Characteristics of in-situ dynamic stresses of pavement subgrade under portable falling weight deflectometer test

2012 ◽  
pp. 593-597
Author(s):  
G Leung ◽  
Y Wang ◽  
A Wong
Keyword(s):  
Falling Weight Deflectometer ◽  
Dynamic Stresses ◽  
Falling Weight

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.

Relationship Between Backcalculated and Laboratory-Measured Resilient Moduli of Unbound Materials

2003 ◽  
Vol 1849 (1) ◽  
pp. 177-182 ◽  
Author(s):  
Gerardo W. Flintsch ◽  
Imad L. Al-Qadi ◽  
Youngjin Park ◽  
Thomas L. Brandon ◽  
Alexander Appea
Keyword(s):  
Resilient Modulus ◽  
Shift Factor ◽  
Falling Weight Deflectometer ◽  
Test Results ◽  
Structural Capacity ◽  
Bulk Stress ◽  
Stress Dependent ◽  
Falling Weight ◽  
Virginia Smart Road

The resilient moduli of an unbound granular subbase (used at the Virginia Smart Road) obtained from laboratory testing were compared with those backcalculated from in situ falling weight deflectometer deflection measurements. Testing was performed on the surface of the finished subgrade and granular subbase layer shortly after construction. The structural capacity of the constructed subgrade and the depth to a stiff layer were computed for 12 experimental sections. The in situ resilient modulus of the granular subbase layer (21-B) was then back-calculated from the deflections measured on top of that layer. The back-calculated layer moduli were clearly stress-dependent, showing an exponential behavior with the bulk stress in the center of the layer. Resilient modulus test results of laboratory-compacted specimens confirmed the stress dependence of the subbase material modulus. Three resilient modulus models were fitted to the data. Although all three models showed good coefficients of determination ( R2 > 90%), the K-θ model was selected because of its simplicity. The correlation between field-backcalculated and laboratory-measured resilient moduli was found to be strong. However, when the stress in the middle of the layer was used in the K-θ model, a shift in the resilient modulus, θ, was observed. This finding suggests that a simple shift factor could be used for the range of stress values considered.

The Use of the Dynamic Cone Penetrometer for Quality Control of Compaction Operations

2013 ◽  
Vol 10 ◽  
pp. 49-64
Author(s):  
Moshe Livneh ◽  
Noam A. Livneh
Keyword(s):  
Quality Control ◽  
Silty Sand ◽  
Granular Soils ◽  
Cone Penetrometer ◽  
Clayey Soils ◽  
Falling Weight Deflectometer ◽  
Dynamic Cone Penetrometer ◽  
Additional Testing ◽  
Falling Weight

The use of a new quality control (QC) and quality assurance (QA) specification involving Dynamic Cone Penetrometer (DCP) testing in concert with conventional moisture and density testing is becoming more and more frequent in various parts of the world. The need for this additional testing is essential, as the regular in-situ density tests cannot alone ensure the compliance of the layers constructed with the compaction requirements. Recent analyses of the correlation between the DCP testing and the California Bearing Ratio CBR testing show that QC and QA DCP testing is adequate to verify compaction, stability and vertical uniformity in both cohesive and granular soils. Two examples of DCP usage in two Israeli earthwork projects, one of clayey soils and the other of silty-sand soils, indicate the benefits of this usage along with, though for the clayey example only, Falling Weight Deflectometer (FWD) testing.

scholarly journals Preliminary In-Situ Evaluation of an Innovative, Semi-Flexible Pavement Wearing Course Mixture Using Fast Falling Weight Deflectometer

Materials ◽  
2018 ◽  
Vol 11 (4) ◽  
pp. 611 ◽  
Author(s):  
Chiara Pratelli ◽  
Giacomo Betti ◽  
Tullio Giuffrè ◽  
Alessandro Marradi
Keyword(s):  
Flexible Pavement ◽  
Falling Weight Deflectometer ◽  
Falling Weight

scholarly journals In Situ Assessment of Pavement Subgrade Using Falling Weight Deflectometer

2014 ◽  
Vol 43 (1) ◽  
pp. 20130149 ◽  
Author(s):  
Gary W. Chai ◽  
Rudi van Staden ◽  
Yew-Chaye Loo
Keyword(s):  
Falling Weight Deflectometer ◽  
In Situ Assessment ◽  
Falling Weight

Comparison of Simplified Elastostatic and Elastodynamic Models for Falling Weight Deflectometer Data Interpretation

1996 ◽  
Vol 1540 (1) ◽  
pp. 72-76
Author(s):  
Dieter F. E. Stolle
Keyword(s):  
Structural Integrity ◽  
Data Interpretation ◽  
Falling Weight Deflectometer ◽  
System Parameters ◽  
Dynamic Impedance ◽  
In Situ Conditions ◽  
Subgrade Modulus ◽  
Falling Weight

The characterization of pavements and subgrades by interpreting falling weight deflectometer data is discussed. Two backcalculation strategies—one based on an approximate elastostatic model and the other on dynamic impedance for a two-layered pavement subgrade system—are presented and applied to data collected along experimental pavement sections. Both strategies characterize the structural integrity of a pavement by equivalent asphalt thickness and the stiffness of the subgrade by effective subgrade modulus. It is indicated that, although both procedures predict similar trends, the values of the system parameters differ, particularly the equivalent asphalt thickness. The net pavement-subgrade stiffness predicted using dynamic impedance was found to be consistently higher than that obtained with the elastostatic model for the data studied. The capability of dynamic impedance to identify variations of in situ conditions along a section of roadway is also demonstrated.

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