INSTRUCTOR: Robert M. Koerner, Ph.D., P.E., D.GE, Dist. M.ASCE

Course Length:  90 minutes

Purpose and Background

Beginning in mid-1930, geotextiles and then geogrids have been used in unpaved and paved roads for the purposes of reduced stone base thicknesses and/or improved serviceability. Today, they are used primarily in four discrete applications. This webinar is subdivided accordingly. First, for use as unpaved road reinforcement, the theory is well developed such that benefit/cost of using geotextiles or geogrids can be assessed. This application is very well positioned and accepted. Second, the webinar reviews paved road stabilization and a number of geogrid design methods focusing on increased trafficability. Also presented is an observational approach to mitigate longitudinal cracks for paved roads under the assumption of lateral reinforcement. Third, for paved roads, geotextiles have been used as separators to keep the crushed stone base course from mixing with the soil subgrade, the theory is not well developed and reliance is on field studies. Fourth, the webinar describes both geotextiles and geogrids insofar as prevention of reflective cracks through asphalt overlays. Both theory and field behavior are presented.

Primary Discussion Topics

• Introduction and Background
• Unpaved Roads Reinforcement With Geotextiles or Geogrids
• Paved Road Applications Using Geogrid Reinforcement
• Paved Road Applications Using Geotextile Separators
• Geotextile and Geogrid Interlayers for Asphalt Overlays
• Summary and Conclusions

Learning Outcomes

• Learn about the four major geosynthetic applications with respect to unpaved and paved roads
• Learn how geotextiles and geogrids are involved depending on exactly where in the roadway cross-section they are placed
• Learn about the quality of the soil subgrade
• Design methodologies
• The relevant test methods and procedures required for input data
• Numeric examples of the required stone or asphalt thicknesses
• What an owner or design consultant can realistically expect for long-term field performance

Webinar Benefits

• Appreciate the very different applications of geotextiles and geogrids insofar as pavements are concerned
• Understand how the soil subgrade, stone base course, and pavement material function vis-à-vis the specific geosynthetic and its location in the cross-section
• Appreciate where design models are fully developed, moderately developed or quite nonexistent
• Understand how laboratory test values of the geosynthetic material are used in the various design processes

Intended Audience

• Federal, state and regional transportation, materials and geotechnical engineers
• Engineers from municipal districts and townships
• Private and municipal owners of all types of unpaved and paved roads
• General engineering consulting engineers
• Soils and geosynthetic testing laboratories servicing these organizations
• Manufacturers and representatives of geotextiles and geogrids
• Contractors and installers servicing these applications
• Academic and research groups
• Others desiring technically related information on this important aspect of our infrastructure system

Webinar Outline

• Introduction and Background
• Unpaved Roads Reinforced With Geotextiles or Geogrids
• Paved Road Applications Using Geogrid Reinforcement
• Paved Road Applications Using Geotextile Separators
• Geotextile and Geogrid Interlayers for Asphalt Overlays
• Summary and Conclusions