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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. - PowerPoint PPT Presentation
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High Value Research Session:High Value Research Session:
Allison R. HardtAllison R. HardtOffice of Policy and ResearchOffice of Policy and Research
Maryland State Highway AdministrationMaryland State Highway Administration
RAC Annual MeetingRAC Annual MeetingJuly, 2011July, 2011
Evaluation of Laboratory Tests to Quantify Evaluation of Laboratory Tests to Quantify Frictional Properties of AggregatesFrictional Properties of Aggregates
Evaluation of Laboratory Tests to Quantify Evaluation of Laboratory Tests to Quantify Frictional Properties of AggregatesFrictional Properties of Aggregates
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Background:Background:
A vital component of safe highways is the friction A vital component of safe highways is the friction characteristics of the pavement surface. characteristics of the pavement surface.
The coarse aggregate used in hot-mix asphalt (HMA) The coarse aggregate used in hot-mix asphalt (HMA) pavements plays an important role in development of pavements plays an important role in development of surface friction. surface friction.
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Evaluation of Laboratory Tests to Quantify Evaluation of Laboratory Tests to Quantify Frictional Properties of AggregatesFrictional Properties of Aggregates
Problem:Problem:
In 2006 the long standing method used by SHA to In 2006 the long standing method used by SHA to evaluate the ability of coarse aggregates to provide evaluate the ability of coarse aggregates to provide high friction in HMA pavements was showing its age high friction in HMA pavements was showing its age and used very old equipment. and used very old equipment.
It was determined that SHA needed to identify a It was determined that SHA needed to identify a better method to perform this critical test procedure.better method to perform this critical test procedure.
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Evaluation of Laboratory Tests to Quantify Evaluation of Laboratory Tests to Quantify Frictional Properties of AggregatesFrictional Properties of Aggregates
Objective:Objective:
The objective of the project was to update the The objective of the project was to update the friction evaluation portion of SHA’s aggregate friction evaluation portion of SHA’s aggregate specifications. specifications.
Evaluation of Laboratory Tests to Quantify Evaluation of Laboratory Tests to Quantify Frictional Properties of AggregatesFrictional Properties of Aggregates
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Description:Description:
Phase 1:Phase 1:
1.1. Identify test procedures used by other DOTs Identify test procedures used by other DOTs that show promise in determining aggregate that show promise in determining aggregate friction properties. friction properties.
2.2. Determine whether to pursue replacement of Determine whether to pursue replacement of existing evaluation method with new test existing evaluation method with new test equipment and procedures. equipment and procedures.
Evaluation of Laboratory Tests to Quantify Evaluation of Laboratory Tests to Quantify Frictional Properties of AggregatesFrictional Properties of Aggregates
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Description:Description:
Phase 2:Phase 2:
1.1. Develop a revised aggregate acceptance Develop a revised aggregate acceptance procedure.procedure.
2.2. Conduct a variability study and establish new test Conduct a variability study and establish new test procedures for the British Wheel/Pendulum procedures for the British Wheel/Pendulum Tester.Tester.
3.3. Procure the National Center for Asphalt Procure the National Center for Asphalt Technology (NCAT) Polisher and Dynamic Friction Technology (NCAT) Polisher and Dynamic Friction Tester and develop test procedures and Tester and develop test procedures and specifications. specifications.
Evaluation of Laboratory Tests to Quantify Evaluation of Laboratory Tests to Quantify Frictional Properties of AggregatesFrictional Properties of Aggregates
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Results:Results:
A draft aggregate acceptance specification A draft aggregate acceptance specification was developed.was developed.
A new test procedure for the British A new test procedure for the British Wheel/Pendulum was developed.Wheel/Pendulum was developed.
New polishing test equipment was procured New polishing test equipment was procured and implemented.and implemented.
New test procedures were developed.New test procedures were developed.
Evaluation of Laboratory Tests to Quantify Evaluation of Laboratory Tests to Quantify Frictional Properties of AggregatesFrictional Properties of Aggregates
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Benefit:Benefit:
SHA has a new and modern method for SHA has a new and modern method for testing coarse aggregates for susceptibility to testing coarse aggregates for susceptibility to polish under traffic. polish under traffic.
In this photo: In this photo: Picture of the NCAT Picture of the NCAT polisher with specimen in placepolisher with specimen in place
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Contact InformationContact Information
Allison HardtAllison Hardt
Chief, Research DivisionChief, Research Division
Office of Policy and Research Office of Policy and Research
Maryland State Highway Administration Maryland State Highway Administration
707 N. Calvert St. 707 N. Calvert St.
Baltimore, Maryland 21202 Baltimore, Maryland 21202
410-545-2916 410-545-2916
