The general term geosynthetics encompasses the subfamilies of geotextiles, geogrids, geocells, geocomposites, and geomembranes. Various construction practices incorporate geosynthetics to take advantage of their properties and ease of installation. Geosynthetics have six primary functions: filtration, drainage, separation, reinforcement, fluid barrier, and protection. The TYPE_ of geosynthetic used on a particular project will depend on its intended primary function in the installation, and thus its critical properties
To further develop the existing specification, the Geotechnical Engineering Bureau audited recent Departmental contracts utilizing these items to determine deficiencies. The following was identified:
• Form Correction – to be placed on the Approved List, the specification requires Producers of geomembranes, prefabricated vertical drains, prefabricated composite structural drains, prefabricated composite integral abutment drains, and prefabricated composite edge drains to provide a completed Form Number SM 465 Product Evaluation Form. However, this is the incorrect form.
• AASHTO Compliant – the specification for geogrids states that the minimum permitted value for the Total Reduction Factor (RF) is 3.0. However, standard AASHTO design practice is site specific, application specific, and geogrid product specific and does not include this minimum value.
