNN model. The results showed that, given an initial state of FE responses, the model could perform accurate one-step predictions, extending to trajectory predictions with one-step MSE as low as [Formula: see text] and rollout MSE around [Formula: see text]. The prediction framework is efficient; it requires a week of model training but only a mere 5 min of prediction for each single case. This a contrast to traditional 3D FE analyses that can span hours to weeks for a single case. The hyperparameters, including the number of message-passing steps M and the number of historical timesteps C, were established as 10 and 1, respectively, based on model performance and computation time. It was also observed that data normalization before training could significantly reduce model simulation noise.

Evaluating Stabilizing Effects of Geosynthetics in Flexible Airport Pavement Structures by FE Analyses

Evaluating Stabilizing Effects of Geosynthetics in Flexible Airport Pavement Structures by FE Analyses

Effects of short-term aging on the mechanical and structural performance of hot mix asphalt mixtures: a case study complemented by statistical analysis

This study aimed to assess the effects of short-term aging on the mechanical behaviour of asphalt layers of flexible pavement structures. The effects of aging on their mechanical performance have not yet been detailed, in terms of structural analyses. Therefore, pavement structures with distinct types of asphalt layers (non-aged and aged) were evaluated. Stability, tensile strength, resilient modulus, fatigue behaviour and permanent deformation or static creep were determined. The mePADS software was used to carry out structural analyses of the pavements, based on variations in the bound layers’ mechanical properties, loading level and tire inflation pressure. Horizontal stresses and strains were determined at the bottom of the binder course. Fatigue lives were predicted and discussed based on statistical analyses. The short-term aging enhanced the mechanical parameters, but adversely affected the fatigue life for the examined strain states, which reinforces the importance of carrying out the structural analyses.

Life cycle assessment and pavement performance of recycled aggregates in road construction

Integrating environmental goals in the construction of infrastructure has attracted great attention over the past two decades. The use of construction and demolished waste materials (C&D) as a base layer for pavement structures gained popularity as a sustainable alternative to virgin aggregates (VA). An experimental testing program was designed to investigate several recycled materials as a potential replacement to VA in flexible pavements base layer. The testing program included routine tests, matric suction, static, and repeated load triaxial tests to measure the general engineering properties and evaluate the material performance under static and cyclic loading. The results of the laboratory testing program were employed to predict the pavement performance utilizing different combinations of C&D waste as a base layer for flexible pavement structures using the AASHTOWare Pavement ME Design at different climate conditions. The sustainability of using C&D material as a partial or full replacement of VA base material in pavement construction was evaluated by using the life cycle assessment (LCA) approach. The results showed that all the C&D materials yielded a much thinner base layer compared to the natural VA achieving the same pavement performance. Moreover, the reduction in the thickness is more significant in cold and wet climatic conditions rather than the hot and dry climatic conditions. LCA results revealed that the VA base layer had the highest environmental impact on all tested categories. VA materials, used as a base layer, show 65% higher global warming potential compared to C&D materials as a base layer in all climatic conditions.

The Effect of Axle Overloading and High Tire Pressure on Flexible Pavement Structure

Axle overloading and high tire pressures on the highways and motorways in Pakistan are one of the reasons that cause early pavement deterioration. There are numerous sections on the national highway on which trucks are reposted to be operating at 40-80 percent higher tire pressure than the legal limit, and the axle overloading is 30 percent greater than the legal axle load limit. This research aims at determining the effect of axle overloading and high tire pressure on the flexible pavement structure and derive the truck factors for trucks in order to quantify the damage to the pavement due to a single pass of 2-axle, 3-axle, 4-axle, 5-axle, and 6-axle truck using the results reported in the Pilot Axle Load Survey conducted by the National Transport Research Centre. In order to determine the effect of axle overloading and high tire pressure, a theoretical linear elastic mechanistic empirical analysis for different axle configurations was performed using KENLAYER and regression models were developed to find the Equivalent Axle Load Factor (EALFs) for the fatigue cracking, and permanent deformation. It was found that the EALFs were mostly controlled by permanent deformation distress criterion. The EALFs and the truck factors were highly influenced by the axle loads rather than the tire pressure. The 3-axle truck was found to be the most damaging truck followed by 6-axle truck, 5-axle truck, 2- axle truck, and 4-axle truck.

