Screed reinforcement is a recommendation for use in screed constructions. There are various options that can be adopted which consist of fibres or metal mesh. The general purpose is to restrain the drying stress generated from the cement in a screed system. The natural process is for the screed to try to curl and crack as well as shrinkage that is inherent in cementitious products.
The reinforcement is designed that if a crack occurs, it will hit the mesh / fibres and deflect the stress, therefore reducing the effect. A crack does not necessarily mean a failed screed and there are appropriate methods for repair, depending on the final floor finish. Generally thicker finishes, such as carpet would not require any further maintenance.
The other advantages are reduced plastic shrinkage, reduced bleeding, reduced permeability, reduced risk of delamination, increased bond, increased impact and abrasion resistance giving rise to better durability. The fibres are coated to aid the dispersal and should be placed in water prior to adding to the mix. Normally 0.9kg will be used to produce 1m3 of screed. Fibres will only replace mesh for standard applications and advice should be sort from a specialist as they do not replace the need for structural steel.
Tiles and vinyl finishes would require a repair and generally an epoxy can be successfully applied as recognised in the British Standard.The screed is required to be laid in two layers encompassing the mesh in the middle to the top third in order to be effective. The use of polypropylene fibres gives numerous advantages as this is added to the mix, the reinforcement is throughout the screed and gives a logistical advantage for placement.