FHWA/IN/JTRP-2000/28 Final Report DEVELOPMENT OF A PROCEDURE TO IDENTIFY AGGREGATES FOR BITUMINOUS SURFACES IN INDIANA

The contents of this report reflect the views of the authors, who are responsible for the facts and the accuracy of the data herein. The contents do not necessarily reflect the official views or policies of the Indiana Department of Transportation or the Federal Highway Administration at the time of publication. This report does not constitute a standard, specification or regulation. Adequate friction resistance is needed to prevent pavement slipperiness allowing vehicles to stop in a reasonable distance. For stone mastic asphalt surfaces, friction resistance is mainly a function of the interaction between the aggregates exposed at the road surface and vehicle tires. Aggregate performance is reduced with time by wear and polishing as a consequence of vehicular traffic. In this research a method to investigate performance based on physical, chemical and petrographic factors has been evaluated. The objective was to develop a laboratory method to test Indiana dolomite, limestone, sandstone, and gravel aggregates to predict friction resistance in the field and determine causes for the range of values among these aggregates. Assessment of gravel sources was based on individual rock types and their proportions comprising the gravel. Initial friction Values (IFV) and Polished Values (PV) were determined in the laboratory with the British Wheel and Pendulum test and field values obtained from the towed friction trailer. For two laboratories involved a significant difference in IFV and PV was obtained so that further verification is required. Correlations between parameters were established which provide predictions of friction resistance based on laboratory specimens. A database of physical and chemical properties should be collected on aggregates used or considered for bituminous wearing courses. This includes the testing required for Class A aggregates plus elemental Mg and elemental Ca content. Introduction Adequate friction resistance is needed to prevent pavement slipperiness allowing vehicles to stop in a reasonable distance. For stone mastic asphalt surfaces, friction resistance is mainly a function of the interaction between the aggregates exposed at the road surface and vehicle tires. Aggregate performance is reduced with time by wear and polishing as a consequence of vehicular traffic. In this research a method to investigate performance based on physical, chemical and petrographic factors has been evaluated. The objective was to develop a laboratory method to test Indiana dolomite, limestone, sandstone, and gravel aggregates to predict friction resistance in the field and determine causes for the range of values among these aggregates. Assessment of …