Fibres in mortar: polypropylene and cellulose fibres do different jobs

Same word, two materials

In construction chemicals, "fibre" can mean two different things. Polypropylene (PP) fibre acts as micro-reinforcement inside the mortar. Cellulose fibre is an additive that holds water and adjusts consistency. One can't replace the other, but they sit happily in the same formulation.

Polypropylene fibre

A synthetic fibre that resists water and alkalis. It disperses through the mortar and forms a three-dimensional network. That network prevents plastic shrinkage cracks, raises impact resistance and lowers permeability.

It is used in concrete, renders, screeds, gypsum, site concrete and precast elements. MSA's 6 mm polypropylene fibre is supplied as micro-reinforcement for these applications.

Cellulose fibre

A plant-based cellulose fibre. Because it holds water, the mortar stays workable longer before it dries out. It also improves adhesion and reduces tile slip in ceramic adhesives.

Using both

An ETICS base coat is a good example. PP fibre controls cracking, while cellulose fibre helps the mortar spread easily and bond well. The two dosages are set independently. If you'd like to work out the ratios for your own formulation, get in touch with our team.