A Laboratory Protocol for Simulating Installation Damage in PVC-Coated PET Woven Geogrids Based on a Targeted Reduction Factor

During the construction of geogrid-reinforced earth structures, geogrids are often subjected to compaction-induced damage, which may reduce their tensile strength. This potential loss is typically addressed by applying a reduction factor to the tensile strength for installation damage (RFID). The RFID values can be determined from the existing standard protocols by testing a specific geogrid. This approach works well for design purposes, but if the intention is to produce damaged geogrid specimens for further investigation, where the damage is associated with specific RFID values, the existing standard protocols fall short. The focus of this study is to close this gap by presenting an approach on how to create uniform damage distribution on the geogrid surface that corresponds to a specific RFID value. The procedure was developed using a polyvinyl chloride (PVC) coated polyester (PET) woven geogrid because of the wide usage of this type of geogrid as reinforcement. Based on the literature, two target RFID values were selected for this study. For consistency with existing standard protocols, the geogrid was compacted between aggregate layers. Damage was created by changing the compaction energy and the thickness of the aggregate layer above the geogrid. The uniformity of damage was confirmed through image analysis and the magnitude of strength loss using single-rib tensile tests. The tensile strength test results were also used to confirm target RFID values.