scholarly journals The Application of Frequency-Temperature Superposition Principle for Back-Calculation of Falling Weight Deflectometer

2019 ◽  
Vol 10 (1) ◽  
pp. 132
Author(s):  
Jung-Chun Lai ◽  
Jung Liu ◽  
Chien-Wei Huang
Keyword(s):  
Evaluation Model ◽  
Superposition Principle ◽  
Test Site ◽  
Temperature Correction ◽  
Falling Weight Deflectometer ◽  
Temperature Superposition ◽  
Back Calculation ◽  
Falling Weight ◽  
Frequency Temperature

The falling weight deflectometer (FWD) is a widely used nondestructive test (NDT) device in pavement infrastructure. A FWD test measures the surface deflections subjected to an applied impact loading and the modulus of pavement layers can be determined by back-calculating the measured deflections. However, the modulus of asphalt layers is significantly influenced by temperature; hence, the temperature correction must be considered in back-calculation to evaluate the moduli of asphalt layers at a reference temperature. In addition, the in situ temperature at various pavement depths is difficult to measure. A model for evaluating the temperature at various depths must be established to estimate the in situ temperature of asphalt layers. This study collected the temperature data from a FWD test site to establish a temperature-evaluation model for various depths. The cored specimens from the test site were obtained to conduct dynamic modulus tests for asphalt layers. The FWD tests were applied at the FWD test site and the back-calculation was performed with temperature correction using the frequency-temperature superposition principle. The back-calculated moduli of asphalt layers were compared with the master curve of dynamic modulus to verify the application of the frequency-temperature superposition principle for FWD back-calculation. The results show that the proposed temperature-evaluation model can effectively evaluate the temperature at various depths of pavement. Moreover, the frequency-temperature superposition principle can be effectively employed to conduct temperature correction for FWD back-calculation.

Influence of inertia on falling weight deflectometer (FWD) test response

1995 ◽  
Vol 32 (6) ◽  
pp. 1044-1048 ◽  
Author(s):  
Dieter F.E. Stolle ◽  
Gabriel Sedran
Keyword(s):  
Displacement Field ◽  
Load Distribution ◽  
Structural Integrity ◽  
Inertial Forces ◽  
Falling Weight Deflectometer ◽  
Ritz Vector ◽  
First Order ◽  
Back Calculation ◽  
Falling Weight

This note addresses the appropriateness of adopting an elastostatic model for backcalculating in situ layer moduli from falling weight deflectometer (FWD) data. By approximating the elastodynamic displacement field using an elastostatic solution for a given load distribution, it is shown via Ritz vector analyses that elastostatic fields do not accurately represent the displacements associated with pavements subjected to FWD-type loading. Some improvement is, however, possible by including first-order corrections for inertial forces. The main conclusion stemming from the analyses is that elastostatic models should not be used to estimate in situ moduli. Key words : pavement, elastodynamic analysis, Ritz vectors, back-calculation, structural integrity.

Temperature Correction on Falling Weight Deflectometer Measurements

2000 ◽  
Vol 1716 (1) ◽  
pp. 30-39 ◽  
Author(s):  
Dar-Hao Chen ◽  
John Bilyeu ◽  
Huang-Hsiung Lin ◽  
Mike Murphy
Keyword(s):  
Close Agreement ◽  
Temperature Correction ◽  
Falling Weight Deflectometer ◽  
Temperature Dependent ◽  
Different Seasons ◽  
Falling Weight ◽  
Correction Equations

Repeated falling weight deflectometer (FWD) tests were conducted at three sites. The tests were conducted at regular intervals for 2 to 3 consecutive days per location, and also done during different seasons in order that the widest possible range of temperatures could be obtained. The influence of cracks on temperature correction was also investigated. Temperature correction equations for deflection and moduli were developed so that users could be allowed to input their own reference temperatures. For all test pads, only the W1 and W2 deflections were found to be significantly affected by temperature. Comparisons with other reported temperature correction equations showed close agreement for deflection, but not for moduli. Tests were also run on cracked locations. Temperature did not affect the response of the cracked pavement as much as it did the intact pavement. Due to the different temperature-dependent characteristics of intact and cracked locations, the equations developed from the intact locations may not be used on cracked locations.

