Theoretical Aspects, Experimental Investigations and Efficiency in Concrete Reinforcement by Organic Fibres

Abstract

Fibre concrete is a composite material reinforced by fibres. Construction of facilities while using concrete reinforced by organic fibres has rather long history. An analytical review of national and international investigations have shown that application of fibre concrete for bridge and tunnel structures significantly improves their physical and mechanical indices and, firstly, their service life. 3D strengthening of fibre concrete fundamentally changes properties of cement stone while ensuring high crack resistance of structures, increasing their resistance to impact and dynamic loads. Changes in volume ratio of various fibres in concrete make it possible to regulate material properties. It permits to increase its tensile strength, corrosion resistance, weather resistance and resistance to periodical moistening-drying and freezing-defrosting processes, and other indices are improved as well. The paper presents the developed technologies and fibre concrete compositions and contains description of manufactured and tested experimental specimens of non-pressure pipes reinforced by polypropylene fibres. The executed investigations have shown that the polypropylene fibres reduce probability of crack initiation and prevent their enlargement and when they are operated they depress growth of cracks and concentration of stresses in the field of macrodefects. Due to introduction of the fibre re-distribution of stresses caused by the process of structure formation has occurred from places of their concentration for the whole concrete volume. The fibre increases concrete resistance to compression and also improves service life of concrete at low temperatures and aggressive reagent action. The polypropylene fibres is expediently to apply for disperse reinforcement of structures working in bending, for example, being used for tunnel liner, bridge structures, concrete non-pressure pipes etc.