Creep behavior The creep behavior was determined by an independent expert laboratory using the ASTM D6992 standard. The isochronous curves were obtained according to this test, which was performed during several months at several strains on a creep bench. The reduction factor for creep is obtained from the isochronous curves, getting the remaining fraction of the initial ultimate tensile strength (load UTS) at the allowed elongation (determined by the geotechnical design), as written in the following formula (Equation 5): (5) Installation damage The installation damage reduction factor has been determined by doing in situ tests (as described in NF G38-064 and ISO/TR 20432 standards). Strips of the product have been backfilled with several soil types, from fine soils to gravel 0-12 inches (0-300 mm) (Figure 5). After exhuming the product, a visual inspection was carried out. The woven geotextile on one side of the GEOTER F reinforcement geosynthetic protects the high-tenacity yarns. Therefore, the product presents less degradation than most uncoated geosynthetics on the market. Tensile strength tests have been carried out on the exhumed product by an independent laboratory to determine the installation damage reduction factor function of the tested soils (Table 1). Durability The high-tenacity yarns of the selected reinforcement geosynthetic are made of PVA. Oxidation has been identified to be FIGURE 5 In situ tests with several types of soil over the geosynthetic the significant degradation mechanism of PVA. Tests on PVA yarns in wet and dry cycles for the use in reinforced earth structures (Nait-Ali and Freitag 2009) results in a reduction factor for durability of 1.2. Applying the reduction factor to the allowable tensile strength determined by the geotechnical design led to the selection of the reinforcement geosynthetic with PVA high-tenacity yarns and UTS of 2,570 pounds-force per inch (450 kN/m): GEOTER F PVA 450. Fine material RFID 1.05 Sand < 2 mm Gravel 0/100 mm Gravel 0/300 mm 1.19 1.15 TABLE 1 Reduction factor for installation damage (RFID) for several types of soil in contact with the reinforcement geosynthetic www.GeosyntheticsMagazine.com 27 1.26http://www.GeosyntheticsMagazine.com