Showing papers in "International Journal of Pavement Engineering in 2008"
TL;DR: The detrimental effects of water in asphalt mixtures and its manifestation as distresses in asphalt pavements were first recognised in the 1930s and have been studied extensively during the last 35 years as mentioned in this paper.
Abstract: The detrimental effects of water in asphalt mixtures and its manifestation as distresses in asphalt pavements were first recognised in the 1930s and have been studied extensively during the last 35 years. This deterioration process, referred to as moisture damage, is generally defined as the degradation of the mechanical properties of the material due to the presence of moisture in its microstructure. Moisture damage is a complex phenomenon that involves thermodynamic, chemical, physical and mechanical processes. This paper describes the processes by which moisture damage affects asphalt mixtures. A critique of various moisture damage mechanisms is presented, followed by a review of recent work on modes of moisture transport (i.e. water permeability, capillary rise and vapour diffusion) and their relationship to moisture damage. Special attention is given to the characterisation of void structures of asphalt mixtures, which is an important factor that influences moisture transport. Finally, the paper pres...
330 citations
TL;DR: In this article, a method to characterize fatigue resistance of the fine portion of the asphalt mixture using the dynamic mechanical analyzer (DMA) was presented, and three mixtures were characterized in controlled-strain and controlled-stress modes of loading.
Abstract: Fatigue cracking is one of the primary distresses in asphalt pavements. This study presents a method to characterize fatigue resistance of the fine portion of the asphalt mixture using the dynamic mechanical analyzer (DMA). Three mixtures were characterized in controlled-strain and controlled-stress modes of loading. The new method has several advantages as it requires reasonable testing time, uses a small amount of material, utilizes fundamental properties of the mixture, and is able to unify the results from controlled-strain and controlled-stress modes of loading. The unified method relies on identifying the different mechanisms of energy dissipation during fatigue cracking that are related to changes in the phase angle, changes in stiffness, and development of permanent deformation during the fatigue damage process. Two fatigue damage parameters are derived in this paper. The parameters are shown to have reasonable and lower coefficients of variation than conventional parameters such as number of load...
127 citations
TL;DR: In this article, the authors discuss existing tests and analytical methods that can be used to assess and quantify moisture damage potential in asphalt mixtures and present a new approach for classifying moisture damage, which emphasises recent analytical developments.
Abstract: Moisture damage in asphalt pavements is the degradation of the mechanical properties of the asphalt composite due to the action of water. In a companion paper the mechanisms of moisture damage were discussed. It was established that in order to characterise moisture damage in asphalt mixtures, it is important to comprehensively describe and model the effect of thermodynamic, chemical, physical, and mechanical processes. This paper discusses existing tests and analytical methods that can be used to assess and quantify moisture damage potential in asphalt mixtures. These methods range from visual qualification of asphalt binder stripped from the aggregate, to analytical-based models that include multiple material properties derived using fracture mechanics, continuum mechanics, thermodynamics, and/or micromechanics. In addition, this paper presents a new approach for classifying moisture damage, which emphasises recent analytical developments. Finally, advances in the mathematical modelling of moisture dama...
93 citations
TL;DR: In this paper, a comprehensive energy-based framework is proposed to model the failure pattern occurring in an asphaltic pavement under the given environmental and traffic loading which could be rutting, cracking, ravelling or any combination or manifestation thereof.
Abstract: Moisture has for a long time been recognised as a serious contributor to premature degradation of asphaltic pavements. Many studies have been performed to collect, describe and measure the moisture susceptibility of asphaltic mixes. Most of these are aimed at a comparative measure of moisture damage, either via visual observations from field data or laboratory tests or via mechanical tests, which give a so called moisture damage index parameter. The research presented in this paper is part of an ongoing effort at Delft University of Technology, to move away from such comparative or empirical measures of moisture-induced damage and start treating moisture-induced damage in a comprehensive energy based framework. Such a framework would enable realistic predictions and time-assessment of the failure pattern occurring in an asphaltic pavement under the given environmental and traffic loading which could be rutting, cracking, ravelling or any combination or manifestation thereof. The modelling of moisture-indu...
