Detection of Nonresilient Behavior in Pavements with a Falling-Weight Deflectometer

2003 ◽  
Vol 1860 (1) ◽  
pp. 26-32 ◽  
Author(s):  
David P. Orr
Keyword(s):  
Plastic Deformation ◽  
Moisture Content ◽  
Granular Materials ◽  
Load Level ◽  
Pavement Design ◽  
Falling Weight Deflectometer ◽  
Current Standard ◽  
Load Detection ◽  
Chi Squared ◽  
Falling Weight

The use of resilient models to describe the behavior of the materials in pavement design is the current standard. However, there are periods of the year when these resilient models may not be valid. Granular materials in pavements show some resiliency at every load level and moisture content. Nonresiliency is critical, however, when the plastic deformation becomes a large portion of the overall deformation in response to a load. Detection of possible nonresiliency in a pavement during use of a falling-weight deflectometer (FWD) would alert the FWD operator to possible nonresilient behavior. Two statistical checks are proposed to test for nonresiliency using the raw data provided by the FWD. Daily testing of a very weak pavement during spring thaw provided FWD data during and after a period of known nonresilient behavior. A chi-squared test of the variance may be able to detect nonresilient behavior.

Using Geogrids for Base Reinforcement as Measured by Falling Weight Deflectometer in Full-Scale Laboratory Study

1998 ◽  
Vol 1611 (1) ◽  
pp. 70-77 ◽  
Author(s):  
Thomas C. Kinney ◽  
Danielle Stone ◽  
John Schuler
Keyword(s):  
Design Procedure ◽  
Pavement Design ◽  
Silty Sand ◽  
Crushed Rock ◽  
Falling Weight Deflectometer ◽  
Base Course Material ◽  
Course Material ◽  
Base Course ◽  
Sand And Gravel ◽  
Falling Weight

A model road was constructed in a laboratory. The road consisted of asphalt over a crushed rock base and a silty sand and gravel subbase. The silty sand and gravel were placed in a very loose state to simulate a thaw-weakened, poor-quality subbase. The water table was kept at 152 mm (6 in.) below the bottom of the asphalt. The model road was divided into three sections. A geogrid was installed at the bottom of the base course material in two of the test sections, and the third was left as a control section. A falling weight deflectometer was used to measure the dynamic response of the pavement structure. The traffic benefit ratio is defined as the expected life (equivalent single-axle loads) of one section divided by the expected life of another section. The Alaska Department of Transportation and Public Facilities asphalt pavement design procedure and the NCHRP pavement design procedure were used to compare the test sections. The results from the two procedures were very similar. By using either procedure, the life of the pavement with respect to reinforcement was on the order of 2 to 4, depending on the type of grid and the depth of base course material.

Relating Laboratory and Field Moduli of Texas Base Materials

1998 ◽  
Vol 1639 (1) ◽  
pp. 1-11 ◽  
Author(s):  
S. Nazarian ◽  
J. Rojas ◽  
R. Pezo ◽  
D. Yuan ◽  
I. Abdallah ◽  
...  
Keyword(s):  
Resilient Modulus ◽  
Design Method ◽  
Field Tests ◽  
Pavement Design ◽  
Falling Weight Deflectometer ◽  
Nondestructive Tests ◽  
Second Stage ◽  
Base Materials ◽  
Two Stages ◽  
Falling Weight

Resilient modulus of base is an important parameter in the AASHTO pavement design method. However, the manner to determine this parameter is not well defined. Recent efforts in combining the resilient moduli from laboratory testing with those obtained in the field using nondestructive testing devices are presented. Laboratory tests were carried out in two stages. In the first stage, virgin materials from the quarry compacted to optimum moisture content were tested. In the second stage, similar base materials were retrieved from in-service roads. Specimens were prepared and tested at the corresponding field densities and moisture contents. Nondestructive tests were performed with the Falling Weight Deflectometer and the Seismic Pavement Analyzer. Based on tests on 10 different base materials from different parts of Texas, it was concluded that it may be difficult to directly compare moduli from laboratory and field tests; however, they can be combined for effective pavement design.

scholarly journals Influence of Temperature and Moisture Content on Pavement Bearing Capacity with Improved Subgrade

