Use of Fine Graded Mixes for Pavement Preservation: Workshop Materials (0-6615-P2)

Chip seals are a good way to keep roads sealed, but when this treatment is used close to populated areas, it can create some problems with road noise. Many people have noticed the good performance of a specific type of open graded friction course (OGFC) that is currently used on many low-volume roads in New Mexico. The OGFC is finer and placed significantly thinner than the Texas Department of Transportation's (TxDOT's) porous friction course (PFC) mixes. The typical OGFC in New Mexico is placed at a thickness between ½ inch and ¾ inch. This mix is used as an alternate to seal coat or microsurfacing. The mix is much quieter and smoother than a typical seal coat or microsurfacing. Such a mix could give TxDOT more or better options regarding surfacing low-volume roadways. These workshop materials (student guide, instructor notes, and PowerPoint presentation) present findings on the use of fine graded mixes on low-volume roads. The class sections include:

• Types of very thin overlays (1 inch or less).
• Review of proposed specifications for thin overlays.
• Implementation/evaluation within districts.
• Development of mix designs for a typical district.
• Laboratory measurements of surface noise absorption and skid.
• Performance problems already encountered with thin overlays.