INFLUENCE OF MIX DESIGN VARIABLES ON INITIAL SURFACE FRICTION OF BITUMINOUS CONCRETE. FINAL REPORT

A series of factorial experiments were performed for laboratory study of initial surface friction of bituminous surfaces as a function of mix design variables: aggregate type, asphalt content and aggregate gradation. British Pendulum Number (BPN) was the dependent variable in all cases. Certain interactions among mix design parameters were found to be very significant, and not capable of being predicted by superimposing the known effects on BPN of single mix design variables. Such interactions as that between percent asphalt and percent aggregate passing the number 200 sieve are non-linear and consequently non-additive, apparently the results of complicated physical or chemical processes. The importance of the finest aggregate size fractions stood out clearly in all experimental results. Microtexture provided by this fine material is especially important at the relatively low speeds characteristic of secondary roads and urban streets. In general, high initial skid resistance is promoted by adhering to the "fine" side of the ODOT 404 gradation limits, especially for material passing the No. 50 sieve. This rule applies to both gravel and limestone aggregate, but mixtures made with limestone are substantially more sensitive to changes in aggregate gradation and exhibit generally more complex behavior than gravel mixed with respect to BPN.

• Corporate Authors:

  University of Toledo

  Department of Civil Engineering, 2801 West Bancroft Street
  Toledo, OH  United States  43606-3390

  Ohio Department of Transportation

  P.O. Box 889
  Columbus, OH  United States  43215

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Colony, D C
• Publication Date: 1987-10

Media Info

• Features: Appendices; Figures; References; Tables;
• Pagination: 164 p.

Subject/Index Terms

• TRT Terms: Aggregate gradation; Aggregates; Asphalt concrete; Asphalt content; Friction; Gravel; Laboratory tests; Limestone aggregates; Microtexture; Mix design; Secondary roads; Skid resistance; Streets; Traffic speed
• Uncontrolled Terms: Low speed
• Old TRIS Terms: Aggregate characteristics; British pendulum number; Local street
• Subject Areas: Geotechnology; Highways; Materials; Pavements; I23: Properties of Road Surfaces; I31: Bituminous Binders and Materials;

Filing Info

• Accession Number: 00467831
• Record Type: Publication
• Report/Paper Numbers: FHWA/OH-88/001
• Contract Numbers: State Job 14411(0)
• Files: TRIS, USDOT, STATEDOT
• Created Date: Mar 31 1988 12:00AM