85 citations
TL;DR: In this article, the authors developed an energy-based computational framework which incorporates moisture-induced damage by integrating the physical and mechanical moistureinduced damage processes within the (dry) elasto-visco-plastic constitutive model.
Abstract: Moisture-induced damage in asphaltic mixes is a complex problem which needs to be approached ‘from the inside out’. It is of essence to determine the fundamental physical and mechanical processes which contribute to moisture-induced damage. Once these processes are determined, the controlling parameters need to be defined and measured. The research described in this and the previous paper is focusing on the development of an energy-based computational framework which incorporates moisture-induced damage by integrating the physical and mechanical moisture-induced damage processes within the (dry) elasto-visco-plastic constitutive model. In the previous paper, the moisture infiltration processes and their formulations were derived and verified. In this paper, focus is placed on the determination of the moisture susceptibility parameters of the computational model. Determination of moisture diffusion coefficients of the mastic is discussed and a computational study is performed to show the effect of filler c...
80 citations
TL;DR: In this paper, the reliability issues in bituminous pavement design, based on mechanistic-empirical approach, have been discussed and a methodology has been suggested for designing a pavement for a given level of overall reliability by mechanistic and empirical pavement design approach.
Abstract: The reliability issues in bituminous pavement design, based on mechanistic–empirical approach, have been discussed in this paper. Variabilities of pavement design input parameters are considered and reliability, for various proposed failure definitions, of a given pavement is estimated by simulation as well as by analytical (first order second moment) method. A methodology has been suggested for designing a bituminous pavement for a given level of overall reliability by mechanistic–empirical pavement design approach.
61 citations
TL;DR: In this paper, the authors identify mechanical and physical properties of geogrids that are critical to their effectiveness in the stabilisation of pavement subgrade, including aperture size, wide-width tensile strength and junction strength.
Abstract: This study attempts to identify mechanical and physical properties of geogrids that are critical to their effectiveness in the stabilisation of pavement subgrade. Geogrid properties, including aperture size, wide-width tensile strength and junction strength, for four geogrid products are correlated with bench-scale interface test results, including direct shear and pull-out, and accelerated pavement testing (APT) results. APT is conducted through the use of a one-third scale APT device, the model mobile load simulator (MMLS3) on geogrid-reinforced pavement sections. The pavement sections are constructed on a subgrade soil with a low California bearing ratio. The performance of each pavement section is evaluated by measuring surface rutting at various trafficking stages. The analysis reveals a strong relationship between performance and junction and tensile strength of geogrids at small strains, whereas aperture size has a positive correlation with pull-out test results.
60 citations
TL;DR: In this article, a neural network-based asphalt compaction analyzer capable of predicting the density continuously, in real time, during the construction of the pavement is presented, which is verified using laboratory data from an asphalt vibratory compactor (AVC).
Abstract: Achieving the desired density during field compaction of asphalt mixes is critical to meeting the design specifications of an asphalt pavement. Existing techniques measure the density of asphalt mixes at a discrete number of points. As such, the process is cumbersome, time consuming, and is not indicative of the overall compaction achieved unless large amounts of data is collected and analyzed. In this paper, the concept of a novel neural network-based asphalt compaction analyzer capable of predicting the density continuously, in real time, during the construction of the pavement is presented. The concept is verified using laboratory data from an asphalt vibratory compactor (AVC). The compaction analyzer is based on the hypothesis that a vibratory compactor and the hot mix asphalt (HMA) mat form a coupled system having unique vibration properties. The measured vibrations of the compactor along with the process parameters such as lift thickness, mix type, mix temperature, and compaction pressure can be use...
53 citations
TL;DR: In this paper, the authors presented the prediction equations to estimate the Resilient Modulus (M R) of subgrade soils from a set of soil physical properties for the unified soil classification system soil types.
