Bailey Method - Achieving Volumetrics and HMA Compactability

After decades of use, we have gained a lot of valuable experience with the Marshall mix design method. Accordingly there is a degree of comfort in working with the Marshall method in designing mixes. While there has been some guidance on the use of coarse and fine Superpave mixes, at this time, designers are still struggling with mix designs and have to conduct numerous trials to select the proper aggregate blend. A better way to speed up the process and understand the mixes that are being produced is needed. The Bailey method was originally developed by Robert D. Bailey of the Illinois Department of Transportation in the early 1980s. It is a practical tool that has been successfully utilized for developing and analyzing hot asphalt mixes in the lab and field. The Bailey method provides a good starting point for mix design and an invaluable aid when making adjustments at the plant to improve air voids, VMA and the overall workability of the mix, whether you are using Marshall or Superpave. The paper describes the methodology in detail with some real life examples to help mix designers and contractors better understand the mixes that are currently being used across Canada.