THE BAILEY METHOD OF GRADATION EVALUATION: THE INFLUENCE OF AGGREGATE GRADATION AND PACKING CHARACTERISTICS ON VOIDS IN THE MINERAL AGGREGATE (WITH DISCUSSION)

Aggregate type and gradation are routinely considered in hot mix asphalt design. Mix designers learn by experience the combination of aggregates that will provide adequate voids in the mineral aggregate. Adequate rules or laws that govern the effect of gradation on aggregate packing are not available to mix designers. In this paper a method of gradation analysis, called the Bailey method, is presented that takes into consideration the packing characteristics of individual aggregates and provides quantified criteria that can be used to adjust the packing characteristics of a blend of materials. An experiment is reported that varied the aggregate gradation criteria in the Bailey method and demonstrated the response of aggregate packing to the criteria.