Abstract: Resilient modulus (M R) of subgrade soils is the elastic modulus based on the recoverable strain under repeated loads and depends on several factors such as soil properties, soil type and stress states. This paper presents the prediction equations to estimate M R from a set of soil physical properties for the unified soil classification system soil types namely coarse-grained and fine-grained subgrade soils. Data extracted from long-term pavement performance information management system database for 259 test specimens of reconstituted soil samples from 19 states in New England and nearby regions in the USA and two provinces in Canada were used in this study. Generalised constitutive model consisting bulk stress and octahedral shear stress was used to predict the M R of subgrade soils by developing equations for the regression coefficients (k-coefficients) in the constitutive model that relates them to various soil properties. Prediction models were developed by conducting multiple linear regression analy...
51 citations
TL;DR: In this article, the authors evaluate the relationship between the performance of asphalt pavements in the field and the TSR values measured in laboratory on the original asphalt mixtures used in constructing pavements, and evaluate the effect of anti-stripping additives on field performance.
Abstract: The Wisconsin Department of Transportation (WisDOT) has been using the tensile strength ratio (TSR) test (ASTM D-4867) to predict the potential susceptibility of asphalt mixture to moisture damage and other associated pavement deterioration. The objectives of this paper are to evaluate the relationship between the performance of asphalt pavements in the field and the TSR values measured in laboratory on the original asphalt mixtures used in constructing pavements, and to evaluate the effect of anti-stripping additives on field performance. To assess the moisture damage problem in the field, 21 existing WisDOT pavement sections that were built prior to the adoption of the TSR parameter as a requirement, were selected to cover a wide range of locations and aggregate sources. The TSR and the pavement performance data (pavement distress index or PDI) for these projects were collected from the WisDOT pavement management database. The results indicated no relationship between TSR and field pavement performance ...
48 citations
TL;DR: In this article, the authors used a three-dimensional discrete element model to simulate the resilient response of an unbound granular material subjected to sinusoidal loading in a triaxial sample and compared the simulated results to experimental results.
Abstract: The scope of this study is to use a three-dimensional discrete element model to simulate the resilient response of an unbound granular material subjected to sinusoidal loading in a triaxial sample and to compare the simulated results to experimental results. A three-dimensional discrete element model, where each grain interacts with its neighbour grains, allows a micromechanical approach to modelling. By doing the sensitivity analysis on the input parameters the model can be evaluated and insight gained about the factors that affect the resilient behaviour. Uniform spherical grains were used in both the DEM simulations and in the triaxial experiments. Two contact models, linear visco-elastic and Hertzian, and two types of confinement, a uniform cylinder and a flexible membrane, are tested in the simulations. Comparison of the simulation results with the results of similar laboratory experiments shows that the discrete element approach is suitable to model idealised aggregate grains.
TL;DR: In this article, the authors explored the possibility of using fractional creep functions for modelling the time-dependent deformation behavior of bituminous material in terms of the retarded creep during loading and the relaxation behaviour during unloading.
Abstract: Traditionally, the time-dependent behaviour of bituminous mixtures has been modelled using linear visco-elastic theory described by creep and relaxation functions. Research, however, has shown that parameter identification for functions with linear time derivatives becomes problematic when the behaviour of asphalt mixtures needs to be matched for both the loading and unloading responses. The research introduced in this paper explored the possibility of using fractional creep functions for modelling. Furthermore, the possibility of using fractional creep functions for various rheological bodies to investigate the fractional time derivatives for strain is discussed. It is shown that, by means of these creep functions, the time-dependent deformation behaviour of bituminous material in terms of the retarded creep during loading and the relaxation behaviour during unloading may be described more realistically than by using time derivatives of integer order. The fractional creep functions allow for the developm...
TL;DR: In this paper, the effects of unbound aggregate base residual stresses on the resilient response behavior of geogrid reinforced flexible pavements were investigated using a finite element (FE) based mechanistic response model.
