Rutting Development in Linear Tracking Test Pavements To Evaluate Shell Subgrade Strain Criterion

1997 ◽  
Vol 1570 (1) ◽  
pp. 23-29 ◽  
Author(s):  
J. Groenendijk ◽  
C. H. Vogelzang ◽  
A. Miradi ◽  
A. A. A. Molenaar ◽  
L. J. M. Dohmen
Keyword(s):  
Data Analysis ◽  
Shear Deformation ◽  
Asphalt Concrete ◽  
Heavy Traffic ◽  
Falling Weight Deflectometer ◽  
Wheel Load ◽  
Strain Criterion ◽  
Average Criterion ◽  
Tracking Device ◽  
Falling Weight

Two full-depth gravel asphalt concrete (AC) pavements of 0.15- and 0.08-m thickness on a sand subgrade were loaded with 4 million and 0.65 million repetitions of a 75-kN super-single wheel load using the linear tracking device (LINTRACK), a heavy-traffic simulator. Frequent measurements of asphalt strains, temperatures, rutting, cracking, and falling weight deflectometer (FWD) were made. The data analysis of the rutting measurements indicates that all rutting could be ascribed to subgrade deformation (secondary rutting). No evidence was found of shear deformation within the asphalt layer (primary rutting). The data analysis also indicates that the observed rutting performance of the LINTRACK test sections (to a maximum rut depth of 18 mm) coincides closely with the average criterion from the Shell Pavement Design Manual, which relates subgrade strain to allowable number of strain repetitions.

Effectiveness of static and dynamic backcalculation approaches for asphalt pavement

2020 ◽  
Vol 47 (7) ◽  
pp. 846-855
Author(s):  
Dandan Cao ◽  
Changjun Zhou ◽  
Yanqing Zhao ◽  
Guozhi Fu ◽  
Wanqiu Liu
Keyword(s):  
Asphalt Concrete ◽  
Elastic Moduli ◽  
Complex Modulus ◽  
Asphalt Pavement ◽  
Falling Weight Deflectometer ◽  
Fixed Frequency ◽  
Dynamic Approach ◽  
Layer Effect ◽  
Static Approach ◽  
Falling Weight

In this study, the field falling weight deflectometer (FWD) data for asphalt pavement with various base types were backcalculated through dynamic and static backcalculation approaches, and the effectiveness of backcalculation approaches was studied. Asphalt concrete (AC) was treated as a viscoelastic material and the complex modulus was obtained using the dynamic approach. The dynamic modulus at a fixed frequency was computed for comparison purposes. The coefficient of variance and the compensating layer effect were assumed as two characteristics for the effectiveness of backcalculation approaches. The results show that the layer property from the dynamic backcalculation approach for different stations were more consistent and showed smaller coefficient of variance, which were more appropriate for the characterization pavement behavior. The elastic moduli from the static approach were more variable and exhibited a compensating layer effect in which a portion of the modulus of one layer was backcalculated into other layers. The dynamic approach is more effective than static approaches in backcalculation of layer properties.

Mechanistic-Based Approach to Utilize Traffic Speed Deflectometer Measurements in Backcalculation Analysis

2020 ◽  
Vol 2674 (5) ◽  
pp. 208-222
Author(s):  
Zia U. A. Zihan ◽  
Mostafa A. Elseifi ◽  
Patrick Icenogle ◽  
Kevin Gaspard ◽  
Zhongjie Zhang
Keyword(s):  
Asphalt Concrete ◽  
Traffic Control ◽  
Parametric Study ◽  
Complex Modulus ◽  
Falling Weight Deflectometer ◽  
Software Application ◽  
Traffic Speed ◽  
Definition Of ◽  
Falling Weight ◽  
Surface Deflections

Backcalculation analysis of pavement layer moduli is typically conducted based on falling weight deflectometer (FWD) deflection measurements; however, the stationary nature of the FWD requires lane closure and traffic control. In recent years, traffic speed deflection devices such as the traffic speed deflectometer (TSD), which can continuously measure pavement surface deflections at traffic speed, have been introduced. In this study, a mechanistic-based approach was developed to convert TSD deflection measurements into the equivalent FWD deflections. The proposed approach uses 3D-Move software to calculate the theoretical deflection bowls corresponding to FWD and TSD loading configurations. Since 3D-Move requires the definition of the constitutive behaviors of the pavement layers, cores were extracted from 13 sections in Louisiana and were tested in the laboratory to estimate the dynamic complex modulus of asphalt concrete. The 3D-Move generated deflection bowls were validated with field TSD and FWD data with acceptable accuracy. A parametric study was then conducted using the validated 3D-Move model; the parametric study consisted of simulating pavement designs with varying thicknesses and material properties and their corresponding FWD and TSD surface deflections were calculated. The results obtained from the parametric study were then incorporated into a Windows-based software application, which uses artificial neural network as the regression algorithm to convert TSD deflections to their corresponding FWD deflections. This conversion would allow backcalculation of layer moduli using TSD-measured deflections, as equivalent FWD deflections can be used with readily available tools to backcalculate the layer moduli.

