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High Value Research Session:

Evaluation of Laboratory Tests to Quantify Frictional Properties of Aggregates. High Value Research Session:. Allison R. Hardt Office of Policy and Research Maryland State Highway Administration RAC Annual Meeting July, 2011.

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High Value Research Session:

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  1. Evaluation of Laboratory Tests to Quantify Frictional Properties of Aggregates High Value Research Session: Allison R. Hardt Office of Policy and Research Maryland State Highway Administration RAC Annual Meeting July, 2011

  2. Evaluation of Laboratory Tests to Quantify Frictional Properties of Aggregates • Background: • A vital component of safe highways is the friction characteristics of the pavement surface. • The coarse aggregate used in hot-mix asphalt (HMA) pavements plays an important role in development of surface friction.

  3. Evaluation of Laboratory Tests to Quantify Frictional Properties of Aggregates • Problem: • In 2006 the long standing method used by SHA to evaluate the ability of coarse aggregates to provide high friction in HMA pavements was showing its age and used very old equipment. • It was determined that SHA needed to identify a better method to perform this critical test procedure.

  4. Evaluation of Laboratory Tests to Quantify Frictional Properties of Aggregates • Objective: • The objective of the project was to update the friction evaluation portion of SHA’s aggregate specifications.

  5. Evaluation of Laboratory Tests to Quantify Frictional Properties of Aggregates • Description: • Phase 1: • Identify test procedures used by other DOTs that show promise in determining aggregate friction properties. • Determine whether to pursue replacement of existing evaluation method with new test equipment and procedures.

  6. Evaluation of Laboratory Tests to Quantify Frictional Properties of Aggregates • Description: • Phase 2: • Develop a revised aggregate acceptance procedure. • Conduct a variability study and establish new test procedures for the British Wheel/Pendulum Tester. • Procure the National Center for Asphalt Technology (NCAT) Polisher and Dynamic Friction Tester and develop test procedures and specifications.

  7. Evaluation of Laboratory Tests to Quantify Frictional Properties of Aggregates • Results: • A draft aggregate acceptance specification was developed. • A new test procedure for the British Wheel/Pendulum was developed. • New polishing test equipment was procured and implemented. • New test procedures were developed.

  8. Evaluation of Laboratory Tests to Quantify Frictional Properties of Aggregates • Benefit: • SHA has a new and modern method for testing coarse aggregates for susceptibility to polish under traffic. In this photo: Picture of the NCAT polisher with specimen in place

  9. Contact Information Allison Hardt Chief, Research Division Office of Policy and Research Maryland State Highway Administration 707 N. Calvert St. Baltimore, Maryland 21202 410-545-2916 ahardt@sha.state.md.us

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