Texas A&M Transportation Institute

FHWA/TX-15/0-6686-2

Tech Report

Texas

Texas A&M Transportation Institute

Limestone Rock Asphalt (LRA) mixtures have been produced and placed for several decades using specification requirements currently listed under DMS 9210. Several districts have had placement issues and premature failures at the beginning of 2010. These issues and failures have been attributed to material properties. Requirements for DMS 9210 have not changed for several years and need to be evaluated to possibly produce a higher quality material to reduce the occurrence of premature failures and to minimize placement issues. The objectives of the study are to (1) evaluate specification requirements of Item 330 and DMS 9210, (2) conduct field evaluations and lab testing to determine workability and acceptability as stockpile material for use as needed in pavement maintenance, and (3) consider improvements to the specification requirements to ensure an acceptable and workable stockpile material for up to 6 months. The Hveem stability was determined to be a good indicator of rutting resistance of LRA but it does not indicate when a mix is too dry and susceptible to raveling. The Cantabro test was able to identify dry mixtures with insufficient flux oil as well as poor quality flux oil. A Cantabro loss of 15 percent maximum is being proposed as a new specification test and limit

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Project 0-6686

US Transportation Collection