Design Of Pavement Structures Research Articles

Evaluation on Fatigue Life of Expressway Asphalt Pavement Based on Tire-Pavement-Subgrade Coupling Model

The fatigue failure has become one of the main failure modes in asphalt pavement of expressway. However, due to the material nonlinear of the tire, pavement and subgrade, the contact nonlinear of tire-pavement and the influence factors, such as the tire inflation pressure, rotation speed, wheel load, the values and distributions of contact stress between tire and pavement are extremely complex and affect the tensile stress and tensile strain, as well as affect the wear, deformation and fatigue life of pavement. The three dimensional (hereinafter referred to as 3D) finite element model of tire-subgrade-pavement structure was established, and the steady-stable rolling of tire and stress-dependent dynamic resilient modulus of subgrade soil were considered in the model．Based on the mixed Euler-Lagrange describtion, the steady-state finite element analysis were carried to indicate the mechanism of fatigue cracking of asphalt pavement, the influences of rolling resistance of wheel, friction coefficient, axle load, tire pressure and running velocity on fatigue lives were discussed based on the tensile strain fatigue prediction model. The results show that the fatigue life of pavement decreases with the increasing rolling resistance of wheel, friction coefficient, wheel load and tire pressure, and it does not obvisouly depend on the running velocity. The study could provide a reference for the design of the flexible asphalt pavement structure and the evaluation of pavement fatigue life.

Temperature Change Implications for Flexible Pavement Performance and Life

The temperature of the asphalt concrete AC is one of the most important environmental factors that influences flexible pavement performance. The possibility hazard of temperature change raises attention in how it may affect the deterioration rates (deflection, strain and stress distributions) in flexible pavement and how pavement service life would be changed as a result. A change in the AC temperature directly influences the stiffness of the asphalt-bound layers, which modifies the stress statues inside the pavement. This alteration in stress can influence the stiffness of the underlying unbound layers since they generally show stress reliance. Due to these relations are nonlinear, the additional pavement life lost at higher than average temperature is not replaced by savings at lower than average temperature. For that, the deterioration amount are overvalues when average pavement temperatures are used for determining the asphalt stiffness. The objective of this research was to study the pavement temperatures throughout the year in Egypt on performance and life of seven pavement sections with different stiffness or thickness using mechanistic-empirical method to investigate the most influential characteristic under temperature change for improving the design of pavement structures. The results revealed the significance of the impact that climate change may have on the performance service life of flexible pavements. These changes may impact the pavement life cycle cost and thus their impact on future maintenance requirement should be investigated.

Integrating the Dynamic Modulus of Asphalt Mixes in the 1993 AASHTO Design Method

The AASHTO Guide for Design of Pavement Structures 1993 (1993 Design Guide) remains the most widely used pavement design manual by highway agencies and design consultants around the world. As defined in the 1993 Design Guide, the structural coefficient of a pavement layer ( ai) is an abstract measure of the relative ability of a unit thickness of a given material to function as a structural component of the pavement. Nevertheless, the assumed ai values of the asphalt layers and a proposed relationship between ai and the resilient modulus do not account for the mechanical and physical properties of asphalt materials, traffic volume and speed, layer thicknesses (thin versus thick pavements), climate, and unbound layer properties. The purpose of this research was to enhance the design methodology incorporated in the 1993 Design Guide by integrating asphalt mixture properties in the design process. The objective was to devise a relationship between the structural coefficient ( ai) of the asphalt layer and the effective dynamic modulus (|E*|eff.) of the corresponding asphalt mix to yield a more realistic estimate of the structural capacity of the asphalt layer. The paper illustrates the development of a multilinear relationship between ai, (|E*|eff.), and the resilient modulus of the aggregate base layer. Pavement structural designs for various asphalt mixes and design inputs using the developed ai–(|E*|eff.) relationship yielded asphalt layer thicknesses that were generally smaller than those obtained using the typical ai value of 0.44 for the asphalt layer and closer to thicknesses obtained with the AASHTO mechanistic–empirical design method using the Pavement ME software.