Abstract: This paper presents findings of an analytical study aimed at investigating the effects of unbound aggregate base residual stresses on the resilient response behaviour of geogrid reinforced flexible pavements A finite element (FE) based mechanistic response model recently developed at the University of Illinois was used to predict critical pavement responses of unreinforced and geogrid reinforced flexible pavements The nonlinear analyses performed in the base and subgrade also considered different horizontal compressive residual stress distributions introduced as locked-in initial stresses in the base course due to pavement construction and subsequent repeated traffic loading The primary focus was to study effects of increased confinement and stiffening around geogrid on improved granular layer moduli and reduced critical subgrade vertical strains/stresses by assigning initial residual stresses around the geogrid tensile reinforcement in the FE pavement continuum analysis An increase in horizontal conf
TL;DR: In this article, an alternative roughness index is developed taking into account the above parameters, which seems to have an advantage over the International Roughness Index (IRI) and the power spectral density (PSD) spectrum that is often applied for evaluating pavement roughness.
Abstract: Although structural capacity seems to be the major concern of many pavement engineers, road users primarily judge the quality of a road based on its roughness or ride quality. Several parameters influence the ride quality of pavements as felt by the road users. These parameters include pavement surface characteristics, as well vehicle characteristics such as vehicle response and speed. In the present study these parameters contribute to the pavement roughness evaluation by using proper mathematical models accomplished with field data analysis information. Furthermore, an alternative roughness index is developed taking into account the above parameters. The suggested index seems to have an advantage over the international roughness index (IRI) and the power spectral density (PSD) spectrum that is often applied for evaluating pavement roughness.
TL;DR: In this paper, the authors present the results of a laboratory investigation on the effect of gradation on frost susceptibility, quantified with the segregation potential (SP), of three aggregate sources.
Abstract: Base granular materials are generally considered non-frost susceptible, which is an adequate assumption based on widely recognised frost criterions. However, their frost susceptibility is influenced by the presence of water that can unavoidably penetrate pavement structures. Even if unsaturated, freezing of unbound granular materials causes a net volume gain and an increase in water content which affect pavement performance during the spring period. This paper presents the results of a laboratory investigation on the effect of gradation on frost susceptibility, quantified with the segregation potential (SP), of three aggregate sources. The results suggest that SP values for all sources are strongly related to a fine particles state parameter. Moreover, the source influence was found to be described adequately with a parameter describing fine particles grain size distribution uniformity and fines specific surface. A model is proposed which combines gradation and mineralogical source effects on frost suscep...
TL;DR: In this paper, the use of monotonic and cyclic load indirect diametrical tensile (IDT) testing to determine the stiffness characteristics of light stabilised granular materials with cementitious binders is examined.
Abstract: Lightly stabilised granular materials with cementitious binders are generally characterised by their stiffness modulus and this paper examines the use of monotonic and cyclic load indirect diametrical tensile (IDT) testing to determine the stiffness characteristics of these materials. The experimental programme included the determination of density, IDT strength and static and dynamic moduli from monotonic and cyclic load IDT testing for a typical freshly quarried aggregate granular base material stabilised by the addition of 3–5% slag–lime slow-setting binder under a narrow range of moisture variations. The IDT tests were conducted on 28 days cured samples prepared by gyratory compaction. Details of an IDT testing arrangement with internal displacement measurement for performing cyclic load testing to obtain reliable data are also discussed. This study indicates that cyclic load IDT testing could be used reliably for determining the dynamic stiffness modulus of a lightly stabilised granular material with...
TL;DR: In this article, the authors discuss the underlying assumptions of ordinary least square regression analysis and show that these assumptions are violated while developing fatigue/rutting equations from the data obtained from field or laboratory measurements.
Abstract: Fatigue and rutting equations are essentially used in design of asphalt pavements by mechanistic-empirical method and they are developed from the laboratory and/or the field performance data. Conventionally, ordinary least square regression analysis is employed for developing these equations. The present paper discusses the underlying assumptions of ordinary least square regression analysis and shows that these assumptions are violated while developing fatigue/rutting equations from the data obtained from field or laboratory measurements. This paper proposes the use of a measurement error based estimator in order to alleviate the inaccuracy associated with use of least square regression analysis while developing fatigue and rutting equations. A step-by-step methodology is presented on how to develop the fatigue or rutting equation from a given data set using the proposed method. The confidence intervals of the estimators are obtained using bootstraping technique. Finally, a design example is presented to ...
TL;DR: In this paper, the authors investigated the effect of free mica particles in unbound granular materials used in road construction, and found that they can detrimentally influence bearing capacity.
