Surface Pavement Solutions for Poor Subgrade Conditions

The western and northern parts of Districts 4 and 6 in South Florida have shallow layers of organic and plastic soils under existing roads. These roads often exhibit large amount of cracking and distortion in a short period of time. Traditional repairs are often not practical due to high costs and extended construction time, as they require complete reconstruction of the roads with surcharge or removal of the unsuitable soils materials. The use of geosynthetic reinforcements at the base/subgrade interface are not "surface" solutions, as they require removal of the pavement and base. Therefore, the primary motivation behind the current study as to identify rehabilitation strategies which could be readily applied to the asphalt surface layers, and to develop design methodology based on some site-specific conditions so that the identified techniques could be used elsewhere if similar soil conditions are encountered. For that purpose, a 6-mi long Pilot Test Site was selected along the alignment of SR 15 / US 98 in northwest Palm Beach county, where severe pavement distresses were observed due to the existence of thick organic layers, and a reconstruction project was scheduled to begin in 2007. Following tasks were accomplished in this study: (i) Piezocone Penetration Tests (CPTu) with Porewater Dissipation Experiments were conducted at nine locations for rapid oil-site evaluation of the strength and compressibility of Florida organic soils and peats; (ii) A concurrent laboratory consolidation and secondary compression test program were conducted to validate the field test results; (iii) The site-specific soil conditions (moisture content, organic content, thickness and unit weight of the organic layer) were expressed by an Organic Factor (F sub org), which as correlated with pertinent soil properties, mechanistic pavement response parameters, and probable pavement performance; (iv) PaveTrac MT-I, GlasGrid 8501, and PetroGrid 4582 were recommended as promising asphalt reinforcing products to be incorporated in experimental pavement sections proposed at 2 different locations with different Organic Factors (F sub org) in order to develop direct correlations between F sub org and pavement performance, and also to facilitate relative comparisons of the candidate solutions; and (v) A conceptual design framework as developed linking laboratory/field investigations, site-specific parameters, mechanistic analysis, and transfer functions for the prediction of pavement life, so that an appropriate strategy can be adopted in future reconstruction projects.


  • English

Media Info

  • Media Type: Print
  • Edition: Final Report
  • Features: Appendices; Figures; Maps; Photos; References; Tables;
  • Pagination: 163p

Subject/Index Terms

Filing Info

  • Accession Number: 01045433
  • Record Type: Publication
  • Contract Numbers: BD-546, RPWO#4
  • Created Date: Mar 27 2007 7:49PM