Improvement of methods for determining power and energy characteristics of fibre-reinforced concrete crack resistance

Introduction. The actual problem of improving the methods of experimental studies of the properties of fibre-reinforced concrete obtained using various types of fibre is considered in the article. As a result of the analysis of the technical literature, some shortcomings of the existing test methods of one of the most important characteristics of fibre-reinforced concrete, crack resistance, were revealed. The aim of this study is to develop methods for determining the fibre-reinforced concrete crack resistance parameters. Materials and methods. The GOST 29167 standard is used as a basis for the development of a new method and device. Regulations of this standard pursue an aim of obtaining the most informative data about the material by plotting the dependences of test specimen deflections on the applied loads and determining with their assistance the power and energy parameters of the crack resistance. The test samples are presented by fibre-reinforced fine concrete beams made using steel wire fibre of circular cross-section and wave profile. Diagrams of the dependences of sample deflections on applied loads were plotted in the course of the tests for tension in bending. Calculations of power and energy parameters of crack resistance were conducted. Results. The device and method of testing the fibre-reinforced concrete crack resistance are developed and proved. A comparative analysis of the results of tests of steel fibre concrete samples is made. Conclusions. The proposed device and method allow researching influence of the fibre reinforcement parameters on fibre-reinforced concrete crack resistance parameters quickly and with minimal labour expenditures for preparation and tests. Increased adequacy of the obtained data promotes building up new trends in research and rapid introduction of fibre-reinforced concrete in the construction industry. As a result of the analysis of the obtained data, it is established that the proposed device and method can be recommended for research of the influence of fibrous reinforcement parameters on the obtained fibre-reinforced concrete properties and accumulation of statistical data for the development and improvement of normative and technical documents.