Current ICT Project
Investigators:
  William Buttlar (Primary), Tim Murphy, Bill Pine
Project Title:
  Designing, Producing & Constructing Fine-Graded Hot Mix Asphalt (HMA) on IL Roadways
Start Date: 8/16/2009
End Date: 12/31/2011
Summary of Project:
  A collaborative effort between the University of Illinois at Urbana-Champaign (UIUC), Murphy Pavement Technology (MPT), and Heritage Research Group (HRG), in conjunction with the Illinois Department of Transportation (IDOT) will be conducted. The current C-G gradation limits were originally established based on the view point that C-G HMA is more stable than F-G HMA, which was true in the past due to the use of natural sand only, which produced inappropriate gradations. However, manufactured sand is a common component in HMA today, especially in higher Ndesign mixes. Other states have developed good performing F-G mixtures, which have benefits such as consistency of field compaction to higher density (creating lower permeability) and improved smoothness. Since manufactured sand (e.g., FM20) might not provide sufficient breadth of stockpile material to allow the design of finer gradations with adequate load carrying capacity, other products may need to be produced, including ¼” crushed clear (low minus #200) material, which would provide better aggregate structure and could help to extend the amount of recycled asphalt pavement (RAP) that could be incorporated into the mixture.
Objective of Project:
  This project will assist IDOT in the modification of existing asphalt mixture specifications to allow the use of fine-graded (F-G) hot-mix asphalt (HMA) as an alternative to coarse-graded (C-G) HMA in Illinois for binder, level binder, and/or surface course asphalt pavement layers.
Expected Outcome:
  This study will produce comprehensive laboratory and accelerated pavement data, which will lead to recommendations for the development of a F-G HMA specification for IDOT. Recommendations for new aggregate gradations to support the design of F-G mixtures will also be provided, if deemed necessary.
Click here to check the status of this project.
Last Updated: 10/22/2009