Details:

Alternative Title:
Investigation of the use of resilient modulus for Louisiana soils in the design of pavements.
Creators:
Mohammad, Louay N. ; Puppala, Anand J.
Mohammad, Louay N. ; Puppala, Anand J. Less -
Corporate Creators:
Louisiana Transportation Research Center
Corporate Contributors:
United States. Federal Highway Administration
Subject/TRT Terms:
[+]
California Bearing Ratio Clay Dynamic Materials Characterization Dynamic Tests Flexible Pavements Measurement Modulus Of Resilience Moisture Content Pavement Design Resilient Modulus Sand Soils Stresses Triaxial Shear Tests Triaxial Testing
Publication/ Report Number:
FHWA/LA-94/283
Resource Type:
Tech Report
Geographical Coverage:
Louisiana
Corporate Publisher:
Louisiana Transportation Research Center
Abstract:
The 1986 AASHTO Guide for the Design of Pavement Structures has adopted the use of resilient modulus (M,) as a fundamental proponent to characterize flexible pavement materials. The resilient modulus is defmed as the ratio of the repeated axial deviatoric stress to the recoverable axial strain. The Louisiana Department of Transportation and Development, like many other state transportation agencies, has started implementing the AASHTO design procedure. At present, there are several types of dynamic testing devices which can be used to measure the resilient modulus. The repeated load triaxial test device is the most popular one because of the repeatability of the test results. In addition, it also allows the incorporation of field stresses.

A research study was initiated to develop a laboratory test procedure to characterize subgrade soils based on the structual properties obtained from repeated load triaxial testing. The objectives of this study were: (1) to develop a method for determination of the resilient modulus of Louisiana soil: (2) to evaluate the influence of using two separate internal measurement systems on the resilient modulus test results; (3) to provide a preliminary estimate of resilient modulus from physical properties of soil and (4) to compare laboratory determined resilient modulus with the one determined from field nondestructive deflection data. A statistically designed test factorial was used to examine the influence of the measurement system and AASHTO testing procedure on the resilient modulus test results. Two in-cell axial deformation measurement systems (one at the ends and the other one at the middle one-third of the specimen height), two AASHTO test procedures, T-292 and T-294, and two soil types (cohesive and granular) were used. In addition, this study examined the influence of moisture content and dry density variation on the test results. Three levels of moisture content and dry density were used in both cohesive and granular soils.

The results of the rest program indicated that both measurement systems and testing procedures provided repeatable results. The resilient modulus of sands and silty clays determined from the middle measurement system is significantly different from that determined from the end measurement system. The resilient modulus of sands obtained from T-292 procedure is significantly different from those obtained from T-294 procedure. The influence of testing procedure and measurement systems on resilient modulus results is presented in the form of normalized factors. These factors are discussed with respect to confining stress, deviatoric stress, moisture content and dry densities. Resilient modulus prediction models using bulk stress and deviatoric stress are evaluated for the soil types tested. The influence of testing procedures, measurement systems and moisture content variations on the regression model constants are presented. Preliminary comparisons between laboratory determined resilient moduli and resilient moduli computed from field nondestructive methods showed that field methods predict lower values of resilient properties.


Format:
PDF
Funding:
92-2GT
Collection(s):
US Transportation Collection
Main Document Checksum:
[+]
urn:sha256:26528544fb179f51e9a1f47b38c48dbc2a1491cbe857c9e1b9ac7dad97f7fcec
Download URL:
https://rosap.ntl.bts.gov/view/dot/22250/dot_22250_DS1.pdf
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