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Mercedes Solla - One of the best experts on this subject based on the ideXlab platform.
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evaluation of a highway pavement using non destructive tests falling weight Deflectometer and ground penetrating radar
Construction and Building Materials, 2017Co-Authors: Vânia Marecos, Simona Fontul, Mercedes Solla, Maria De Lurdes AntunesAbstract:Abstract This paper presents the results of the application of two non-destructive tests (NDT): Falling Weight Deflectometer (FWD) and Ground Penetrating Radar (GPR) to assess the bearing capacity of a flexible pavement. The main motivation of this research was the evaluation of the use of this two methodologies, over time-consuming, unsafe and costly traditional destructive methods, as a support for the decisions regarding pavement maintenance with concerns to its structural condition. The structural models were established based on the deflections from the FWD and using the design thickness and GPR measured thickness. The layers elastic moduli were estimated through back-calculation. The influence of having continuous accurate data on layer thickness was evaluated for a case study of a rehabilitated flexible highway pavement, in which surface cracking occurred only one year after reinforcement. The results show that the variability of the layers thicknesses was high and therefore the main focus was on the sensitivity of the estimated elastic moduli to the layers thicknesses. It was concluded that the thickness of the bound layers had a high influence on the estimated bituminous layers moduli and consequently on the pavement response models. Even though the results obtained are specific to this case study this research reinforced the importance of using GPR for continuous assessment of layer thickness together with load tests performed by FWD for an accurate structural evaluation of existing pavements. This paper is of interest for COST Action TU1208 Civil Engineering Applications of Ground Penetrating Radar.
Karim Chatti - One of the best experts on this subject based on the ideXlab platform.
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backcalculation of asphalt concrete modulus master curve from field measured falling weight Deflectometer data using a new time domain viscoelastic dynamic solution and genetic algorithm
Transportation Research Record, 2014Co-Authors: Imen Zaabar, Karim Chatti, Hyung Suk Lee, Nizar LajnefAbstract:A new backcalculation program, DYNABACK-VE, was used to backcalculate pavement layer properties with field data. DYNABACK-VE used a time domain viscoelastic dynamic solution (ViscoWave-II) as a forward routine and a genetic algorithm for backcalculation analysis. The genetic algorithm search method was selected because it had a high potential for converging efficiently to a global solution. The forward solution used continuous integral transforms (Laplace and Hankel) that were more appropriate for transient, nonperiodic signals in the time domain. The algorithm was implemented in C++ and coded for parallel processing with multithreading for achieving better computational efficiency. Field falling weight Deflectometer load and deflection sensor time histories from three sites (Waverly Road near Lansing, Michigan, and two long-term pavement performance sections) were used for validation. The backcalculated asphalt concrete modulus master curves were compared with those obtained from laboratory testing. Very...
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backcalculation of dynamic modulus mastercurve from falling weight Deflectometer surface deflections
Transportation Research Record, 2011Co-Authors: Emin M Kutay, Karim Chatti, Ligang LeiAbstract:The need to characterize the structural condition of existing pavements accurately has increased with the recent development, release, and ongoing implementation of the new Mechanistic-Empirical Pavement Design Guide (MEPDG). There is a strong need to identify and evaluate the way that falling weight Deflectometer (FWD) testing is operated and integrated into the new design procedure. One of the key inputs in the MEPDG for asphalt pavements is the dynamic modulus (|E*|) master-curve. If the damaged |E*| mastercurve of the asphalt concrete in an existing pavement can be obtained from FWD deflections, a more accurate prediction of its remaining service life can be achieved. A methodology backcalculates the |E*| mastercurve of the asphalt pavement layer by using the time history of FWD surface deflections. The method uses a layered viscoelastic forward algorithm in an iterative backcalculation procedure for linear viscoelastic characteristics of asphalt pavements. With deflection time histories from a typica...
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effective layer temperature prediction model and temperature correction via falling weight Deflectometer deflections
Transportation Research Record, 2001Co-Authors: Dong Yeob Park, Neeraj Buch, Karim ChattiAbstract:Surface deflections and backcalculated layer moduli of flexible pavements are significantly affected by the temperature of the asphalt concrete (AC) layer. The correction of these deflections and moduli to a reference temperature requires the determination of an effective temperature of the AC layer. In light of this, a new temperature prediction model for determination of the AC temperature on the basis of a database approach is presented, and temperature correction factors for AC modulus are developed. Temperature datum points (n = 317) and deflection profiles (n = 656) were collected from the six in-service test sites in Michigan. Temperature datum points (n = 197) from three of the test sites were used to develop the temperature prediction model, and data from the remaining sites were used for validation. The temperature prediction model developed has an R2 value greater than 90 percent and an F-statistic significantly greater than 1.0. For further validation of the temperature prediction model, tempe...