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3826 ◽  
Author(s):  
Vaitkus ◽  
Žalimienė ◽  
Židanavičiūtė ◽  
Žilionienė
Keyword(s):  
Moisture Content ◽  
Bearing Capacity ◽  
Asphalt Concrete ◽  
Structural Strength ◽  
Falling Weight Deflectometer ◽  
Influence Of Temperature ◽  
Surface Data ◽  
Seasonal Impact ◽  
Falling Weight ◽  
Electronic Sensors

Environmental conditions (temperature, moisture and the intensity of the sun) influence variation in asphalt pavement strength during the year. Lithuania is situated in a zone by average warm summers and average cold winters, and the most important climatic factor is the variation of the air temperature. This study presents the influence of temperature (of asphalt concrete (AC) and subgrade layers) and moisture content (of subgrade layers) to the pavement bearing capacity. The experimental research was obtained in five pavement sections of the experimental road. This experimental road was constructed in 2007 in Lithuania and is operated for more than 12 years. This paper presents a statistical analysis between the bearing capacity and the thickness of the asphalt concrete layers, the temperature and moisture content of different pavement layers, among sections, loaded and unloaded lanes (right and left wheel paths and tracks). The bearing capacity was evaluated by a falling weight deflectometer (FWD), temperature and moisture content by electronic sensors and thickness of AC layers by Georadar. Analysis of overall E0 and E0,h9 (bearing capacity at a depth of 9 cm from asphalt surface) data declares that seasonal impact on pavement structural strength due to a change of subgrade bearing capacity remains after correction of asphalt stiffness dependent on the temperature in the layer. However, it was detected that neither E0 nor E0,h9 are related to moisture content at a depths of 100 cm, 130 cm and 150 cm.

Efforts by North Carolina Department of Transportation to Develop Mechanistic Pavement Design System

1996 ◽  
Vol 1539 (1) ◽  
pp. 18-24
Author(s):  
Judith B. Corley-Lay
Keyword(s):  
North Carolina ◽  
First Generation ◽  
Design Procedure ◽  
Pavement Design ◽  
Design System ◽  
Falling Weight Deflectometer ◽  
Department Of Transportation ◽  
North Carolina Department ◽  
Falling Weight ◽  
Repetitions To Failure

A first generation mechanistic empirical pavement design procedure was developed using falling weight deflectometer deflections taken over a 3-year period at 16 test sections in Siler City, North Carolina. Information available for use in developing the procedure included deflection data, surface and air temperature, coring thicknesses at each test location, pavement performance records regarding rate of cracking, and traffic records. Jung's method, based on the curvature of the deflection bowl, was used to calculate strain at the bottom of the asphalt layer as a measure of fatigue. This calculated strain was used to obtain a calculated number of load repetitions to failure. Comparision of actual loads to failure with calculated loads to failure resulted in a table of shift factors by pavement type.

Assessment of Pavement Layer Condition with Use of Multiload-Level Falling Weight Deflectometer Deflections

2005 ◽  
Vol 1905 (1) ◽  
pp. 107-116 ◽  
Author(s):  
Hee Mun Park ◽  
Y. Richard Kim ◽  
Seong Wan Park
Keyword(s):  
Damage Index ◽  
Nonlinear Behavior ◽  
Condition Assessment ◽  
Load Level ◽  
Assessment Procedure ◽  
Falling Weight Deflectometer ◽  
Finite Element Program ◽  
Curvature Index ◽  
Stress Dependent ◽  
Falling Weight

A condition assessment procedure for pavement layers that uses multiload-level falling weight deflectometer (FWD) deflections is presented. A dynamic finite element program that incorporates a stress-dependent soil model was used to generate the synthetic deflection database. On the basis of the data in this database, the relationships between surface deflections and critical pavement responses, such as the stresses and strains in each layer, have been established. The FWD deflection data, distress survey results, temperature, and laboratory testing results used to develop this procedure were collected from the Long-Term Pavement Performance project database. Research efforts also focused on the effect of the FWD load level on the condition assessment procedure. The results indicate that the proposed procedure can estimate the asphalt concrete (AC), base, and subgrade layer conditions. The AC layer modulus and the tensile strain at the bottom of the AC layer were found to be better indicators of the condition of the AC layer than the deflection basin parameter. It was also found that the structurally adjusted base damage index and base curvature index were good indicators for prediction of the stiffness characteristics of the aggregate base and subgrade, respectively. An FWD test with a load of 71.2 kN or less does not improve the accuracy of this procedure. The results from the study of the nonlinear behavior of a pavement structure indicate that the deflection ratio obtained from multiload-level deflections can predict the type and quality of the base and subgrade materials.

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