Abstract: Elevated amounts of free mica particles in unbound granular materials used in road construction are believed to detrimentally influence bearing capacity. The objective of presented work was to inve ...
TL;DR: The non-recovered compliance can be obtained in two ways using two different types of tests in the dynamic shear rheometer as mentioned in this paper : frequency, time, strain or stress sweep, wherein the data generated is in terms of the complex modulus and phase angle that can be used in a proper mathematical form to obtain the non-recovery compliance.
Abstract: Nonrecovered compliance is presently being viewed as the most appropriate rheological parameter for evaluating the propensity of an asphalt binder to resist permanent deformation or rutting in the pavement wheel paths. The nonrecovered compliance can be obtained in two ways using two different types of tests in the dynamic shear rheometer. One is through the dynamic oscillatory test using a frequency, time, strain or stress sweep, wherein the data generated is in terms of the complex modulus and phase angle that can be used in a proper mathematical form to obtain the nonrecovered compliance. The other is through the multiple stress creep and recovery test wherein the nonrecovered strain at each stress level after 10 cycles of creep and recovery is divided by the stress value to obtain the nonrecovered compliance. The two methods are very different in the way data gets generated and handled and, also, in the level of ease or difficulty in data generation. With two methods competing to come up with the same...
TL;DR: In this paper, the effect of compaction effort, curing time, aggregate gradation and choice of additive on the performance of the cold mixes was investigated and a structural evaluation of a cold-in-place recycled layer was carried out using falling weight deflectometer.
Abstract: Cold-in-place recycling (CIR) is a popular and cost-effective bituminous pavement rehabilitation technique. India has very limited experience with this technique. A few stretches of national highways were rehabilitated in the recent past using CIR technique. In the present investigation, laboratory experiments were conducted on different cold-recycled mixes prepared using the bituminous material milled from in-service bituminous pavement. The effect of compaction effort, curing time, aggregate gradation and choice of additive on the performance of the cold mixes was investigated. Structural evaluation of a cold-in-place recycled layer was carried out using falling weight deflectometer. Laboratory investigation yielded guidelines on appropriate accelerated curing conditions, compaction effort and optimum fluid content to be adopted for the preparing cold-recycled mixes using the milled bituminous material obtained from typical Indian highways. Structural evaluation of the recycled layer suggested significa...
TL;DR: In this paper, the authors investigated the procedures and methods of establishing thresholds and developing performance prediction models for asphalt concrete overlays, and two stage survival models were proposed to predict the resurfacing cycles.
Abstract: Asphalt concrete (AC) resurfacing is used by highway agencies to maintain and improve existing pavement conditions. With a large portion of their budgets being spent on road maintenance and rehabilitation, the agencies are interested in identifying the optimal timing of resurfacing and its life expectations. Using Kentucky's pavement management data, the research as presented by this paper investigated the procedures and methods of establishing thresholds and developing performance prediction models for AC overlays. Both transition probability matrix and data plots were used to investigate the performance trend of overlays. Based on the trend, two stage survival models were proposed to predict the resurfacing cycles. The first stage model can be used to predict the useful life of an overlay before a new resurfacing is required, while the second one can be used to predict the time window during which the new overlay must be applied to avoid accelerated pavement deterioration.
TL;DR: In this paper, the authors explored whether marginal materials like lightweight volcanic aggregates (LVA) could economically and effectively be stabilised using natural pozzolan so as to conform to roadbase specifications.
Abstract: The aim of this study was to explore whether marginal materials like lightweight volcanic aggregates (LVA) could economically and effectively be stabilised using natural pozzolan so as to conform to roadbase specifications. The combinations of natural pozzolan with lime; natural pozzolan with natural activator (natural gypsum); and natural pozzolan, lime and natural activator mixes were examined for their binding capabilities. Three types of natural pozzolan and two types of LVA materials from Arusha region in Tanzania were studied. Standard tests on physical, chemical and mineralogical properties of both the virgin materials and the stabilised mixes were carried out. Laboratory test results and statistical analyses show that natural pozzolan–lime binder could stabilise LVA to achieve roadbase strength requirements at a dosage of less than 2% of lime with between 10 and 30% (by mass) of natural pozzolan. Natural pozzolan–gypsum–lime binder mixes were found to develop a significantly higher unconfined comp...
