Subgrade Resilient Modulus Testing at Tennessee Instrumented Pavement Sites
Author | : Jason Ernest Cathey |
Publisher | : |
Total Pages | : 400 |
Release | : 2001 |
Genre | : Pavements |
ISBN | : |
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Author | : Jason Ernest Cathey |
Publisher | : |
Total Pages | : 400 |
Release | : 2001 |
Genre | : Pavements |
ISBN | : |
Author | : Shiraz D. Tayabji |
Publisher | : ASTM International |
Total Pages | : 534 |
Release | : 2000 |
Genre | : Materials |
ISBN | : 0803128584 |
As with the previous two symposia, the 32 papers from the June/July, 1999, Seattle symposium present advances in the nondestructive testing of pavements using conventional falling weight deflectometer techniques and other promising techniques such as ground penetrating radar, rolling weight deflecto
Author | : Baoshan Huang |
Publisher | : |
Total Pages | : 322 |
Release | : 2006 |
Genre | : Technology & Engineering |
ISBN | : |
GSP 154 contains 36 papers describing the latest advances in pavement mechanics and performance that were presented at sessions of the GeoShanghai Conference, held in Shanghai, China, June 6-8, 2006.
Author | : |
Publisher | : |
Total Pages | : |
Release | : 2003 |
Genre | : |
ISBN | : |
Flexible Pavement is usually composed of several asphalt concrete layers, a granular base course and a soil subgrade. For mechanistic design of pavement systems based on elastic theory a modulus of elasticity must be designated for each design layer including the soil subgrade. The resilient modulus is used to characterize the soil in pavement design. The resilient modulus is defined as [equation] Where [symbol] is the deviator stress or the difference between the axial and confining stress, and [symbol] is the recoverable axial strain. The standard procedure for obtaining [symbol] is a repeated load tri-axial test at a constant confining pressure. There is not a singular resilient modulus value for a particular soil but rather the modulus is a function of the stress state. The standard test produces a range of resilient modulus values in a series of stress conditions. The resilient modulus test is inherently complicated, time consuming, and expensive. For these reasons, most commercial and design laboratories will not conduct these tests but instead rely on empirical relationships. Therefore, it has been recommended that alternative tests be developed to approximate resilient modulus. The Alternative Test Method was developed to be a simple and effective way of determining resilient modulus. The ATM design was based on a single degree of freedom, lumped mass spring system in which a hammer of known mass falls onto a volume of soil. Originally, there appeared to be good correlation between the Alternative Test Method and the standard test method for obtaining resilient modulus. However, subsequent testing failed to produce consistent results or confirm the correlation. Improvements have been made to the ATM to improve the overall consistency of results and correlation with the standard resilient modulus test results. The improvements to the ATM device include a new, more consistent drop mechanism, better data acquisition software, and a new calculation method. ATM tests were conducted on 4 different soils from TDOT research sites. Standard tri-axial resilient modulus tests were conducted for comparison with ATM resilient modulus tests. The improved ATM appears to measure a material response that correlates reasonably well with the standard triaxial resilient modulus test results for those soils tested. Furthermore, the Improved ATM produces much more consistent results than the Original ATM. It is also believed that the limitations of the device are outweighed by its simplicity and commonality with other lab tests. Therefore, the improved Alternative Test Method for resilient modulus of fine grained soils is believed to be a viable alternative to the standard test method for obtaining resilient modulus values.
Author | : Daniel K. Hellrung |
Publisher | : |
Total Pages | : 103 |
Release | : 2015 |
Genre | : Pavements |
ISBN | : 9781321892161 |
In an effort to build more cost effective and robust pavement structures, the Wyoming Department of Transportation (WYDOT) is in the transition of adopting the Mechanistic-Empirical Pavement Design Guide (MEPDG) instead of the 1993 AASHTO Pavement Design Guide. The University of Wyoming is currently conducting a comprehensive research study to facilitate the implementation of the MEPDG in the state. This thesis describes using a Falling Weight Deflectometer (FWD) as a non-destructive testing method for data collection and the development of a back-calculation testing protocol for estimating the resilient modulus of subgrade soils in Wyoming. During the summer of 2013, FWD testing was performed at 32 test sites throughout the state of Wyoming. Deflection measurements were collected and used to back-calculate the resilient modulus of the subgrade at each test site. The back-calculation protocol was developed by modifying the user guide of MODTAG, a back-calculation software, to achieve consistent and realistic back-calculated modulus results. Additionally, using these back-calculation results and laboratory measured modulus results for the same test site, two linear regression models were developed to correct the back-calculation results to laboratory equivalent values. The sum of square error (SSE) was used to compare the models and then select the most suitable one. The findings of this research will facilitate the MEPDG calibration which will help with the implementation of the MEPDG in the state of Wyoming.
Author | : Mark Raulston Madgett |
Publisher | : |
Total Pages | : 310 |
Release | : 1994 |
Genre | : Pavements |
ISBN | : |
Author | : California. Office of Transportation Laboratory |
Publisher | : |
Total Pages | : 42 |
Release | : 1974 |
Genre | : Soil mechanics |
ISBN | : |
Author | : Zachary R. Henrichs |
Publisher | : |
Total Pages | : 319 |
Release | : 2015 |
Genre | : Pavements |
ISBN | : 9781321982947 |
To improve the pavement design and construction in Wyoming, the Wyoming Department of Transportation (WYDOT) is adopting the Mechanistic-Empirical Pavement Design Guide (MEPDG). Calibration of local subgrade materials are needed to implement the MEPDG. This thesis describes the measurement of resilient modulus (Mr) of subgrade materials and prepares a catalog of representative subgrade properties. As part of the comprehensive testing program, subgrade soil samples were collected from 12 locations throughout the state for standard laboratory tests and Mr test. A testing protocol for Mr was developed by modifying the AASHTO Designation: T-307 to incorporate WYDOT practices. Test results show that Mr changes with axial loads, confining pressures, soil types, and depths beneath the pavement. Regression models were developed using statistical methods and design charts were established for estimating Mr-values. The outcomes of this research will facilitate the full implementation of the MEPDG in the state of Wyoming.