Pengaruh Substitusi Abu Batu (Quarry Dust) Pada Nilai CBR Laboratorium Untuk Stabilitas Subgrade Timbunan

Quarry dust (dust mine) is a non-plastic materials from the rest of quarry stone crusher machine in range size are 0 - 5 mm. Production of quarry dust in Indonesia is very abundant. A stone crusher in the maximum work can be produced quarry dust up to 4 tons per hour. The use of quarry dust now is still less optimal. Its only used as a filler in the surface layer of pavement. So that , there are more innovation in use of quarry dust to balance between produce and use. One uses the quarry dust isfor soil stabilization.Soil stabilization is the engineering effort to improve the quality of the soil is not good and improve the quality of the soil that has actually been quite good.In pavement structural design, not all subgrade base having a good CBR value, it was low in CBR rate and it must be replacement, repair or soil stabilization. This experimental study was conducted in Soil Mechanics Laboratory Departement Civil Engineering University Technology Yogyakarta. Object research aresoil water content and soil density to determine the optimum soil water content. This amount water will added in to mixture of stone dust (quarry dust) 0%, 5%, 10%, 15 % and 20% and this variation test will be aging for 48 hours. Results this research indicates that5% quarry dust added to the mixture will gave the optimum CBR amounted to 26.20%. That amount represents an increase of 19.01% from the design CBR native land by 22%.

Traffic Assessment for Pavement Structural Design Using RN29, LR1132, and HD26/01 Methods

Traffic surveys are means of obtaining information about the traffic characteristics of an area. The data collected is used for traffic assessment of the area for various Engineering purposes. This study was an attempt to conduct a traffic assessment for the purpose of pavement design. Three design methods: Road Note 29 (RN 29), Laboratory Report 1132 (LR 1132), and Design manual for Highways and Bridges (DMHB; HD 26/01), were adopted. Three locations along the Onitsha-Enugu expressway, a Nigerian interstate highway, were surveyed. The highest volume of commercial vehicles was observed at the Nkpor location with corresponding design traffics of 108msa, 304msa, and 92.92msa using RN 29, LR 1132, and HD 26/01 respectively. Computed design traffics for Nkpor, Awkuzu, and Kwata locations using LR 1132 were 304msa, 175msa, and 167msa respectively. These were found to be significantly higher than those computed using RN 29 and HD 26/01 due to the fact that a uniform damaging factor was computed for the entire traffic count without any form of categorization or weight impact discrimination. It was concluded that the traffic assessment method to be adopted for any pavement design purpose should be consistent with the design method to be used for the selection of pavement thicknesses.

Design of Frost Resistant Pavement Structure Based on Road Weather Stations (RWSs) Data

Frost is a decisive factor influencing pavement performance in cold countries. In the EU, millions of euros are spent annually on winter maintenance. About one-third of the maintenance budget is allocated to rehabilitation due to the negative impact of frost. The negative effect of frost is restricted by using non-frost-susceptible materials within the frost zone and regulating water accumulation. However, experience shows that the thickness of constructed pavement structure is often inadequate and that frost penetrates into the subgrade of frost-susceptible materials. The aim of this paper is to introduce the thickness calculation approach of the frost resistant pavement structure using road weather station (RWS) data. The subgrade susceptibility to frost and the number of equivalent single axle loads (ESALs) are considered as factors too. The calculated thickness of the frost resistant pavement structure is corrected according to the specific local conditions. After performing a statistical analysis of 2012–2014 data pertaining to 26 RWSs, Lithuania was divided into four regions according to the maximum frost depths, where the maximum values depending on RWS location varied from 110.4 cm to 179.1 cm.

