Fabric formwork systems allow controlled and reliable concrete and grout construction underwater. The system overcomes marine conditions and is individually designed and purpose made. Fabric formwork systems are generally considered as lost shuttering and are usually of little interest after the concrete has set (other than the filter points of filterpoint mattress)

Fabric Formwork Systems
• Grout bags - Grouted foundations and joints to precast structures
• Concrete Mattress - Micro concrete scour protection systems
• General Fabric Formwork - General construction and repair

foundation grout bag systemBenefits
• Prevents washout
• Bottom filling avoids segregation
• Controlled compartment size
• Engineered, premade, reliable
• Avoids trapped water voids
• Lightweight, easy to fix or lay
• Adaptable to bed profiles and joint widths
• Produces good quality grout and concrete construction
• Cost effective

concrete mattress systemDesign Process
• Establish performance parameters
• Design form system
- Size and shape
- Fill and vent positions
- Fixings
- Form strength
- Fabric selection
- Joint design
- General arrangement drawings
- Fabrication drawings
• Installation Guide
- Mix design, development and testing
- Mix supply and pumping plant
- Installation method
- Filling plan

The forms, are engineer designed, to cater for the filling pressures, and to provide the required concrete section. Forms can also be prefixed and automated to precast caissons and elements or laid/ fixed by divers.

The twin stitched seams are designed and tested to produce reliable forms, which are made from a porous yet grout tight woven polyester/ polypropylene fabric which avoids entrapped water, and causes free water mix bleed while filling. This results in a significant rise in strength and abrasion resistance. For further information see Concretes and Grouts. Segregation of the mix is avoided as filler sleeve points are provided to the bottom of forms which ensures the mix is reliably placed in tremi fashion, Vents are located to the top of form compartments to control filling pressure.

Typical material specifications can be seen on the sheets :-
Single layer Fabric for Concrete and Micro Concrete (B37)
Twin Layer Fabric for Neat Cement Grouts (B88)

General arrangement drawings are developed for the concrete work allowing fabrication drawings then to be produced for approval and manufacture. Fabric formwork items are then checked before delivery.

Project specific installation guides are developed in consultation with the site team to typically cover mix design and development, mix and pumping plant, installation and filling. Where required these systems can be tested and engineers supervision and support is available on site. This often involves initial preparation works and initial concrete or grout construction works.

Diving companies most experienced with fabric formwork systems in the UK are :-
• Kaymac (www.kaymacmarine.co.uk)
• Sea Technical Services (www.seatechnical.co.uk)
• Sealane Inshore Ltd (www.sealaneinshore.co.uk)
• Seawork Marine Services Ltd (www.seaworkmarineservices.com)
• Underwater Diving Services (www.uds.co.uk)
• Valkyrie Diving and Marine Services (www.valkyriediving.com)

Contact us for experienced Diving companies overseas.

Past Projects

Second Severn Crossing (B73)

Mellenium Stadium (B76)

Grand Canal (B102)