DETERMINATION OF REMAINING FLEXIBLE PAVEMENT LIFE. VOLUME IV. ANALYSIS OF IN-SITU GRANULAR LAYER MODULUS FROM DYNAMIC ROAD RATER DEFLECTIONS

The objective of the study was to investigate the ability of elastic layered theory coupled with non-linear dynamic modulus tests to predict comparable pavement deflections to that measured from dynamic Road Rater deflections. It was found, for over 180 test dates, pavement sections, sensor combinations, that the theoretically predicted deflection over-estimated the measured Road Rater deflections by a factor of about 2 to 4 (2.8 average). In order to obtain equal predicted and measured deflection values, the granular layer non-linear modulus was adjusted by a factor K1. A linear log-log relationship was found when the K1 factor was regressed to the measured surface deflections. It was concluded that the current laboratory method of modulus characterization to incorporate non-linear behavior underestimates the modulus of that granular material. An investigation was undertaken to determine whether the effect of shear strain was responsible for the decrease in granular layer modulus. It was found that the modulus does decrease with increasing shear strain and shear strain is proportional to surface deflection. These results indicated that relationships between surface deflection, shear strain, and granular layer modulus can be applied to predict in-situ modulus from deflection measurements.

• Supplemental Notes:
  • See also Volume 3, PB-296564. Prepared for Maryland State Highway Administration, Brooklandville. Also available in set of 4 reports, PB-296561-SET.
• Corporate Authors:

  University of Maryland, College Park

  Department of Civil and Environmental Engineering
  College Park, MD  United States  20742

  Maryland Department of Transportation

  State Highway Administration, 2323 West Joppa Road
  Brooklandville, MD  United States  21022

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Witczak, M W
  • D'Amato, P A
• Publication Date: 1978-10

Media Info

• Pagination: 265 p.

Subject/Index Terms

• TRT Terms: Deflection; Deterioration; Dynamic modulus of elasticity; Dynamic tests; Failure; Field tests; Flexible pavements; Forecasting; Granular bases; Maintenance; Mechanical fatigue; Pavements; Performance tests; Service life; Shear strain; Shear stress
• Uncontrolled Terms: Field measurements
• Geographic Terms: Maryland
• Old TRIS Terms: Pavement deflection; Pavement life
• Subject Areas: Design; Highways; Maintenance and Preservation; Pavements;

Filing Info

• Accession Number: 00197624
• Record Type: Publication
• Source Agency: National Technical Information Service
• Report/Paper Numbers: FHWA/MD/R-79/4 Final Rpt.
• Files: NTIS, TRIS, USDOT, STATEDOT
• Created Date: Aug 28 1979 12:00AM