Mechanistic-Empirical Pavement Design Guide Analysis Research Articles

Effect of glass fiber on the properties of expansive soil and its utilization as subgrade reinforcement in pavement applications

The purpose of this study is to investigate the use of glass fibers as discrete random reinforcement in expansive subgrade soil to improve its strength for pavement application. The fiber content varied between 0.25 % and 1.0 % by weight of dry soil. A series of free swell, Unconfined Compressive Strength (UCS), Indirect Tensile Strength (ITS), and California Bearing Ratio (CBR) tests were conducted on unreinforced and reinforced expansive soil specimens. In addition, the effect of the inclusion of the fiber on the design and performance of flexible pavement was evaluated using the Mechanistic-Empirical Pavement Design Guide (MEPDG). The test results showed that the inclusion of glass fibers in subgrade soil significantly increases the UCS, ITS, and CBR, and decreases the free swell values. MEPDG analyses showed that the glass fibers could be a suitable reinforcement for the subgrade layer for pavement construction. A significant decrease in pavement thickness can be achieved by the inclusion of glass fibers in subgrade stabilization.

Effects of mean annual temperature and mean annual precipitation on the performance of flexible pavement using ME design

The purposes of this study were to establish the difference between empirical and mechanistic–empirical approaches in the flexible pavement design and to quantify the effects of mean annual precipitation and temperature on the flexible pavement distresses using the Mechanistic-Empirical Pavement Design Guide (MEPDG) software. Seventy-six specific locations from 13 states throughout the USA were selected based on different climate conditions using virtual climate stations based on the interpolation from the nearest weather stations prior to meeting the objectives. Subsequently, analysis was conducted based on the predicted distresses, including longitudinal cracking, transverse cracking, alligator cracking, asphalt concrete rutting and total pavement permanent deformation. Generally, the pavement structure and materials have been set as constant to control the effects of material on the results. On the basis of the MEPDG analysis, the longitudinal cracking of flexible pavement is significantly affected by both factors (temperature and precipitation), particularly in wet climatic regions. The mean annual temperature has a great influence on the alligator cracking, transverse cracking and permanent deformation of flexible pavement. However, neither factors demonstrated a significant impact on the predicted International Roughness Index of flexible pavement surfaces.

MEPDG Analysis on Relationship between Design Inputs and Performance of Asphalt Pavements

The main objective of this research is to explore the quantitative relationship between the pavement design parameters (structural layer thickness, voids, aggregate gradation and temperatures) and pavement performance parameters (rutting, cracking and IRI). The Mechanistic-Empirical Pavement Design Guide (MEPDG) was used and the analysis was performed on pavements under three temperature conditions namely the intermediate temperature zone (Zhengzhou in Henan Province), the low temperature zone (MOHE in Heilongjiang province) and the high temperature zone (Turpan in Xinjiang province). It was observed that 1) Pavement performances (rutting and cracking) were significantly impacted by layer thickness values until the values were larger than 14 inch; 2) Air void content influenced on not only predicted pavement rutting but also the thermal cracking.

Characterization of Overweight Permitted Truck Routes and Loads in Wisconsin

This study analyzed 95,000 overweight (OW) single-trip truck permits issued in Wisconsin between May 2007 and June 2013. A geographic information system and relational databases were used to conduct a statewide routing analysis to identify highways that are heavily used by OW permitted trucks, such as WI-140. Field studies at WI-140 confirmed a high proportion of OW trucks. In addition, pavement damage and deterioration caused by heavy truck traffic were investigated by conducting a visual distress survey and determination of the pavement condition index (PCI). The pavement of WI-140 was heavily distressed, with a PCI description of very poor. The Mechanistic–Empirical Pavement Design Guide (MEPDG) was used on WI-140 to evaluate the performance of the pavement under OW truck traffic. The results of the MEPDG analysis showed that the pavement was heavily distressed and deteriorated, a condition that was consistent with field measurements and observations. A primary application of the routing and pavement analyses is to assist the Wisconsin Department of Transportation in developing rehabilitation strategies for deteriorated pavements.

Evaluating the use of neural networks and genetic algorithms for prediction of subgrade resilient modulus

This paper investigates the use of artificial neural networks (ANNs) and genetic algorithms to improve the accuracy of the prediction of subgrade resilient modulus (M r) based on soil index properties. Furthermore, it also examines the effect of the accuracy of the M r estimation on the mechanistic empirical pavement design guide (MEPDG) performance prediction. The results of this paper showed that the ANN models had much better prediction of the M r coefficients of subgrade soils than that of the regression models. In addition, the use of the genetic algorithms in the selection of the input variables of the ANN models enhanced the accuracy of the prediction of those models. The results of the MEPDG analyses indicated that the prediction model used to estimate the subgrade M r input value can have a significant effect on the predicted performance of pavements. Furthermore, those results showed that the use of ANN models yielded much more accurate pavement performance prediction than using regression models; in particular when genetic algorithms were used in developing those models.

