Index and Performance Testing a New Geogrid Made of Highly Oriented Straps

A new geogrid made of separate straps, welded together at the connections using a laser welding technique has been developed after years of intensive research. The newly developed and patented welding system is described in this paper. It allows the highly stretched and oriented straps to be welded together without losing the orientation of the molecules in the welded area. This is very important because otherwise a change of material properties will occur which will influence the long term strength and creep of the material. Further it results in very efficient use of material and therefore in a cost-effective material. The new geogrid combines the strong properties of stiff grids with the advantages of flexible geogrids and can be made of various polymers. In this way the most suited polymer can be selected to fulfil the required properties in the application. Further the welding technique results in rigid connections between the straps. PET straps are used for long term applications as slope reinforcement; PP straps for applications with short term strength requirements such as road reinforcement. The results of various index tests and long-term performance tests like creep, mechanical damage and pull-out are shown. The long-term tensile strength (T_al) is calculated using the method described in FHWA-SA-96-071.