Synthetic Fibres
Two types of synthetic fibres are available. The details of each can be found below.
Non-Structural Synthetic Fibres
Micro fine fibres are normally added at 0.6kg/m3 to provide early age crack control. Scancem's Nycon fibres are nylon. Unlike polypropylene, nylon absorbs a small amount of water giving excellent bonding. This accounts for why the fibres give excellent early age (ie plastic stage) crack control. Applications include:
- Flat slabs where site supervision to ensure early age curing is not possible
- Shotcrete lining and embankments where early age curing is extremely difficult
- Precast shapes and slip formed shapes (eg kerbs) where concrete is demoulded while green for assistance with shape control and plastic cracking is required
- Tunnel linings and concrete in structures to prevent explosive spalling in fires
Structural Synthetic Fibres
Structural synthetic fibres are large diameter (approx 1mm) polypropylene fibres that are highly deformed to increase mechanical bond. Normally dosed at 5-15kg/m3 they provide high ductility, particularly at high deflection. Applications include:
- Economic and higher performing than steel fibre in shotcrete linings in mines where high deflections are a requirement
- Where cracks might lead to rusting of steel fibres, structural synthetic can be used. At high deflections synthetics may prove more economic at low deflections they may be more expensive