Temperature Correction of Backcalculated Moduli and Deflections Using Linear Viscoelasticity and Time-Temperature Superposition

1997 ◽  
Vol 1570 (1) ◽  
pp. 108-117 ◽  
Author(s):  
Sun Woo Park ◽  
Y. Richard Kim
Keyword(s):  
Linear Viscoelasticity ◽  
Superposition Principle ◽  
Asphalt Mixture ◽  
Temperature Shift ◽  
Relaxation Modulus ◽  
Analytical Description ◽  
Shift Factor ◽  
Temperature Correction ◽  
Temperature Superposition ◽  
Time Temperature Superposition

New analytical procedures for temperature correction of backcalculated asphalt concrete moduli and surface deflections were developed based on the theory of linear viscoelasticity and the time-temperature superposition principle and verified using falling weight deflectometer data and field temperature measurements. The new correction procedures explicitly utilize the thermorheological properties of the asphalt mixture. The resulting temperature-modulus correction factors depend only on the relaxation modulus and time-temperature shift factor of the mixture. The temperature-deflection correction factor depends on both the material properties and the layer thicknesses of the pavement section. Emphasis has been placed on the analytical description of the mixture’s thermoviscoelasticity responsible for temperature effects on mixture modulus and pavement deflection. A mechanistic framework for dealing with temperature correction problems for asphalt pavement has been introduced.

A Method for Temperature Correction of HMA Dynamic Modulus

2012 ◽  
Vol 178-181 ◽  
pp. 1615-1618 ◽  
Author(s):  
Ya Li Ye ◽  
Chuan Yi Zhuang ◽  
Ren Feng Zhang
Keyword(s):  
Dynamic Modulus ◽  
Asphalt Mixture ◽  
Temperature Correction ◽  
Reference Temperature ◽  
Wheel Load ◽  
Pavement Deterioration ◽  
Design Guide ◽  
Falling Weight ◽  
Asphalt Concrete Pavement

HMA dynamic modulus is one of key inputs to the Mechanistic-Empirical Pavement Design Guide. In order to analyze and evaluate bearing capacity of asphalt concrete pavement and to determinate the rules of pavement deterioration of modulus of asphalt layer under repeated wheel load and ambient, temperature correction for HMA is applied to the modulus so as to compare them with the same temperature. In order to get temperature correction coefficients for HMS moduli, a method of temperature correction for HMA moduli was put forward. In this method, the specimen of asphalt mixture or HMA cores from in-situ pavements were tested by Superpave Simple Performance Tester(SPT), or falling weight deflection(FWD) was tested on the site of in-situ pavements. The correlation between HMA dynamic modulus and temperature was regressed, and then dynamic modulus regression model was put forward. Results show that exponential function was fitted to the data to determine and adjust the modulus to a reference temperature, the recommendation regression equation can reflect the features of asphalt mixture at the reference temperature.

scholarly journals Application of FWD data in developing dynamic modulus master curves of in-service asphalt layers

2017 ◽  
Vol 23 (5) ◽  
pp. 661-671 ◽  
Author(s):  
Nader SOLATIFAR ◽  
Amir KAVUSSI ◽  
Mojtaba ABBASGHORBANI ◽  
Henrikas SIVILEVIČIUS
Keyword(s):  
Dynamic Modulus ◽  
Master Curve ◽  
Asphalt Pavements ◽  
Falling Weight Deflectometer ◽  
Master Curves ◽  
Simple Method ◽  
High Frequencies ◽  
Design Guide ◽  
Falling Weight

This paper presents a simple method to determine dynamic modulus master curve of asphalt layers by con­ducting Falling Weight Deflectometer (FWD) for use in mechanistic-empirical rehabilitation. Ten new and rehabilitated in-service asphalt pavements with different physical characteristics were selected in Khuzestan and Kerman provinces in south of Iran. FWD testing was conducted on these pavements and core samples were taken. Witczak prediction model was used to predict dynamic modulus master curves from mix volumetric properties as well as the bitumen viscosity characteristics. Adjustments were made using FWD results and the in-situ dynamic modulus master curves were ob­tained. In order to evaluate the efficiency of the proposed method, the results were compared with those obtained by us­ing the developed procedure of the state-of-the-practice, Mechanistic-Empirical Pavement Design Guide (MEPDG). Re­sults showed the proposed method has several advantages over MEPDG including: (1) simplicity in directly constructing in-situ dynamic modulus master curve; (2) developing in-situ master curve in the same trend with the main predicted one; (3) covering the large differences between in-situ and predicted master curve in high frequencies; and (4) the value obtained for the in-situ dynamic modulus is the same as the value measured by the FWD for a corresponding frequency.

