Influence of Base Clearance on Subgrade Resilient Modulus of Florida Roadway Pavements

The resilient modulus of pavement subgrade materials is an essential parameter for mechanistically based flexible pavement design procedures. “Base clearance” is defined as the clearance between the groundwater level and the pavement base layer within a pavement system. A high pavement moisture content, which is strongly influenced by the base clearance, causes detrimental effects on the resilient modulus of pavement subgrades. The determination of a pavement base clearance is one of the most important steps toward setting up grade lines in a roadway design. This paper presents an experimental study to evaluate the effects of base clearance on the resilient modulus of pavement subgrades. Full-scale dynamic pavement tests were conducted in test pits to simulate vehicle dynamic impact on field pavements. The level of base clearance was adjusted by raising or lowering the water level within the pavement layer in the pit. Ten types of Florida subgrade material were tested at different base clearances for this study. The dynamic plate load test results were compared with the resilient modulus obtained from the laboratory triaxial test by using layer theory. The differences between the resilient modulus from the laboratory test and the plate load test were typically about 20%. Resilient modulus measured from the laboratory triaxial test could be used to predict the resilient deformation of the pavement subgrade layers. The experimental results showed that, at lower base clearances, the high pavement moisture content caused a significant reduction of the resilient modulus of pavement subgrade layers. The resilient modulus of subgrade materials decreases with the decrease of base clearance.


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  • Accession Number: 01157790
  • Record Type: Publication
  • ISBN: 9780309142946
  • Report/Paper Numbers: 10-2815
  • Files: TRIS, TRB, ATRI
  • Created Date: Jan 25 2010 11:22AM