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.

scholarly journals Propagation of Surface Waves in Asphalt Pavements Generated by Different Load Impulse of Falling Weight Deflectometer

2019 ◽  
Vol 15 (1) ◽  
pp. 29-35
Author(s):  
Jozef Komačka ◽  
IIja Březina
Keyword(s):  
Surface Waves ◽  
Travel Time ◽  
Time History ◽  
Asphalt Pavements ◽  
Load Force ◽  
Falling Weight Deflectometer ◽  
Waves Propagation ◽  
Propagation Of Waves ◽  
Falling Weight ◽  
The Waves

Abstract The propagation of waves generated by load impulse of two FWD types was assessed using test outputs in the form of time history data. The calculated travel time of wave between the receiver in the centre of load and others receivers showed the contradiction with the theory as for the receivers up to 600 (900) mm from the centre of load. Therefore, data collected by the sensors positioned at the distance of 1200 and 1500 mm were used. The influence of load magnitude on the waves propagation was investigated via the different load force with approximately the same load time and vice versa. Expectations relating to the travel time of waves, depending on the differences of load impulse, were not met. The shorter travel time of waves was detected in the case of the lower frequencies. The use of load impulse magnitude as a possible explanation was not successful because opposite tendencies in travel time were noticed.

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.

Influence of Cracking Damage on Deflection Basin Test Data of FWD

2014 ◽  
Vol 620 ◽  
pp. 55-60 ◽  
Author(s):  
Xin Qiu ◽  
Xiao Hua Luo ◽  
Qing Yang
Keyword(s):  
Probabilistic Approach ◽  
Asphalt Pavements ◽  
Falling Weight Deflectometer ◽  
Layer System ◽  
Linear Elastic ◽  
Distribution Features ◽  
Pavement Structures ◽  
And Performance ◽  
Falling Weight ◽  
Non Destructive

With the popularization of falling weight deflectometer (FWD) to calculate the stiffness related parameters of the pavement structures, non-destructive evaluation of physical properties and performance of pavements has taken a new direction. FWD backcalculation is mathematically an inverse problem that could be solved either by deterministic or by probabilistic approach. A review of the currently used backcalculation procedures indicates that the calculation is generally based on a homogeneous, continuous, and linear elastic multi-layer system. Identifying effective data of dynamic deflection basins seems to be an important task for performing modulus backcalculation. Therefore, the main objective of this paper was to discuss the distribution features of dynamic deflection basins of asphalt pavements with crack distresses, and present the reasonable criteria to filter the testing data of FWD deflection basins. Finally, the study aims to validate the established criteria by conducting in-situ case study.

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.

scholarly journals Effects of Asphalt Mix Design Properties on Pavement Performance: A Mechanistic Approach

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Ahmad M. Abu Abdo ◽  
S. J. Jung
Keyword(s):  
Asphalt Concrete ◽  
Asphalt Pavement ◽  
Binder Content ◽  
Mix Design ◽  
Pavement Performance ◽  
Dynamic Shear Modulus ◽  
Test Results ◽  
Analysis Software ◽  
Mechanistic Approach ◽  
Asphalt Mix

The main objective of this study was to investigate the effects of hot mix asphalt material properties on the performance of flexible pavements via mechanistic approach. 3D Move Analysis software was utilized to determine rutting and cracking distresses in an asphalt concrete (AC) layer. Fourteen different Superpave mixes were evaluated by utilizing results of the Dynamic Modulus (|E⁎|) Test and the Dynamic Shear Modulus (|G⁎|) Test. Results showed that with the increase of binder content, the tendency of rutting in AC layer increased. However, with the increase of binder content, the cracking of AC layer lessened. Furthermore, when different binder grades were evaluated, results showed that with the increase of the upper binder grade number, rutting decreased, and with the increase of the lower binder grade number, rutting increased. Furthermore, analysis showed that with the increase of the lower binder grade number, higher percent of bottom up cracks would result. As a result of the analysis, binder grade should not be solely considered for cracking in AC layer; binder content and aggregate structure play a big role. Finally, results illustrated that the mechanistic approach is a better tool to determine the performance of asphalt pavement than commonly used methods.

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.

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