The resilient modulus of subgrade is one of the important parameters for the design of pavements, including the estimation of permanent deformation (rutting) in the current Mechanistic-Empirical Pavement Design Guide (MEPDG). Find a library where document is available. Subgrade of roadways is subjected to repeated traffic loading at different loading intensities.This study was designed to assist MDOT in the implementation of the M-E PDG and to improve the accuracy of the inputs to the existing 1993 AASHTO Design Guide. The proposed procedure discusses pre-analysis checks, seed modulus adjustment, pavement structure adjustment and program termination criteria. requires the determination of the resilient modulus values from either backcalculation or from laboratory tests. The protocol is intended for use on a flexible pavement with a crushed base. Recommendations to improve the accuracy of the backcalculated |E*| mastercurve are provided in the context of enhancing current FWD technology and test procedures. a systematic back-calculation protocol for subgrade resilient modulus using MODCOMP6 software. With deflection time histories from a typical FWD test, it was possible to backcalculate the relaxation modulus curve, E(t), up to about t ~ 10 to the -1 power s and the complex modulus curve, |E*|, from f = 10 to the -3 power Hz and above. The method uses a layered viscoelastic forward algorithm in an iterative backcalculation procedure for linear viscoelastic characteristics of asphalt pavements.
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A methodology backcalculates the |E*| mastercurve of the asphalt pavement layer by using the time history of FWD surface deflections. 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.
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One of the key inputs in the MEPDG for asphalt pavements is the dynamic modulus (|E*|) mastercurve. 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. 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). Six programs were selected for detailed evaluation - ELCON and ELI-BACK for rigid pavement, and ISSEM4, MODCOMP3, MODULUS and WDEF for flexible pavements. The corrected back-calculation moduli are reasonable and close to the splitting moduli, and its data variation is smaller than that of the uncorrected back-calculation moduli.Backcalculation of Dynamic Modulus Mastercurve from Falling Weight Deflectometer Surface Deflections The results show that the quintic polynomial is effective at eliminating the noise information of deflection basin. The back-calculated moduli (with and without deflection basin correction) were compared, and splitting moduli from coring samples of the surface asphalt layer were additionally compared for partial validation. Efforts have been made in this paper to backcalculate the in situ elastic moduli of asphalt pavement from synthetically derived falling weight deflectometer. Campus students are required to use it for their design activities. It is available at the Highway Design Lab (BEL 117). Read chapter I: Comparison of Laboratory and Backcalculated Resilient Moduli: NCHRP Web Doc 14 Laboratory Determination of Resilient Modulus for Flexible. This study develops a fuzzy model to backcalculate modulus of pavement layers. Pavement rehabilitation method and timing depend on the existing stiffness or modulus of pavement layer materials.
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Backcalculation modulus software#
This is a proprietary AASHTOWARE computer software product. Backcalculation of modulus values from Falling Weight Deflectometer (FWD) data is one of the most popular practices all over the world for pavement evaluation. DARWin 2.0 (Pavement Design, Analysis and Rehabilitation for Windows). The optimum mathematical regression model for the theoretical deflection basin without interference was analysed using the probabilistic density method, which was then applied to remove the noise information of the in–situ measured deflection basin. MODULUS 5.1 Backcalculation Program (Texas Transportation. The influence of noise, including the pavement surface condition and internal anomalies, on the deflection basin was studied. The noise in in–situ measured asphalt pavement deflection basin is the primary cause for the difference between the theoretical deflection basin in back-calculating software and measured basin, which affects the accuracy of the modulus back-calculation.