Concrete is brittle and will crack with the application of increasing tensile force (strain). Once concrete cracks, it can no longer carry tensile loads.
In order to make concrete capable of carrying tension at strains greater than those at which cracking initiates, it is necessary to reinforce the matrix. At Holcim we can provide different strengths for different projects by using:
- Mesh or wire reinforcement
- Post-tensioning strands, or
- Addition of fibres
The addition of fibres to concrete will result in a composite material that has properties different to that of un-reinforced concrete. The extent of this variation depends not only on the type of fibres, but also on the fibre dosage.
In theory, the incorporation of fibres into a brittle concrete matrix can have the effect of controlling the growth and propagation of micro cracks and eventually, macro cracks. Fibres initially work to contain micro cracks that grow and join to form visible macro cracks as the tensile strain in the concrete increases.
Care is needed in using fibres as there are different types of fibres for different applications and not all fibres can be used to replace reinforcement.