Single-Measurement Estimation of In Situ Asphalt-Layer Moduli with Portable Falling Weight Deflectometer

1997 ◽  
Vol 1570 (1) ◽  
pp. 118-125 ◽  
Author(s):  
Moshe Livneh
Keyword(s):  
Testing Procedure ◽  
Testing Device ◽  
Falling Weight Deflectometer ◽  
Single Measurement ◽  
In Situ Tests ◽  
Technical Literature ◽  
Measuring Device ◽  
New Device ◽  
Falling Weight

The portable falling weight deflectometer (FWD) was introduced some time ago. The use of this measuring device in Israel was stimulated by the contradictory results of various studies described in the technical literature. These studies indicated that significant deviations may exist between the in situ FWD-backcalculated asphalt-layer moduli and the expected true moduli values from laboratory testing. In addition to these deviations, it is known that uncertainties associated with the backcalculation procedure do not allow the backcalculation of moduli for thin asphalt layers less than 75 to 100 mm thick. Therefore, the need for an additional in situ testing device that would produce reasonable results for the in situ asphalt-layer moduli became obvious. In Israel, the portable FWD was considered to be a promising testing device to serve this need. In situ tests showed that the new device required additional testing on the asphalt surface after coring the asphalt layers to their bottom. This type of double-testing enabled the derivation of the in situ asphalt-layer modulus using a straightforward backcalculating technique. It was also thought, however, that the double-testing procedure may be sometimes too clumsy and costly. Therefore, it was decided to examine the possibility of conducting a single measurement to obtain a good estimate of the asphalt-layer modulus. The current study led to a proposed procedure for estimating the in situ asphalt-layer modulus after only one run.

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.

Use of Locally Available Soils on Subbase and Base Layers of Flexible Pavements

2003 ◽  
Vol 1819 (1) ◽  
pp. 110-121 ◽  
Author(s):  
Lilian Ribeiro de Rezende ◽  
José Camapum de Carvalho
Keyword(s):  
Flexible Pavements ◽  
Federal District ◽  
Lateritic Soil ◽  
Crushed Rock ◽  
Falling Weight Deflectometer ◽  
In Situ Tests ◽  
Strain Behavior ◽  
Low Volume Roads ◽  
Falling Weight

Lateritic soils are very abundant in the region of the Federal District of Brazil. If this material could be used in low-volume roads, it would be possible to avoid some environmental problems. Alternative techniques were developed for the use of nonconventional materials as subbase and base layers of flexible pavements. To analyze the technical and economical viability of using local soils, two experimental highways were constructed. Each highway was divided into three sections with different materials in the subbase and base layers, such as fine lateritic soil, fine lateritic soil stabilized with lime, and a mixture of fine lateritic soil and crushed rock. The compaction characteristics were evaluated in laboratory tests. From the time the segments were constructed (in 1998 and 2000) until 2001, the stress–strain behavior of the paving structures was evaluated by in situ tests, such as the plate-bearing, Benkelman beam, and falling weight deflectometer tests. From the results, conclusions were drawn about which of the chosen materials showed the best performance in mechanical behavior.

scholarly journals Identification of Pavement Model Parameters in the Area of Discontinuous Surface Deformation Based on FWD Tests

2020 ◽  
Author(s):  
Marcin Grygierek ◽  
Krzysztof J. Sternik
Keyword(s):  
Surface Deformation ◽  
Elastic Half Space ◽  
Model Parameters ◽  
In Situ Tests ◽  
Discontinuous Surface ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic ◽  
Reinforcement Design ◽  
Falling Weight

Abstract Determination of the parameters of the pavement model in the linear discontinuous surface deformation (LDSD) area is presented in the article. The values are based on back calculations which involve results obtained from the elastic half-space model and the elastic—perfectly plastic model implemented in the finite element code compared with the results of the pavement deflection measured with Falling Weight Deflectometer (FWD). Based on the results of the calculations which have been matched to the results of the in situ measurements, the obtained values of the parameters of the pavement model within LDSD zone and outside it, were analysed. The results of pavement tests indicate at least a threefold increase in pavement deflections in the discontinuous deformation zone compared to deflections in the sections not affected by LDSD. The results of in situ tests and computational analysis presented in the paper allow their use in pavement reinforcement design in the area of anticipated LDSD.

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.

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
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