Determination of Stiffness Modulus and Poisson's Ratio of Lightly Stabilized Granular Materials From Indirect Diametral Tensile Testing

Lightly cementitiously stabilized granular materials are generally characterised by their tensile properties that are required for the analysis and design of a pavement structure involving these materials. Tensile properties include tensile strength, stiffness modulus, and Poisson's ratio. However, there are limited studies on the mechanistic determination of stiffness modulus and Poisson's ratio of lightly stabilized materials; rather, a magnitude of Poisson's ratio is often assumed. This paper examines the use of monotonic and cyclic load indirect diametral tensile (IDT) testing to determine the Poisson's ratio and stiffness modulus of lightly stabilized granular materials. The experimental program included the determination of IDT strength, static and dynamic stiffness modulus, and Poisson's ratio for a typical freshly quarried granular base material stabilized by the addition of 0.5 to 3 % cement-flyash and 1.5 to 3 % slag-lime slow-setting binder. A new IDT testing setup to measure both the horizontal and vertical deformations along the diameters of an IDT specimen was developed and the tests were conducted on 28 days cured samples prepared by gyratory compaction. Details of the new IDT testing arrangement with on-sample deformation measurement for performing monotonic and cyclic load testing to obtain reliable data are discussed. This study indicates that the proposed IDT testing setup with on-sample deformation measurement could be used reliably for determining the tensile properties of lightly stabilized granular materials including the Poisson's ratio.

Characterizing Stress–Strain Relationships of Asphalt Treated Base

AbstractIn a flexible pavement, the base course is an essential component in that it supports the surface course and distributes traffic loads to the subbase and subgrade. Asphalt treatment is used on granular base course material to enhance the material’s properties and overcome its deficiencies. Due to its lower binder content and lower-quality granular material, asphalt treated base (ATB) exhibits a stress–strain relationship unlike either regular granular material or hot mix asphalt. Stress−strain relationship is the primary fundamental material property used for mechanistic-based pavement structural analysis and design. However, current guidance for choosing the parameter that characterizes the stress−strain relationship of ATB in pavement design is not clearly provided. This paper presents a study in which the stress−strain relationship of differing base materials, including three ATBs, a mixture of reclaimed asphalt pavement and granular material, and a typical granular base material, is compared a...

Numerical modeling of inelastic structures at loading of steady state rolling

In order to gain a deeper knowledge of the interactions in the coupled tire-pavement-system, e.g. for the future design of durable pavement structures, the paper presents recent results of research in the field of theoretical-numerical asphalt pavement modeling at material and structural level, whereby the focus is on a realistic and numerically efficient computation of pavements under rolling tire load by using the finite element method based on an Arbitrary Lagrangian Eulerian (ALE) formulation. Inelastic material descriptions are included into the ALE frame efficiently by a recently developed unsplit history update procedure. New is also the implementation of a viscoelastic cohesive zone model into the ALE pavement formulation to describe the interaction of the single pavement layers. The viscoelastic cohesive zone model is further extended to account for the normal pressure dependent shear behavior of the bonding layer. Another novelty is that thermo-mechanical effects are taken into account by a coupling of the mechanical ALE pavement computation to a transient thermal computation of the pavement cross-section to obtain the varying temperature distributions of the pavement due to climatic impact. Then, each ALE pavement simulation considers the temperature dependent asphalt material model that includes elastic, viscous and plastic behavior at finite strains and the temperature dependent viscoelastic cohesive zone formulation. The temperature dependent material parameters of the asphalt layers and the interfacial layers are fitted to experimental data. Results of coupled tire-pavement computations are presented to demonstrate potential fields of application.

Development and calibration of shear-based rutting model for asphalt concrete layers

This study improves a shear-based rutting model for asphalt concrete (AC) layers and calibrates the model with field data. With dynamic modulus-based material parameters, the laboratory rutting prediction model was improved and determined by the wheel tracking test and full-scale accelerated pavement test. Through the field survey on several in-service pavements, the rutting model was calibrated to be applied to AC layers. In the improved rutting prediction model, the ratio of maximum shear stress to shear strength was introduced to combine asphalt material design and pavement structural design. The speed correction coefficient and the new temperature processing method improve the accuracy of the rutting model. The calibrated rutting prediction model proves to be reasonable and accurate in predicting the rutting depth of AC layers.