scholarly journals Assessment Of Designed And Measured Mechanistic Parameters Of Concrete Pavement Foundation

2019 ◽  
Vol 14 (1) ◽  
pp. 37-57
Author(s):  
Yang Zhang ◽  
Pavana Vennapusa ◽  
David Joshua White
Keyword(s):  
California Bearing Ratio ◽  
Cone Penetrometer ◽  
Falling Weight Deflectometer ◽  
In Situ Tests ◽  
Target Value ◽  
Dynamic Cone Penetrometer ◽  
Support Conditions ◽  
Falling Weight ◽  
Pavement Foundation

There are plenty of in situ tests available to examine pavement foundation performance regarding stiffness and support conditions. This study evaluates several in situ tests of the stiffness and support conditions of concrete pavement foundation layers. The principal objective of this study was to evaluate the outputs from Dynamic Cone Penetrometer tests and Falling Weight Deflectometer tests. The California Bearing Ratio from Dynamic Cone Penetrometer tests and the deflection data from Falling Weight Deflectometer tests were correlated to the design parameter – modulus of subgrade reaction k through correlations employed in pavement design manuals. Three methods for obtaining the k values were conducted, with the intent to evaluate which method provides the results most similar to the target value and whether the studied correlations are reliable. The back-calculated k values from Falling Weight Deflectometer deflections and the weak layer California Bearing Ratio correlated k values based on the Portland Cement Association method were close to the target value, while the California Bearing Ratio empirically correlated k based on the American Association of State Highway and Transportation Officials method presented values significantly higher than the target value. Those previously reported correlations were likely to overestimate the k values based on subgrade California Bearing Ratio values.

Visco-Elastic Back-Calculation of Traffic Speed Deflectometer Measurements

2019 ◽  
Vol 2673 (12) ◽  
pp. 439-448 ◽  
Author(s):  
Christoffer P. Nielsen
Keyword(s):  
Calculation Procedure ◽  
Falling Weight Deflectometer ◽  
Calculation Algorithm ◽  
Structural Evaluation ◽  
Driving Speed ◽  
Back Calculation ◽  
Traffic Speed ◽  
Falling Weight ◽  
Calculation Procedures ◽  
Project Level

The traffic speed deflectometer (TSD) has proven a valuable tool for network level structural evaluation. At the project level, however, the use of TSD data is still quite limited. An obstacle to the use of TSD at the project level is that the standard approaches to back-calculation of pavement properties are based on the falling weight deflectometer (FWD). The FWD experiment is similar, but not equivalent, to the TSD experiment, and therefore it is not straightforward to apply the traditional FWD back-calculation procedures to TSD data. In this paper, a TSD-specific back-calculation procedure is presented. The procedure is based on a layered linear visco-elastic pavement model and takes the driving speed of the vehicle into account. This is in contrast to most existing back-calculation procedures, which treat the problem as static and the pavement as purely elastic. The developed back-calculation procedure is tested on both simulated and real TSD data. The real TSD measurements exhibit significant effects of damping and visco-elasticity. The back-calculation algorithm is able to capture these effects and yields model fits in excellent agreement with the measured values.

Use of falling weight deflectometer time history data for the analysis of seasonal variation in pavement response

2010 ◽  
Vol 37 (9) ◽  
pp. 1224-1231 ◽  
Author(s):  
Kate Deblois ◽  
Jean-Pascal Bilodeau ◽  
Guy Doré
Keyword(s):  
Phase Angle ◽  
Time History ◽  
Test Site ◽  
Flexible Pavement ◽  
Dissipated Energy ◽  
Falling Weight Deflectometer ◽  
History Data ◽  
The Road ◽  
Pavement Structures ◽  
Falling Weight

This paper presents the results of an exploratory analysis of falling weight deflectometer (FWD) data collected on a large project about the spring thaw behaviour of pavements. The test site includes four test sections, two of which are conventional flexible pavement structures, whereas the other two are built with a cement-treated base. The aim of this study is to verify the applicability of using FWD time history data to evaluate damage to a road during the thawing period. The applicability of the analysis techniques is verified through the phase angle and dissipated energy. The data analyzed were obtained from tests conducted with an FWD on one flexible pavement test section. The results obtained showed a clear difference between the winter, thawing, and summer periods. It was found that the phase angle and dissipated energy can be used to evaluate the road damage during the thawing period through quantification of the phase angle and dissipated energy. These factors can also be used to describe the pavement behaviour in terms of elasticity and viscoelasticity.

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