Concrete with polypropylene fibres

The presence of fiber in this type of concrete works like millions of bridges that uniformly distribute the internal shrinkage forces that try to separate the matrix. These same fibres intercept the propagation of microcracks, paralyze their growth, and interrupt the capillary action of moisture, thus allowing slower curing. When the fibre is mixed with a concrete matrix, the load-deformation curve increases the load capacity, which improves post-cracking, allowing it to sustain loads up to high deformation values, resulting in greater flexibility in the element.

The increase in resistance to fatigue, which is directly related to durability, impact resistance and reduction of permeability, contribute to a longer life of the concrete, benefiting the associated maintenance costs in the long term. When the concrete is subjected to stress, the micro-cracks evolve, become larger and bond with each other. As the load continues to be exerted, some of these cracks begin to become unstable and fail to push the concrete from one side to another. The fibres disrupt and stabilize micro cracks. Impact resistance (ability to absorb energy), as a way of measuring the degradation of concrete resulting from a point load, reflects the bonding characteristics of the fibres in holding together the fractured segments of originally sound concrete.

Aesthetically, fibre concrete is smoothed and finished like regular concrete. It does not require any special tools. Fibre action typically means reducing concrete slump by 20% to 30%, which creates an illusion of additional water requirement but should not be added. For slump enhancement, a superplasticizer or water reducer should be used as the addition of water would result in low strength. The aesthetic finish with fibres will depend on how the concrete was finished since in stamped concrete, the fibre will not be seen, but if the slab is smoothed by hand, some will be seen. As a general rule, the presence of fibres on concrete surfaces is acceptable. However, if not allowed, they can be removed with a blowtorch.


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