Cambios en las propiedades dinámicas de una mezcla asfáltica por energía de compactación y variación en la granulometría

El objetivo de esta investigación es establecer la influencia en las propiedades dinámicas de unas mezclas asfálticas por cambios en su energía de compactación y su granulometría. Para el desarrollo de la investigación se utilizaron dos tipos de mezcla asfálticas, una mezcla cerrada (0/10) y mezcla abierta (0/20) y la variación de la energía de compactación se realizo mediante cambios en los golpes por cada cara de las briquetas en su proceso de fabricación. La investigación inició con la caracterización de los materiales granulares y el asfalto. Posteriormente se les realizó el ensayo marshall a las mezclas para determinar el porcentaje óptimo de asfalto, el cual se obtuvo de las gráficas de estabilidad, flujo y peso unitario. Finalmente, se realizaron ensayos de módulos dinámicos y ahuellamiento, para poder concluir cual es la energía de compactación óptima que debe tener la mezcla asfáltica, y así, optimizar el diseño y funcionamiento de estructuras de pavimentos flexibles con diferentes tipos de granulometría. Dentro de los resultados se resalta que el mayor módulo dinámico para la mezcla cerrada (0/10) se obtuvo para una energía de compactación de 85 golpes y para la mezcla abierta (0/20) de 75 golpes. Con respecto a la deformación permanente se obtuvo las menores deformaciones para la energía de compactación de 90 golpes en la mezcla cerrada y de 85 golpes para la granulometría abierta.

Impact of asphalt concrete fatigue endurance limit definition on pavement performance prediction

Many well-constructed Hot Mix Asphalt pavements have been in service for 40 or more years without any evidence of fatigue cracking. This field experience suggests that there exists a strain level, known as the fatigue endurance limit (FEL), below which an asphalt concrete pavement will not exhibit fatigue cracks. Several studies have been conducted to define and verify this limit. Each of these methods is associated with certain assumptions regarding the nature of the FEL and heretofore a comprehensive comparison of each has not been made using a consistent set of mixtures. Likewise, the impact of any observed differences in FEL on the predicted pavement performance has not been made. This paper investigates and compares six different methods for identifying the FEL: NCHRP 9–44A approach, simplified viscoelastic continuum damage model, smeared-healing with continuum damage model, plateau value approach, pseudo-strain analysis method, and reduced cycles method. Each method is found to yield different values ranges from approximately 30–170 microstrains at 21.1 °C. The predicted FEL from each of the six methods are then used with the mechanistic empirical design algorithm to evaluate their effects on predicted pavement performance. Simulation outputs show different pavement performance and perpetual pavement structural design thicknesses from each of the methods. The study outcomes are expected to benefit future field verification research of FEL as it provides comprehensive analyses using six different methods. This future verification research may indicate the method that best represents actual perpetual pavement design and performance.

Determination of Vehicles Load Equivalency Factors for Polish Catalogue of Typical Flexible and Semi-rigid Pavement Structures

The new Polish Catalog of Typical Flexible and Semi-rigid Pavement Structures was introduced to use in practice in 2014. Much of works were focused on actualization of vehicles load equivalency factors. For this purpose data delivered from weigh-in-motion were analyzed. Four methods of determination of load equivalency factors for pavement structure design were compared. The analysis showed that fourth power equation, AASHTO, 1993 and French LCPC methods derived load equivalency factors at similar level and these obtained factors can be underestimated in comparison to results delivered from mechanistic-empirical method. The paper presents a new approach to determine load equivalency factors with consideration of several issues which have a significant impact on traffic load assessment for pavement design. The weigh-in-motion data are available only for a small part of whole road network, thus to determine values valid for roads in whole country, the statistical analysis of load equivalency factor were performed. The dynamic coefficient can have significant impact on load equivalency factor, especially on minor roads with weak roughness of pavement surface. The weigh-in-motion derives archival data and it is known from long-term observations that vehicles weights and axle loads increase while pavement life period. Legal axle load limit and the percentage of overloaded vehicles have significantly impact on load equivalency factors. The final values of vehicle load equivalency factor were adjusted to include the coefficient of vehicle dynamic loads, growth of vehicle weights in the future and impact of overloaded vehicles.