Analysis of Flexible Pavement Structural Behavior Considering Decreased Subgrade Resilient Modulus

This research focuses on the subgrade resilient modulus and its significance in investigating flexible pavements. The study compares results obtained from two distinct flexible pavement structures, utilizing numerical analysis using FLAC3D softawere. Four decreasing levels of subgrade resilient modulus (PF50, PF25, PF10, and PF5) were examined. Our findings reveal that the decrease in subgrade resilient modulus has a more pronounced effect on the GB/GB structure compared to the GB/GNT structure, with the latter demonstrating superior performance. By assessing subgrade resilient modulus, this research contributes to a better understanding and improving road infrastructure investigation not only in Algeria but also in broader contexts

SUBSTANTIATION OF THE ROAD CONSTRUCTION UNBOUND MATERIALS CALCULATION MODEL WITH GEOGRIDS STABILIZATION

Summary. Based on the results of experimental studies conducted on different types of flexible pavement structures, the authors of the article examined the behavior of unbound material reinforced with geogrid. A series of static plate load tests were carried out, and the deformation modulus values of traditional and reinforced pavement structures were determined. The impact of the geogrid, installed at the base of the unbound layer of the pavement structure, on its deformation modulus was investigated. It was found that the use of geogrids significantly increases the equivalent deformation modulus of the pavement, depending on the thickness of the inert material layer and the deformation characteristics of the subgrade soil. The effectiveness of the reinforcement depends on the ratio of the deformation characteristics of the pavement and the subgrade soil, as well as the relative depth of the geogrid installation. The greatest effect is achieved on weak soils under large deformations. The results obtained are significant for further research and practical application of pavement reinforcement technology using geosynthetic materials. Keywords: highway, pavement structure, biaxially oriented geogrid, geosynthetic reinforcement, plate load tests, deformation characteristics, loading, reinforcement coefficient, field experiment

Pavement design using bituminous surface course with recycled aggregates

The utilization of Recycled Aggregates (RA) in the construction of pavement structure is one of the inventive and eco-friendly construction techniques. This scale down the construction cost without negotiates the strength and the durability of the pavement structures. However, RA is rigid in nature because it is obtained from aged bituminous mixtures to enhance a rejuvenator is usually added in order to lower the stiffness. Rejuvenator surges the utility of the bituminous mixtures and makes them be smoothly paved and compacted. The objective of this study is to design a flexible pavement structure using Stone Matrix Asphalt (SMA) as a surface course in order with RA. In SMA mixture major component is occupied by coarse aggregates, mineral filler, bitumen and a minor component of fine aggregates helps to fill the voids present in coarse aggregate which gives stone-on-stone contact. The bitumen binder and mineral filler form mastic, providing durability to the mixture. In this study, the performance of SMA mixtures with different RA proportions and a rejuvenator will be compared with conventional SMA mixture with zero percentage RA. Marshall Mix design is outlined to find the Marshall and volumetric properties of SMA mixtures and to regulate the Optimum Binder Content (OBC). The mixtures will be compared based on the drain down, stripping, Indirect Tensile strength (ITS) and Semi circular bend (SCB) test results. The analysis and design of flexible pavement structure using the prepared SMA mixtures with different RA contents as surface courses also will be carried out as a component of the study.SMA mixture of 40% replacing RA with 3% of palm sludge oil as rejuvenator exhibits optimum bitumen content where vertical stress, strain and displacement obtain reduction with compared to IRC 37 conventional SMA mixture.

Pavement rutting performance analysis of automated vehicles: contribution of flexible pavement layers’ characteristics

Designing and implementing appropriate pavement structures in the era of coexisting automated vehicles (AVs) and human-driven vehicles (HDVs) is a significant concern for researchers and road practitioners. This necessitates investigating the pavement performance subjected to the various loading distribution scenarios induced by different lateral movement patterns of AVs. It is known that the pavement layers' thickness and material influence pavement performance. This study used a finite element method (FEM) to model AVs' loading distributions and simulate the rutting performance of a full-depth flexible pavement structure constructed in different layers' thicknesses and materials. The results revealed that the layers' thickness and material contribution depend on the lane distribution scenario and the AVs' wander mode. In some AV scenarios, improving the layers' material and increasing the thickness could help reduce the pavement rutting damage compared to HDV scenarios, with the extent of this effect influenced by AVs' wander mode.

