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.

Essentially, the “Bailey Method of Gradation Selection” is a tool for developing and analyzing blend gradations in the lab and field. It gives designers and contractors a better appreciation of aggregate packing and its influence on mix volumetrics and compactibility. The method includes guidelines for evaluating aggregates and the aggregate blend by volume, as well as by weight, and makes provision for the use of Reclaimed Asphalt Pavement (RAP).

The focus of the Bailey method is aggregate packing. In order to better understand aggregate packing, we need to determine what particles form the coarse aggregate structure and which ones fit into the voids created within that structure.

The Bailey Method applies to coarse-graded, fine-graded and SMA mixtures. The method can help explain why some Superpave mixes are difficult to compact . It also provides insight as to why small gradation changes, which often occur during production and are within allowable tolerances, can cause significant changes to mixture volumetric properties and/or field compactibility.


To register for a Bailey Method Course click the links below:

Testimonials from attendees
“To sum it all up in numbers, in 2005, we lost around $250,000 in deducts for Voids, VMA, and Compaction.  To date in 2006, using the Bailey Method, we are up $300,000 in incentives.  To make this an even greater accomplishment, we achieved this incentive on half the jobs we had last year with incentive.  What makes it even more incredible is the fact that there were two incidents that if the super would have called me sooner, I could have fixed the problem and kept from losing $55,000 in deducts.”
– QA Manager for a large regional Contractor after attending the full 3-Day Course at Asphalt Institute Headquarters

“My bosses will see this class pay for itself the first week of the paving season.”

“I’ve learned more about adjusting VMA in this course than I have learned in the last 28 years.”

“Been doing mix designs for 15 yrs and this class confirmed 95% of what I believed to be true and set me straight on the other 5%.”

“Using the Bailey Method, we are up $300,000 in incentives…on half the jobs we had last year with incentives.”