New Developments for Geogrid Reinforced Base Courses

The reinforcing properties (e.g. bars, straps, filaments), the geogrid properties, the thickness of the soil or the soil type and the durability properties of a geogrid greatly influence the construction project scope, design, product selection and expected service life in a road construction. When a geogrid is inserted into a base course layer, there are several properties which affect the long-term performance of the design. It is not only a single property such as the stiffness and strength of a geogrid. At the end the integrity of the installation needs to be protected in all directions. Therefore even if the general application of a geogrid in a base course sounds simple it is a complex summary of properties which work hand in hand. This paper will list mechanical properties of geogrids used in base courses of flexible pavements, which are currently considered to provide benefit for the performance of this composite layer. Furthermore a new design method for geosynthetic reinforced flexible pavements, the so called mechanistic-empirical design method will be described and experimental results for a laid and welded geogrid and geocomposite will be presented. The results will finally be compared to the Giroud & Noiray (1981) design method.