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Primary Topic: Pavement Maintenance
Description: The resilient modulus or stiffness of the soil and rock in the subgrade at a paving project is a critical factor in determining the thickness and composition of the pavement layers. However, measuring the resilient modulus of a particular site has been, at best, a complex and difficult task. The process, as outlined in the 1993 AASHTO Guide for Design of Pavement Structures, calls for the resilient modulus to be measured using a carefully controlled laboratory test on a small sample of the subgrade. Because the laboratory test is complex and can produce inconsistent results, many highway agencies have been hesitant to conduct them.
To address this issue, the Long Term Pavement Performance (LTPP) program developed a standardized laboratory procedure to measure the resilient modulus of subgrade materials, along with a related laboratory startup and calibration verification procedure. This procedure has since been adopted as an American Association of State Highway and Transportation Officials (AASHTO) provisional standard, "Standard Test Method for Determining the Resilient Modulus of Soils and Aggregate Materials."
To help highway agencies understand the new procedure, three videotapes have been produced by FHWA through a cooperative agreement with the Minnesota Department of Transportation. The videotapes explain the how and why of LTPP's revised resilient modulus laboratory tests and procedures.
FHWA Publication Number: FHWA-RD-99-162
Publication Year: 1999
Document Links: PDF (file size: 0.3 mb)
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