Performance Evaluation and Environmental Impact Assessment of Asphalt-Treated Mixtures Used in Low-Volume Roads

The performance of asphalt-treated mixtures used in low-volume roads was evaluated, and their environmental benefits were assessed. Laboratory tests, including permeability, modified Lottman, Hamburg-type loaded wheel tracking, flow number, semicircular bend, dissipated creep strain energy, and dynamic modulus tests, were performed to examine the physical and mechanical properties of the asphalt-treated mixtures. Mechanistic–Empirical Pavement Design Guide (MEPDG) software was used to compare the performance of low-volume pavement sections with asphalt-treated mixtures to that of a conventional hot-mix asphalt (HMA) mixture. Life-cycle assessment was also conducted to quantify the environmental impacts of using asphalt-treated mixtures in lieu of conventional HMA mixtures in the construction of low-volume roads. Test results demonstrated that asphalt-treated mixtures containing limestone and reclaimed asphalt pavement exhibited similar properties to those of well-performing conventional HMA mixtures. MEPDG analysis showed that pavement sections with asphalt-treated mixtures exhibited similar performance to those with conventional low-volume HMA mixtures. Life-cycle assessment indicated that using asphalt-treated mixtures in low-volume roads could result in reductions of up to 29% in carbon dioxide emissions, 29% in energy consumption, 39% in water consumption, and 42% in hazardous waste generation.

Verification of Virtual Climatic Data in MEPDG Using the LTPP Database

The Enhanced Integrated Climatic Model (EICM) integrated in the Mechanistic-Empirical Pavement Design Guide (MEPDG) allows users to select adjacent weather stations to generate a virtual weather station (VWS), whose data are further used to predict environmental impact on pavement performance. It is essential that the derived virtual data be accurate and representative of the actual climatic conditions. To evaluate the accuracy of the MEPDG generated VWS data, climatic data from corresponding automated weather stations (AWS) in the long-term pavement performance (LTPP) database are obtained to conduct the comparison analysis. It is observed that most VWS climatic data estimate the actual weather data reasonably well. However, in some cases, significant differences are observed. The potential factors resulting in the discrepancies are investigated. MEPDG analyses are conducted to quantify the climate data differences on predicted pavement performance. Finally, the paper presents recommendations when using the MEPDG software to generate VWS so as to help establish more accurate key climatic inputs.

Material-specific effects of hydrated lime on the properties and performance behavior of asphalt mixtures and asphaltic pavements

This study evaluates hydrated lime-treated hot-mix asphalt (HMA) mixtures through various laboratory tests, including the dynamic modulus test and performance tests to characterize permanent deformation and fatigue damage resistance both in displacement-controlled and force-controlled modes. Two different asphalt mixtures — the asphalt concrete mixture and the fine aggregate asphalt matrix mixture — which differ only in the amount of additional hydrated lime (0.5–3.0%), are tested. Test results demonstrate material-specific damage characteristics of hydrated lime and the existence of a more appropriate amount of hydrated lime to be added to the HMA mixtures than the current typical application rate such as the addition of 1.0% lime to dry or pre-moistened aggregates. In addition, the newly released Mechanistic-Empirical Pavement Design Guide (MEPDG) is used for predicting pavement performance related to hydrated lime content. The MEPDG analysis results show that damage prediction models implemented in the current MEPDG are limited to accurately predicting material-specific damage characteristics. Mechanistic models that consider material-specific crack phenomenon and fracture behavior should be pursued.

Determination of the appropriate representative elastic modulus for asphalt concrete

The National Cooperative Highway Research Program (NCHRP) 1-37A mechanistic-empirical pavement design guide (MEPDG) utilises the dynamic modulus of asphalt concrete in a multilayered elastic analysis to determine the primary responses in asphalt pavements. The dynamic modulus depends on temperature and loading frequency. In the MEPDG, the pulse time is used to determine the loading frequency. This methodology has been under scrutiny due to the large modulus it estimates. This paper evaluates several approximation methods, including the current MEPDG analysis, for the calculation of stresses and strains in linear viscoelastic materials by comparing analysis results with the solutions from the exact linear viscoelastic analysis. Sources of the errors that result from various approximation methods are discussed. Also, an alternative method to that of the MEPDG is proposed for determining the appropriate representative elastic modulus of asphalt concrete.

A preliminary study of the mechanical properties of asphalt mixture containing bottom ash

This paper shows a preliminary study of asphalt mixtures containing bottom ash with a primary focus on the permanent deformation. The objectives of this study are (i) perform literature reviews on the mechanical properties of asphalt mixtures containing bottom ash; (ii) evaluate the effects of using bottom ash as the mineral filler for the asphalt mixture through the flow number and dynamic modulus tests; and (iii) use the test results to evaluate the pavement permanent deformation using the Mechanistic–empirical pavement design guide (MEPDG) analysis. It was found that the asphalt mixture using bottom ash uses higher asphalt content due to the higher absorption. The replacement with bottom ash in the asphalt mixture generates a lower dynamic modulus as compared to the control mixtures. Additionally, results from MEPDG analysis show mixtures with bottom ash have higher rutting potential.