Fibres can be considered as an alternative to the use of an air entraining agent, in that they provide freeze thaw protection.

The mechanism by which the fibres produce resistance to freezing and thawing is:-

• Introduction of fibres reduces water absorption of the concrete increasing penetration resistance to de-icing salts.
• Reduced water absorption is a function of the fibres ability to reduce plastic shrinkage cracking, reducing the ability of water to permeate into the bleed in a concrete. Reducing another possible entry by water into the concrete in its hardened state.
• Introduction of fibres improves the toughness of the concrete, with improvements in impact and abrasion resistance. Coupled with the above, helps make the concrete less susceptible to freeze thaw damage.

Dosage and Performance
Fibrillated fibres are introduced into the concrete mix at a rate of 0.9kg/mþ. No adjustment to the mix design is required. Fibre reinforced concrete requires no special precautions and can be power floated, pumped and trowelled like other concretes.

Note:
Fibres are not a substitute for structural steel reinforcement.