Mirafi® SRW-Series Woven Geotextiles for segmental Retaining Wall Reinforcement
Product Description
Mirafi® SRW-Series woven geotextiles are manufactured with a unique weaving techniques which utilize high tenacity polyester and/or polypropylene yarns. This weaving structure produces outstanding strengths and water rate properties. SRW-Series Woven Geotextiles yield Long Term Design Strengths up to 18.4 kN/m (1260 lbs/ft), cross-machine direction, per GRI-GT7.
Features and Benefits
Applications
Retaining walls are common structural features facilitating highway alignment, enhancing building sites, and improving aesthetics within residential communities around the world. The success of the segmental retaining wall depends on proven design principles, excellent material performance, and sound construction principals. The proven concept of tensile reinforcement forms the foundation for geosynthetic reinforced retaining walls.
Because of their flexibility and versatility, woven geotextiles are used in a variety of applications. The SRW-Series Woven Geotextiles have been developed specifically for use as Segmental Retaining Wall reinforcement. SRW-Series Geotextiles have been designed around the three main SRW parameters: strength (LTDS and connection) per unit cost ratio; water flow rate to ensure adequate release of hydrostatic pressure; ease of installation. For Segmental Retaining Walls, SRW-Series products are the logical choice.
Installation Guidelines*
Careful planning and preparation for each installation step will speed construction and eliminate costly mistakes. Geosynthetics are installed in layers at specific elevations. These layers are spaced throughout the reinforced structure depending on the design. Placement of the proper reinforcement product at the correct elevation with the specified embedment length is critical to the function of the structure. Prior to the placement of the geosynthetic reinforcement, the excavation shall be cleared of all construction debris, sharp objects, large stones, and excess fill material.
Orientation of the geosynthetic is of extreme importance. Prior to installation of the geosynthetic, determine if the machine direction (warp) or cross-machine (fill) direction is to be used as the principal reinforcement direction. (NOTE: With SRW300, the cross-machine direction is most often used as the principal reinforcement direction.)
If the machine direction is the principal reinforcement direction, roll out the material perpendicular to the wall face and cut the geosynthetic to the required embedment length as depicted on the design drawings. (NOTE: A razor blade, scissors, or sharp knife is suitable for cutting the geosynthetic.) If the cross-machine (fill) direction is the principal reinforcement direction, roll out the material parallel to the wall face. Orientation is project specific, so be sure to verify with the project engineer or your TC Mirafi® Technical Representative.
After being rolled out, the geosynthetic should be tensioned by hand until it is taut, free of wrinkles, and lying flat, The geosynthetic can be held in place with staples, pins, stakes, sand bags, or fill material. No overlaps or seams are allowed across the principal strength direction of the geosynthetic. Adjacent sections shall be butted in a manner to assure 100% coverage after placement.
Placement of fill should be done by standard methods. However, extreme care should be taken during placement of fill to prevent wrinkle development and/or slippage of the geosynthetic. Rubber-tired equipment can be allowed to pass over the geosynthetic but at low speeds and without sudden breaking or sharp turns. Tracked equipment shall not be allowed on the bare geosynthetic. However, six inches of fill on top of the geosynthetic is sufficient to prevent tracked equipment from damaging the materials. Each lift of fill shall be compacted with subsequent layers of geosynthetic material by repeating the above steps.
*These guidelines serve as a general basis for installation. Detailed instructions are available from your TC Mirafi® representative.
Importance of Geotextile Permeability
All geosynthetics are not created equal. Slit tape geotextiles are commonly used in soil stabilization/separation applications in which tensile strength is the primary concern. While they produce adequate tensile strengths, slit tape geotextiles exhibit poor water passing characteristics thus making them less desirable for retaining wall applications.