TL;DR: In this paper, a simulation tool for the compaction process of hot mix asphalt (HMA) using a roller under varying external conditions is presented, where principal stresses, strains and shear stresses inside the material during rolling, and the incremental displacements of the material.
Abstract: This paper introduces a simulation tool for the compaction process of hot mix asphalt (HMA) using a roller under varying external conditions. The focus is on the use of the finite element model (FEM) with code DiekA, on its necessary requirements and on the presentation of simulation results. The approach requires the availability of a suitable material model, equipment to measure material parameters and a laboratory-testing program for fitting the correct material parameters. Subsequently, in discussing the simulation results attention is paid to; the principal stresses, strains and shear stresses inside the material during rolling, and the incremental displacements of the material. Furthermore, the simulated density path as a function of depth inside the layer is presented for a series of applied roller passes. In conclusion it can be stated that FEM approaches in general are well suited to simulate compaction processes of HMA on condition that the selected FEM comprises the right features.
Journal Article•
TL;DR: In this paper, a comparison of the merits and demerits of the two methods in order to ascertain which one is more reliable, more fundamental, easier to use and better to implement is presented.
Abstract: Nonrecovered compliance is presently being viewed as the most appropriate rheological parameter for evaluating the propensity of an asphalt binder to resist permanent deformation or rutting in the pavement wheel paths. The nonrecovered compliance can be obtained in two ways using two different types of tests in the dynamic shear rheometer. One is through the dynamic oscillatory test using a frequency, time, strain or stress sweep, wherein the data generated is in terms of the complex modulus and phase angle that can be used in a proper mathematical form to obtain the nonrecovered compliance. The other is through the multiple stress creep and recovery test wherein the nonrecovered strain at each stress level after 10 cycles of creep and recovery is divided by the stress value to obtain the nonrecovered compliance. The two methods are very different in the way data gets generated and handled and, also, in the level of ease or difficulty in data generation. With two methods competing to come up with the same outcome, it is important to see a comparison of the merits and demerits of each of the methods in order to ascertain which of the two is more reliable, more fundamental, easier to use and better to implement. The purpose of this paper is to provide a one-on-one comparison between the two methods using the same set of binders and also to look at the possible benefits of one over the other.
TL;DR: In this paper, the authors describe the development of a mechanistic-empirical (M-E) thickness design system for HMA overlaid rubblized PCC pavements.
Abstract: In Iowa, there are many portland cement concrete (PCC) type highway pavements. These pavements deteriorate over time due to materials, traffic and environmental related distresses and they are commonly rehabilitated by providing a hot-mix asphalt (HMA) overlay. To mitigate reflection cracking, a frequently observed distress on HMA overlaid PCC pavements, various fractured slab techniques are used, of which rubblization is considered to be the most utilized and effective technique. This paper describes the development of a mechanistic–empirical (M–E) thickness design system for HMA overlaid rubblized PCC pavements. In this computerized design procedure, HMA fatigue and subgrade rutting failure are considered using appropriate transfer functions. The design system strain predictions were validated using field results from an instrumented trial section in Polk county, Iowa.
TL;DR: In this paper, the aging of two bituminous sealants in large kettles during field applications was compared to that obtained in the laboratory by heating in a small kettle, and the results indicated that 4h of small kettle aging at the highest suggested sealant application temperature (HiSAT), or about 2h at HiSAT+10°C, provided as much copolymer aging as that found in sealants sampled midway through installation.
Abstract: Bituminous sealants used in the maintenance of roadways are installed hot and heated to 150–200°C during installation. High temperatures can degrade polymers in sealants, but there is no standard method to account for this possible degradation. In an attempt to find such a method, the aging of two sealants in large kettles during field applications was compared to that obtained in the laboratory by heating in a small kettle. The results indicate that 4 h of small kettle aging at the highest suggested sealant application temperature (HiSAT), or about 2 h at HiSAT + 10°C, provided as much copolymer aging as that found in sealants sampled midway through installation.
