INFLUENCE OF POLYPROPYLENE FIBRES ON SELECTED PROPERTIES OF SELF-COMPACTING CONCRETE

The self-compacting concrete proved to be the most revolutionary achievement of the engineering in the last 25 years. Its numerous advantages encourage an expanding research of this composite. One of the aspects of the research is its properties modification by an addition of fibres as a dispersed reinforcement. In the technology of the self-compacting concrete this problem is still little known. The technology of the self-compacting concrete is a difficult subject due to a large "sensitivity" of the composite on any qualitative and quantitative variation of mix components. An increase of a fibre content in a volume of the self-compacting concrete enhances properties of a hardened composite and on the other hand deteriorates its properties during the forming stage. The paper presents results of experiments on an influence of polypropylene fibres on selected properties of the self-compacting concrete. It is concluded, that a small addition of the fibres does not evoke any change in rheological properties of the concrete mix. Only a small disturbation of self-deaeration was observed leading to a small increase of concrete porosity and water absorption. The fibres decreased the concrete shrinkage, increased water-tightness and did not cause any decrease of compressive strength.