DESIGN AND CONSTRUCTION OF MULTIPLE SEAL COATS. FINAL REPORT

The primary objectives of this study were to establish design and construction guidelines for multiple seal coats for the Texas State Department of Highways and Public Transportation. A multiple seal coat is a bituminous surface that results from two or more successive alternating applications of bituminous binder and cover aggregate to an existing paved surface, usually with the smaller aggregate sizes used in each successive layer. From a thorough review of the literature, it was concluded that the key to executing an effective design for multiple seal coats was in the ability to measure the available void space in multiple stone layers that could be filled with binder. A design method developed by the NITRR of South Africa which included a test procedure (Modified Tray Test) for measuring the void content and effective thickness of a stone layer was chosen for further field and laboratory investigation. Based on a statistical analysis of a number of samples, the Modified Tray Test was found to be repeatable. It was also determined that a single sample of stone, as tested by means of the Modified Tray Test, gives a good indication of the overall void content and effective layer thickness for a particular type and grade of stone. The Modified Tray Test was also used to determine the void content and effective layer thickness of double seals made up of different combinations of four aggregate grades. A relationship was found between the effective layer thickness of a double seal and the sum of the bottom and top layers separately. The design method was tested by fabricating multiple seal coats in the laboratory and field and, with modifications, was found to produce satisfactory performance.

• Supplemental Notes:
  • Research study title: Multiple Seal Coat Design and Construction.
• Corporate Authors:

  Texas Transportation Institute

  Texas A&M University System, 1600 E Lamar Boulevard
  Arlington, TX  United States  76011

  Texas State Department of Highways & Public Transportation

  Transportation Planning Division, P.O. Box 5051
  Austin, TX  United States  78763

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Estakhri, C K
  • Gonzalez, M A
• Publication Date: 1988-11

Media Info

• Features: Appendices; Figures; Photos; References; Tables;
• Pagination: 176 p.

Subject/Index Terms

• TRT Terms: Air voids; Design methods; Field tests; Laboratory tests; Performance evaluations; Seal coats; Thickness
• Old TRIS Terms: Air voids content; Multiple layers
• Subject Areas: Design; Highways; Pavements; I22: Design of Pavements, Railways and Guideways; I23: Properties of Road Surfaces;

Filing Info

• Accession Number: 00491891
• Record Type: Publication
• Report/Paper Numbers: FHWA/TX-88/448-1F, Res Rept 448-1F, TTI: 2-9-85-448-1F
• Contract Numbers: Study 2-9-85-448
• Files: TRIS, USDOT, STATEDOT
• Created Date: Mar 31 1990 12:00AM