Filter Fabric Sheet Drains provide a cost effective option to the conventional use of aggregate for vertical or horizontal drainage on retaining walls, foundation walls, podium decks and landscape drainage. GA Cuspated Sheet Drains reduce the hydrostatic pressure behind walls and the potential for structural failure because they intercept high volumes of water and allow it to quickly drain from the site.
Filter fabric sheet drains are a composite geosynthetic made from a high quality, abrasion resistant, non-woven geotextile filter fabric bonded to an impermeable HDPE sheet cuspated under heat and pressure to form a high flow dimpled drainage core. The filter fabric prevents soil or sand particles from blocking the dimpled core and creates an air gap so that the wall can breathe and moisture condensates outward onto the membrane. The moisture then falls to a footing drain where it is removed. The dimpled core transports large volumes of water and its high compressive strength resists loads from infill and formwork. Whilst it can be difficult to accurately calculate seepage through non homogeneous soils, GA Sheet Drains ensure that the permittivity into the core and the in plane flow rate remain constant.
Waterproofing Membrane Protection
GA Geocomposite Sheet Drains provide effective drainage and waterproofing membrane protection for both horizontal and vertical tanking applications. During backfilling or landscaping the stiff plastic sheet protects waterproofing membranes from sharp stones, traffic from on-site workers and tools from construction trades. GA Cuspated Sheet Drains also act as a thermal insulation barrier adjacent to the waterproofing membrane. They can be applied to cement and highly textured surfaces.
Road and Rail Tunnel Drainage
Because of the variation in permeability and grain size, the velocity of seeping water through porous media varies greatly (Darcy’s Law). GA Dimpled Sheet Drain is designed to collect and drain large volumes of unwanted surface and groundwater from road and rail tunnels. It’s high strength withstands ground pressures and the compaction forces of wet concrete. When connected to the tunnel’s drainage discharge system GA Sheet Drain maintains a high water flow and eliminates hydrostatic build-up against the structure.
The GA Dimpled Sheet Drain also protects the waterproofing membrane from damage. The dimpled drainage core creates an air void to isolate the structure from the effects of the surrounding ground.
Podium decks and rooftop gardens
Podium decks are an easy way to create extra living space in places that offer private or public access. They also have environmental benefits, such as reducing the heat island effect of cities, and the load on stormwater systems during heavy rain.
Natural and artificial grass, concrete and natural stone pavements are usually installed on roof tops and balconies. To maintain the integrity of the surrounding structure, a light weight drainage system, specifically designed for this purpose should be installed.
Geosynthetics Australia’s 18mm high double cuspated sheet filter drain captures and transports large volumes of water and resists high mechanical loads from earth and formwork. Its multi-faceted role includes: stopping water pooling on the surface; preventing a build-up of hydrostatic pressure on the underlying waterproofing membrane; creating an air gap for reliable ventilation; and managing sub-surface water around building foundations.
Applications for Filter Fabric Sheet Drains
- Retaining wall drains
- Road and rail tunnels
- Roof garden drains
- Basement walls and foundations
- Reducing hydrostatic pressure behind vertical structures
- Waterproofing membrane protection
- Landscape drainage
- Bridge abutments
GA sheet drains are available in rolls 1.1m x 20m. For larger applications sheet drains are available in widths up to 2.2 metres, with or without a filter fabric. Dimple heights ranging from 10mm to 30mm are available for various applications.
Filter fabric sheet drains are installed either vertically or horizontally with the geotextile facing towards the soil and the geomembrane against the wall. During backfilling with free draining fill, wall drains are held in place by either taping, nailing, gluing or hanging over the wall. It is important not to disturb or damage the filter fabric during this process. For wider areas, the dimples along the edges of the sheets are easily pressed together or butted edge to edge and secured with reinforced tape.
|Core Properties||Units||10 Single||20 Single||18 Double||Geotextile Properties|
|Compression (ASTM-1621)||kPa||500||200||250||Flow||>200 l/m2/s|
|Flow||l/min/m width||223||480||450||EOS||<0.12 mm|
|Roll length||m||30||30||30||Grab||>500 N|