Investigation causes of pavement structure destruction using new AASHTO mechanistic-empirical procedures for improving roads function in different climatic condition of Iran

In recent years, procedure of AASHTO (American Association State Highway and Transportation Officials) Guide for Design of Pavement Structures distanced from first empirical procedure and advanced toward mechanistic-empirical procedures. “Guide for Mechanistic-Empirical Design of New and Rehabilitated Pavement Structures” in 2004 and its attached software M-EPDG is the result of this new procedure that AASHTO presented it through projects NCHRP 1-37 A and NCHRP 1-40 B with cooperation of NCHRP (National Cooperative Highway Research Program) and FHWA (Federal Highway Administration) institutions. In this paper, required data for software analyzing of three real pavement structures pieces collected from three different climatic areas and pavement structures modeled in software by entering data into software. Modeled sections by this software were analyzed destructions, and, regarding to obtained results, common designing pavement structures procedures compared with the new way of AASHTO, and efficiency rate of related software investigated in three different climatic areas of Iran. Toward this process, Save, Hamadan and Qazvin, Boin Zahra cities selected as a case study and then studied. Results of software analyzing showed that the designs of old AASHTO method in tempered climate of country met all criteria of designing but in both of cold and warm areas, some destructions at designed pavement structures via this method exceeded from allowed rate and according to presented destructions, will be excessed more in future. This destruction in case project of cold area was longitude crack and was furrowing of pavement structures bed in warm area. Then, probable causes of mentioned destructions studied in pavement structures projects and procedures designed for rehabilitating pavement structures for met all of the designated criteria. Also, in Iran some suggestions indicated about required conductions for application of new method of AASHTO.

Investigation causes of pavement structure failure using new AASHTO mechanistic-empirical procedures for optimization roads performance in different climatic condition of Iran

Abstract
 In recent years, procedure of AASHTO (American Association State Highway and Transportation Officials) Guide for Design of Pavement Structures distanced from first empirical procedure and advanced toward mechanistic-empirical procedures. “Guide for Mechanistic-Empirical Design of New and Rehabilitated Pavement Structures” in 2004 and its attached software M-EPDG is the result of this new procedure that AASHTO presented it through projects NCHRP 1-37 A and NCHRP 1-40 B with cooperation of NCHRP (National Cooperative Highway Research Program) and FHWA (Federal Highway Administration) institutions. In this paper, requireddata for software analyzing of three real pavement structures pieces collected from three different climatic areas and pavement structures modeled in software by entering data into software. Modeled sections by this software were analyzed failure, and, regarding to obtained results, common designing pavement structures procedures compared with the new way of AASHTO, and efficiency rate of related software investigated in two different climatic zone of Iran. Toward this process, Save- Hamadan and Qazvin- Boin Zahra cities selected as a case study and then studied. Results of software analyzing showed that the designs of old AASHTO method in tempered climate of country met all criteria of designing but in both of cold and warm areas, some failure at designed pavement structures via this method exceeded from allowed rate and according to presented failure, will be excessed more in future. This destruction in case project of cold area was longitude crack and was rutting of pavement structures subgrade in warm area. Then, probable causes of mentioned failures studied in pavement structures projects and procedures designed for rehabilitation pavement structures for met all of the designated criteria. Also, in Iran some suggestions indicated about required conductions for application of new method of AASHTO.

Structural Design of Asphalt Pavements: Principles and Practices in Various Design Guidelines

Procedures to perform structural design of pavements are detailed in various design guidelines. Even though the recommendations may be different across the different guidelines, some of the underlying principles are similar. The present paper briefly reviews various pavement design guidelines on structural design of asphalt pavements with reference to the design principles employed. The focus is primarily kept on the mechanistic–empirical pavement design approach. The discussion covers few specific aspects of asphalt pavement design, and does not intend to present an exhaustive treatise on the subject.

