EVALUATION OF PAM BASE CRACK CONTROL

Illinois Department of Transportation policies permit threee types of stabilized base courses for flexible pavements. In Chicago, pozzolanic aggregate mixtures (PAM) are cheaper than bituminous- and cement-stabilized mixes. As a result, many of the reconstruction projects in that area are being built with PAM as the base course material. The PAM base course gains its strength through chemical reactions very similar to those characterizing Portland cement concrete. During this process, moisture is depleted, the mixture shrinks, and shrinkage cracks occur. These shrinkage cracks inevitably reflect thrrogh the bituminous surface. To combat this problem, Illinois borrowed a technique used by Portland cement concrete pavers. Joints were cut in the newly placed PAM base course to control the location of the shrinkage cracks and, hence, the reflection cracks. Several joint designs and joint spacings were evaluated. This paper describes the project, summarizes its cost, and evaluates its effectiveness. (Author)

• Corporate Authors:

  Illinois Department of Transportation

  Bureau of Materials and Physical Research
  126 East Ash Street
  Springfield, IL  United States  62704-4766

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Traylor Jr, M L
  • Lippert, D
• Publication Date: 1984-12

Media Info

• Features: Figures; Tables;
• Pagination: 7 p.

Subject/Index Terms

• TRT Terms: Control; Cracking; Flexible pavements; Joints; Pavement base course; Pozzolan; Reflection cracking; Shrinkage; Stabilized materials
• Old TRIS Terms: Joint; Shrinkage cracks
• Subject Areas: Construction; Design; Geotechnology; Highways; Pavements; I22: Design of Pavements, Railways and Guideways;

Filing Info

• Accession Number: 00396672
• Record Type: Publication
• Report/Paper Numbers: FHWA/IL/PR-098 Intrm Rpt., Physical Res 98
• Contract Numbers: IHR-513
• Files: TRIS, USDOT, STATEDOT
• Created Date: Mar 31 1986 12:00AM