Texas A&M Transportation Institute

United States. Federal Highway Administration

FHWA/TX-13/0-6621

Tech Report

Texas

Texas. Dept. of Transportation. Research and Technology Implementation Office

The Texas Department of Transportation (TxDOT) currently uses Item 247 “Flexible Base” to specify a

pavement foundation course. The goal of this project was to evaluate the current method of base course

acceptance and investigate methods to replace materials approval based on stockpile sampling and testing

with a mixture design methodology and quality control procedure. Researchers gathered existing information

that would assist in defining the types of tests to be used, specification acceptance criteria, and acceptance

limits. Researchers then gathered data to identify tests that should be considered for inclusion in the

specification and defined property variability of base course materials from nine pits/quarries in Texas. They

also conducted other activities concerning precision and bias statement development, production/placement

variability, technician certification, laboratory accreditation, and the development of relationships that allow

test property parameters to predict pavement performance. The project developed draft flexible base course

specifications in a quality control/quality assurance and quality monitoring program format. Researchers

recommend an implementation project to determine the accuracy of the developed pavement performance

prediction techniques and the suitability of the specification, including the types and limits of the test

parameters in the specification.

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Project 0-6621

US Transportation Collection