ROAD SUBGRADE STRENGTH UNDER VARIOUS FLOODING EVENT

Flooding and water inundation could result in great damage to road pavements. In principle, the design of pavement structure is based on the strength of compacted soil known as subgrade or road foundation. Therefore, subgrade is the major significant part of road structural systems. When roads are inundated for a long time or repeatedly, the materials in each layer of road structure become saturated, and then the original condition of subgrade soils will be compromised. This study investigated the effect on sub-grade strength and properties due to road submergence period and repeated submergence of road structural systems. Two types of soil that are normally used as the embankment soils in road construction, which can be categorized as cohesive and cohesionless materials were used in this study. California Bearing Ratio (CBR) test and Oedometer consolidation test were carried out on the various categories of inundation and loading conditions including repeated inundation. The findings indicated that the strength of subgrade materials were affected differently depending of inundation period and number of repeated inundation.

Laboratory characterization of cementitiously treated/stabilized very weak subgrade soil under cyclic loading

This research study was performed to examine the appropriate treatment/stabilization schemes for very weak subgrade soils at high water contents, and to evaluate the corresponding performance-related properties [e.g., resilient modulus and permanent deformation] for use in the design and analysis of pavement structures. Five different soil types, that represent the typical range in subgrade soils in Louisiana, were collected and considered in this study. Three different moisture contents (at the wet side of optimum), producing a raw soil strength of 172kPa (25psi) or less, were selected for treatment/stabilization. The percentage of cementitious stabilizer (lime or cement) was determined to achieve a target 7-day strength value of 345kPa (50psi), as treatment for working table applications, and 1034kPa (150psi), as stabilization for subbase applications. Repeated load triaxial (RLT) tests were performed on the laboratory-molded treated/stabilized specimens in order to evaluate their resilient modulus and to study their deformation behavior under cyclic loading. A good correlation was observed between the water/cement ratio and both the resilient modulus and the permanent deformation of the specimens. The soil specimens were compacted at low water/cement ratios and showed better performances than those compacted at high water/cement ratios. The test results also showed that the use of a direct correlation between the unconfined compressive strength (UCS) and the resilient modulus for cementitiously stabilized soil can be misleading. In the case of heavily treated/stabilized subgrade soils for subbase applications, the permanent deformation of this layer can be ignored in pavement design.

Holistic Analysis of the Coupled Vehicle-Tire-Pavement System for the Design of Durable Pavements

ABSTRACT Pavements—an important part of worldwide infrastructure—are exposed to increasing traffic loads, new tire and vehicle concepts, and climate change. The future design of durable pavement structures requires a deep knowledge of the interactions in the coupled system of vehicle, tire, and pavement and the structural behavior of each subsystem. This paper includes recent research results in the field of tire and pavement modeling and their interaction. Furthermore, the concept for a holistic analysis of the coupled vehicle-tire-pavement system for the design of durable pavements is presented. For a realistic and numerical efficient computation of tire-pavement interaction that considers rolling contact, both subsystems are modeled using the finite element (FE) method based on an arbitrary Lagrangian Eulerian (ALE) formulation that includes inelastic material descriptions. Additionally, thermo-mechanical effects are considered for the tire computation. The base of the structural FE-ALE pavement model is the realistic numerical description of the elastic, viscous, and plastic behavior of asphalt mixes. Although initial results in the field of tire-pavement interaction were reached, much research has to be carried out to gain deeper knowledge of the coupled vehicle-tire-pavement system that includes detailed models of the subsystems and their interaction, as well as experimental investigations. The research group FOR 2089 will deal with this topic and will take the different length and timescales in particular into account.

Utilization of Construction and Demolition Wastes in Low-Volume Roads for Rural Areas in China

This paper presents a study in which the engineering properties of recycled construction and demolition wastes were evaluated for application to the construction of low-volume roads in rural areas of China. Crushed clay brick and waste concrete, two types of commonly available construction and demolition wastes, were selected. Scanning electron microscopy was used to characterize the influence of the hydration process on microstructure. Properties, including moisture–density relationships and unconfined compression strength, were evaluated. A field application of the use of construction and demolition wastes in low-volume roads was also presented. The study results indicate that construction and demolition wastes may be successfully used as a cement-stabilized base in constructing rural low-volume roads. The results of laboratory and field investigations from the study also provided reference for future mix design and pavement structural design, as well as construction quality control and quality assurance for similar applications in the future.