Effect of Cement Content and Aggregate Gradation on Compressive Strength, Flexural Strength, and Elastic Modulus of Cement-Treated Base

Cement-treated base (CTB) is an aggregate mixture with relatively low water and cement content for pavement base layers, which can provide a stronger and stiffer base layer and requires a lower thickness than using granular layers but has the potential to form reflective cracks in the surface layer. Therefore, CTB should not be too stiff and the compressive strength needs to be limited. The research was carried out to analyze the effect of variations in cement content, gradation, and mix density on compressive strength, flexural strength, and elastic modulus. This research also analyzed the resistance of flexible pavement structures with CTB to asphalt fatigue and permanent deformation failure using the AUSTROADS 2017 method and the CIRCLY 6.0 program. The stiffness of CTB with Bina Marga gradation is built by the aggregate material (initially stiff), while the stiffness of CTB with FAA gradation is built by cement and the aggregate material tends to give flexible behavior because it is easier to move. The results showed that CTB with FAA gradation and 5% cement content resulting in a 7-day compressive strength of 3,28 MPa was stated as the optimum mix combination because it provides better resistance to fatigue and permanent deformation failure.

Flexible Road Pavement Thickness Planning using the 2017 Manual Road Pavement Design (MDPJ) Method and 1987 Component Analysis on the Jepara - Keling Road Section

The increase in the volume of vehicles on the Jepara - Keling road has resulted in a decrease in the quality of road services, moreover, it has been exacerbated by the passing vehicles which often exceed their carrying capacity, thus accelerating road damage. Therefore, road planning efforts are needed to maintain road function from various potential damages that occur. The purpose of this thesis is to plan a flexible pavement thickness that is able to serve the volume of vehicles and withstand the loads of passing vehicles. Meanwhile, before planning a road, it is necessary to know the condition of the road, field CBR data, average daily traffic data and also need to plan what material the road will be built with. The approach method used in planning the thickness of the flexible pavement is using the 2017 Road Pavement Design Manual (MDPJ) method and the 1987 Component Analysis method. Based on the calculations that have been carried out, it is obtained that the thickness of the flexible pavement structure design is obtained for each layer using the Road Pavement Design Manual (MDPJ) method. ) 2017 are as follows: for 4 cm thick AC-WC layer, 6 cm thick AC-BC layer, 16 cm thick AC-Base layer, and 30 cm thick Class A LPA layer. Whereas using the 1987 Component Analysis method, the thickness for each layer was obtained as Asphalt Concrete MS 740: 10 cm, Class A Crushed Stone LPB: 25 cm, Class A Sand and Stone LPB: 22 cm

Comparative Study of Performance between International Roughness Index (IRI), Pavement Condition Index (PCI), and Bina Marga Method on Roadways

In this research, a comparative study is conducted between the International Roughness Index (IRI), Pavement Condition Index (PCI), and Bina Marga method on roadways with a flexible pavement structure. The objective is to compare the results of road damage evaluation using these three methods and formulate appropriate treatment programs. The research findings indicate that overall, the IRI method provides an overview of the road surface roughness level. The majority of the analyzed data falls under the "Moderate" category with a value of 7.2. The PCI method measures the physical condition of the road infrastructure, which is categorized as "Fair" with a value of 41.2. On the other hand, the Bina Marga method assesses the type of road maintenance, which is categorized as "Routine Maintenance" with a value of 6.8. Enhancing road maintenance practices is necessary to address minor damages such as small cracks or surface irregularities that affect road user comfort.

Calculation Method for Traffic Load-Induced Permanent Deformation in Soils under Flexible Pavements

Rutting is one of the most common types of distress in flexible pavement structures. There are two fundamental methods of designing pavement structures: conventional empirical methods and analytical approaches. Many analytical and empirical design procedures assume that rutting is mostly of asphalt origin and can be reduced by limiting the vertical deformation or stress at the top of the subgrade, but they do not quantify the rutting depth itself. Mechanistic–empirical models to predict the permanent deformations of unbound pavement layers have been well investigated and are rather common in North America; however, they are not widely utilized in the rest of the world. To date, there is no generally accepted, widely recognized, and documented procedure for calculating permanent deformations and thus for determining the rutting depth in flexible pavement courses originating from the unbound granular layers. This paper presents a layered calculation method with which the deformation of soil layers (base, subbase, and subgrade courses) under flexible pavements due to repeated traffic load can be determined. In the first step, the cyclic strain amplitude is calculated using a nonlinear material model that is based on particle size distribution parameters (d50 and CU) and dependent on the mean normal stress, relative density, and actual strain level. In the second step, the HCA (High Cycle Accumulation) model is used to calculate the residual settlement of each sublayer as a function of the number of cycles. It is shown that the developed model is suitable for describing different types of subgrades and pavement cross-sections. It is also demonstrated with finite element calculations that the developed model describes both the elastic and plastic strains sufficiently accurately. The developed model can predict the settlement and rutting of pavement structures with sufficient accuracy based on easily available particle size distribution parameters without the need for complex laboratory and finite element tests.