Fibrecrete

The classic concrete structure is reinforced by a steel bar reinforcement. In some cases, it is advantageous to partially or completely replace the steel bar reinforcement with the fibre reinforcement. The fibres can be steel, in which case it is called steel-fibre reinforced concrete, or they can be non-metallic, in which case it is called fibrecrete.

Steel-fibre reinforced concrete has long been studied in Metrostav and was used, for example, on the tubbings of the Ejpovice tunnel. The disadvantage of wires is their susceptibility to corrosion, in some cases also their magnetic properties, or mechanical action if they protrude from the surface. These disadvantages are eliminated when non-metallic fibres are used. The disadvantage of many non-metallic fibres is their small modulus of elasticity, i.e. high deformability. This disadvantage can be partially eliminated by a high number of fibres. The bulk density of non-metallic fibres is also significantly smaller.

The subject of the research in terms of the CESTI research project supported by the Czech Technology Agency was the behaviour of concrete reinforced with non-metallic so-called macrofibres. Macrofibres with a length of 39 mm and a diameter of 0.78 mm were tested. The basic test is the bend of a standard beam of dimensions 150 x 150 x 700 mm. In the 4-point bend test to a span of 600 mm, the relationship between load and deflection of the beam is determined. Different dosages were tested. The last stage of the research was related to verifying the function of macrofibres in a simple structure. A part of the research was also verification of the technology of production of fibrecrete elements under real-world conditions of mass production.