Munir D. Nazzal - One of the best experts on this subject based on the ideXlab platform.
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mechanistic approach to pavement vehicle interaction and its impact on life cycle assessment
Transportation Research Record, 2012Co-Authors: Mehdi Akbarian, S S Moeiniardakani, Franzjosef Ulm, Munir D. NazzalAbstract:The accuracy and the comprehensiveness of any pavement life-cycle assessment are limited by the ability of the supporting science to quantify the environmental impact. Pavement-vehicle interaction represents a significant knowledge gap that has important implications for many pavement life-cycle assessment studies. In the current study, the authors assumed that a mechanistic model that linked pavement structure and properties to fuel consumption could contribute to closing the uncertainty gap of pavement-vehicle interaction in life-cycle assessment of pavements. The simplest mechanistic pavement model, a Bernoulli-Euler beam on a viscoelastic foundation subjected to a moving load, was considered. Wave propagation properties derived from falling weight Deflectometer time history data of FHWA's Long-Term Pavement Performance program were used to calibrate top-layer and substrate moduli for various asphalt and concrete systems. The model was validated against recorded deflection data. The mechanistic respons...
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estimation of resilient modulus of subgrade soils using falling weight Deflectometer
Transportation Research Record, 2010Co-Authors: Munir D. Nazzal, Louay N MohammadAbstract:Field and laboratory testing programs were conducted to develop models that predict the resilient modulus (Mr) of subgrade soils from the falling weight Deflectometer (FWD) test results. Mr is used in the design and evaluation of pavement structures. The field testing program included testing various sections in 10 pavement projects within Louisiana. The tested sections covered the common subgrade soil types found in Louisiana. Three backcalculation software packages were used to interpret the FWD data: ELMOD 5.1.69, MODULUS 6.0, and EVERCALC 5.0. In addition, the AASHTO and Florida backcalculation equations were used for comparison. The laboratory testing program consisted of conducting repeated load triaxial Mr tests, physical properties, and compaction tests on soil samples obtained from tested sections. Statistical models were developed that can relate the laboratory measured Mr to FWD moduli backcalculated (EFWD) using each of the methods considered. The results of this study showed that the EFWD/Mr ...
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evaluating the light falling weight Deflectometer device for in situ measurement of elastic modulus of pavement layers
Transportation Research Record, 2007Co-Authors: Munir D. Nazzal, Murad Y Abufarsakh, Khalid A AlshibliAbstract:Field and laboratory testing programs were conducted to evaluate the potential use of the light falling weight Deflectometer (LFWD) device for measuring the in situ elastic modulus of pavement layers and subgrades. The field tests were conducted on several highway sections selected from different projects in Louisiana. In addition, nine test sections were constructed and tested at the Pavement Research Facility site of Louisiana Transportation Research Center. All sections were tested using the Prima 100 model-LFWD in conjunction with the falling weight Deflectometer (FWD), plate load test (PLT), and dynamic cone penetrometer (DCP) tests that were used as reference measurements. Linear regression analyses were carried out on the collected test data to develop models that could directly relate the LFWD stiffness modulus with moduli obtained from FWD and PLT and the DCP penetration rate. In addition, multiple nonlinear regression analyses were conducted to develop models that could predict FWD and PLT modul...
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assessment of in situ test technology for construction control of base courses and embankments
2004Co-Authors: Murad Y Abufarsakh, Khalid A Alshibli, Munir D. Nazzal, Ekrem SeymanAbstract:With the coming move from an empirical to mechanistic-empirical pavement design, it is essential to improve the quality control/quality assurance (QC/QA) procedures of compacted materials from a density-based criterion to a stiffness/strength-based criterion. The nondestructive in-situ tests such as the Geogauge, Dynamic Cone Penetrometer (DCP), and Light Falling Weight Deflectometer (LFWD) can be effective tools for assessing of subsurface conditions and evaluating the stiffness of pavement materials and embankments. This report evaluates the potential of these three devices to reliably measure the stiffness characteristics of highway materials for possible application in the QC/QA procedures during and after the construction of pavement layers and embankments. To achieve this, field and laboratory testing programs were conducted. The laboratory program included construction of different sections inside two boxes (5 x 3 x 2.5 ft) located at the Geosynthetic Engineering Research Laboratory (GERL) at the Louisiana Transportation Research Center (LTRC). The field tests were conducted on highway sections selected from various projects in Louisiana. In addition, six test sections and three trench sections were constructed and tested at the LTRC Pavement Research Facility (PRF) site. The field and laboratory tests included Geogauge, LFWD, and DCP tests in conjunction with two standard tests such as the Plate Load Test (PLT) and Falling Weight Deflectometer (FWD) test. The California Bearing Ratio (CBR) laboratory tests were also conducted on similar samples collected during the field and laboratory tests. A statistical analysis revealed good correlations between the measurements obtained from the three investigated devices and those obtained from the standard tests, thus demonstrating that the investigated devices can reliably measure the in-situ stiffness of highway materials, subgrades and embankments.