TL;DR: In this paper, an alternative explanation based upon a gradual growth of upward thermal buckles, induced by the cyclical changes of membrane stresses that accompany the constrained inplane expansion and contraction, resulting from fluctuations in surface temperature.
Abstract: Asphalt layers used to provide smooth, compliant, surfaces on pavements often experience the growth of small uplift blisters. Conventional wisdom has it that these blisters are the result of a build-up of either volatile gases or water vapour beneath the asphalt that accompanies a significant increase in surface temperature. This paper argues that in many cases such a cause is unlikely. It suggests an alternative explanation based upon a gradual growth of upward thermal buckles, induced by the cyclical changes of membrane stresses that accompany the constrained in-plane expansion and contraction, resulting from fluctuations in surface temperature. With asphalt displaying reduced elastic-visco-plastic stiffness at high temperatures a proportion of the growth in an upward buckle, occurring at elevated temperatures, will not be recovered when temperatures again drop. Over time a form of thermo-mechanical ratchet process appears to be set in motion, resulting in the gradual upward growth of these blisters. Re...
TL;DR: The first fully instrumented flexible pavement test section in Maine was constructed in Fall 2005 as discussed by the authors, where temperature data were analyzed to develop models to predict these temperatures on the basis of ambient temperature and solar radiation.
Abstract: The first fully instrumented flexible pavement test section in Maine was constructed in Fall, 2005. Temperature data were collected for a period of 5 months and stress–strain data were collected by running a truck at different speeds. The temperature data were analysed to develop models to predict these temperatures on the basis of ambient temperature and solar radiation. The haversine equation was found to be suitable for modelling the strain response in HMA layers, whereas slight variations were used for modelling the responses in the subbase and subgrade layers. The strain in the HMA layer shows a lag when compared to the fitted model. The HMA tensile strains matched well with the predicted strains at lower time of loading and lower temperatures. Subbase stresses were greater than predicted values. The subbase strains matched well with the predicted ones. The measured subgrade stresses were greater than predicted stress values.
TL;DR: In this article, the influence of moving loads on pavement analysis, namely their characteristics and time distribution, is illustrated. And a state-of-the-art load model for pavement analysis is presented.
Abstract: This paper aims to illustrate the influence of moving loads on pavement analysis, namely their characteristics and time distribution. Firstly, a state-of-the-art load model for pavement analysis is presented. Components of traffic load (contact stresses), their magnitude and time distribution, the tyre-pavement contact area and the characterization of a moving load according to dynamic and static formulations are introduced. Secondly, a study of the influence of load models (uniform vs. non-uniform distribution and non-moving vs. moving load) for pavement analysis by modelling a flexible pavement with the finite element method (FEM) is performed. The structure is modelled with DIANA software (TNO 2005), considering bituminous layers as a viscoelastic material and granular layers and foundation as a linear elastic material. The study reaches the conclusion that pavement response presents different evolutions, during loading time, depending on whether we choose a uniform or non-uniform time distribution loa...
TL;DR: In this paper, a small-scale tracking test was developed and applied to 21 bituminous sealants held at temperatures between 46 and 82°C, typical pavement temperature maximums in North America.
Abstract: The bituminous sealants used in the maintenance of roadways sometimes fail because of the excessive deformation or flow under the shearing action of tires in summer temperatures. This issue has yet to be studied and no data on sealant deformation and flow are available. To address this issue, a small-scale tracking test was developed and applied to 21 sealants held at temperatures between 46 and 82°C, typical pavement temperature maximums in North America. It was found that sealant shear deformation increased linearly or non-linearly with temperature, and that past a temperature threshold, sealants deformed excessively and tracked. The tracking failure temperature was readily identified. Some sealants showed a tracking failure at fairly low temperatures, 46–64°C, but most only failed at 76°C or beyond. The sealant flow characteristics, acquired under pseudo-field conditions, provide the basis for developing a performance-based method to assist in the selection of sealants with resistance to tracking.