Estimation of tensile strains at the bottom of asphalt concrete layers under wheel loading using deflection basins from falling weight deflectometer tests

2012 ◽  
Vol 39 (7) ◽  
pp. 771-778 ◽  
Author(s):  
Jean-Pascal Bilodeau ◽  
Guy Doré
Keyword(s):  
Asphalt Concrete ◽  
Tensile Strain ◽  
Analysis Tool ◽  
Falling Weight Deflectometer ◽  
Proposed Model ◽  
Mechanistic Analysis ◽  
Pavement Engineering ◽  
Wheel Loading ◽  
Using Data ◽  
Falling Weight

The falling weight deflectometer is a pavement analysis tool that is now widely used in the pavement engineering field. Using the backcalculation process and the measured deflection basin, the layers moduli can be determined and a mechanistic analysis of the pavement can be made. A new approach is proposed to bypass the necessity of the backcalculation by allowing a direct estimation of the tensile strain at the bottom of asphalt concrete using the deflection basin. A model based on a finite element theoretical pavement analysis is proposed for this purpose. Complementary models have been developed to use the proposed models without having to determine the layers moduli. The proposed model to estimate the tensile strain at the bottom of the asphalt concrete layers is validated and calibrated using data obtained on an instrumented experimental site.

Structural Layer Coefficients of Crumb Rubber–Modified Asphalt Concrete Mixtures

1997 ◽  
Vol 1583 (1) ◽  
pp. 62-70 ◽  
Author(s):  
Mustaque Hossain ◽  
Affan Habib ◽  
Todd M. Latorella
Keyword(s):  
Asphalt Concrete ◽  
Crumb Rubber ◽  
Asphalt Pavements ◽  
Falling Weight Deflectometer ◽  
Average Value ◽  
Concrete Mixtures ◽  
Mechanistic Approach ◽  
Asphalt Mix ◽  
Falling Weight ◽  
Structural Layer

Structural layer coefficients for crumb rubber–modified (CRM) asphalt concrete mixtures were developed from the backcalculated moduli values using the falling weight deflectometer (FWD) test results on in situ pavements. Several test sections of recently built crumb rubber–modified pavements on three routes in Kansas (I-135, K-32 and US-56) were selected for this study. I-135 is a newly built asphalt pavement and the other two are gap-graded CRM overlays. Deflection data were collected with a Dynatest 8000 FWD at 21 locations at 7.5-m intervals on each test section on I-135, 22 locations on K-32, and 11 locations on US-56. For CRM asphalt mix overlays, the average surface layer coefficients from the equal mechanistic approach of analysis were found to vary between 0.11 and 0.46 with most values falling around 0.30. This indicates a lower structural layer coefficient value for the asphalt-rubber mix compared with the conventional asphalt concrete. For newly constructed CRM asphalt pavements, the structural layer coefficients varied from 0.25 to 0.48, with the average value around 0.35. These values are close to the design layer coefficient values used for conventional asphalt concrete layers. Large variabilities in computed structural layer coefficients for the rubblized jointed reinforced concrete pavement were observed. The structural layer coefficients computed for this layer varied from 0.10 to 0.35.

New Approach to Construct Master Curve of Damaged Asphalt Concrete Based on Falling Weight Deflectometer Back-Calculated Moduli

2016 ◽  
Vol 142 (11) ◽  
pp. 04016048 ◽  
Author(s):  
Van Phuc Le ◽  
Hyun Jong Lee ◽  
Julius Marvin Flores ◽  
Won Jae Kim ◽  
Jongeun Baek
Keyword(s):  
Asphalt Concrete ◽  
Master Curve ◽  
Falling Weight Deflectometer ◽  
New Approach ◽  
Falling Weight

Pavement Distress Under Accelerated Trafficking

1998 ◽  
Vol 1639 (1) ◽  
pp. 120-129
Author(s):  
Dar-Hao Chen
Keyword(s):  
Asphalt Concrete ◽  
Grid Size ◽  
Pavement Performance ◽  
Falling Weight Deflectometer ◽  
Pavement Distress ◽  
Structural Capacity ◽  
Surface Deflection ◽  
Load Simulator ◽  
Falling Weight ◽  
Asphalt Concrete Pavement

A test pad was closely monitored for a 6-month period, with 640,000 axle load repetitions applied to the test pavement. The load was applied by the Texas Mobile Load Simulator, a full-scale accelerated loading device. Pavement performance data, such as rutting and cracking, were collected at intervals of 0; 2,500; 5,000; 10,000; 20,000; 40,000; 80,000; 160,000; 320,000; and 640,000 axle repetitions. Falling weight deflectometer (FWD) tests were performed at these same data collection intervals to characterize the structural capacity of the pavement system. Although there is a trend indicating that locations with higher FWD deflection result in higher rutting, a unique relation to predict rutting accurately from the surface deflection alone was not found in the study. The back-calculated asphalt concrete pavement moduli were reduced by 50 percent of the original value at the end of 320,000 repetitions. However, the test was not terminated until 640,000 repetitions, when moduli were reduced to 40 percent of the original values. Both FWD deflection and percent of cracked area share the same trend; the left wheelpath had higher initial FWD deflections and later yielded a higher percentage of cracked area. Approximately 50 percent of the wheelpath area was cracked at the end of 80,000 repetitions, as measured by counting the number of cracked squares on a 100 mm by 100 mm grid. However, most of the cracks were hairline cracks. The percentage of cracked area is strongly related to the grid size used. A grid size of 100 mm by 100 mm has been recommended by other researchers and was adopted in this study. Eighty-five percent and 90 percent of the area in the wheelpaths was cracked at the end of 320,000 and 640,000 repetitions, respectively. These numbers are higher than those adopted by the Asphalt Institute, which defines failure as 45 percent cracking in the wheelpath.

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