Emin M Kutay - One of the best experts on this subject based on the ideXlab platform.
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backcalculation of viscoelastic and nonlinear flexible pavement layer properties from falling weight deflections
International Journal of Pavement Engineering, 2016Co-Authors: Sudhir Varma, Emin M KutayAbstract:Appropriate characterisation of individual layer properties is crucial for mechanistic analysis of flexible pavements. Typically in inverse analyses, pavements are modelled as elastic or nonlinear elastic to obtain layer material properties through non-destructive falling weight Deflectometer (FWD) testing. In this study, a layered viscoelastic–nonlinear forward model (called LAVAN) was used to develop a genetic algorithm-based backcalculation scheme (called BACKLAVAN). The LAVAN can consider both the viscoelastic behaviour of asphalt concrete (AC) layer and nonlinear elastic behaviour of unbound layers. The BACKLAVAN algorithm uses FWD load-response history at different test temperatures to backcalculate both the (damaged) E(t) and |E*| master curve of AC layers and the linear and nonlinear elastic moduli of unbound layers of in-service pavements. The BACKLAVAN algorithm was validated using two FWD tests run on a long-term pavement performance section. Comparison between the backcalculated and measured r...
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viscoelastic genetic algorithm for inverse analysis of asphalt layer properties from falling weight deflections
Transportation Research Record, 2013Co-Authors: Sudhir Varma, Emin M Kutay, Eyal LevenbergAbstract:The falling weight Deflectometer (FWD) is a nondestructive test whose results are typically used for backcalculating in situ layer properties of pavements. Most backcalculation methods assume the pavement to be a layered elastic half-space. However, asphalt pavements behave more like multilayered viscoelastic systems, especially in response to small or short-duration load applications. Hence, although elastic analysis is computationally efficient and well accepted in the engineering community, the theory cannot produce the viscoelastic properties of the asphalt concrete (AC) layer. In this study, a new inverse analysis method is proposed to backcalculate both linear elastic and viscoelastic properties of pavement layers as well as the AC time-temperature shift factor. In this method, the FWD load-response history of a single FWD drop and variation in temperature along the depth of the AC layer during the drop are used for performing the computations. The underlying (viscoelastic) forward solver is approxi...
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backcalculation of dynamic modulus mastercurve from falling weight Deflectometer surface deflections
Transportation Research Record, 2011Co-Authors: Emin M Kutay, Karim Chatti, Ligang LeiAbstract:The need to characterize the structural condition of existing pavements accurately has increased with the recent development, release, and ongoing implementation of the new Mechanistic-Empirical Pavement Design Guide (MEPDG). There is a strong need to identify and evaluate the way that falling weight Deflectometer (FWD) testing is operated and integrated into the new design procedure. One of the key inputs in the MEPDG for asphalt pavements is the dynamic modulus (|E*|) master-curve. If the damaged |E*| mastercurve of the asphalt concrete in an existing pavement can be obtained from FWD deflections, a more accurate prediction of its remaining service life can be achieved. A methodology backcalculates the |E*| mastercurve of the asphalt pavement layer by using the time history of FWD surface deflections. The method uses a layered viscoelastic forward algorithm in an iterative backcalculation procedure for linear viscoelastic characteristics of asphalt pavements. With deflection time histories from a typica...
Nadarajah Sivaneswaran - One of the best experts on this subject based on the ideXlab platform.
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backcalculation of flexible pavement layer moduli from traffic speed Deflectometer data
Transportation Research Record, 2017Co-Authors: Mahdi Nasimifar, Senthilmurugan Thyagarajan, Nadarajah SivaneswaranAbstract:In the past few years, state transportation departments in the United States have been investigating the potential use of the traffic speed Deflectometer (TSD) in routine network-level pavement structural evaluation, including efforts to compute parameters typically obtained with the falling weight Deflectometer (FWD). However, differences in loading configuration (single plate versus dual tires) and mechanism (impact versus moving load) between the FWD and the TSD necessitate modification of conventional analysis methodologies for use with TSD data. The TSD is a trailer truck that uses Doppler lasers to measure the pavement deflection velocities at normal traffic speed. Deflection velocities are then converted to surface deflections with a computational algorithm. This study proposes two approaches to backcalculating layer moduli from the TSD data. The first method uses 3D-Move software and deflection velocities measured directly by the TSD. The 3D-Move software can closely simulate TSD loading by consid...