Methods for determining the limits of the microcrack formation

Microcracking is one of the fundamental characteristics of concrete behavior. Existing dependencies to determine the relative values of the limits of microcrack formation are currently losing their relevance, since they were derived for conventional concrete, and in construction, concretes of various types improved strength and/or deformability are increasingly used. In this paper new empirical relationships are proposed for determining the relative values of the mi-crocrack formation limits. The proposed fomulas are universal and can be applied to determine the limits of microcracks formation for concretes of various types (studied normal concrete, steel fiber concrete, claydite, concrete with the use of a cupola slag as a fine aggregate). The type of concrete is taken into account by the empirical coefficient kcrc. The coefficient value depends on the ratio of the relative values of the lower ηcrc0 and the upper ηcrcv microcrack formation limits (ηcrc0 / ηcrcv = const). The research was carried out within the frame-work of the state program of scientific research in the field of “Physical Materials Science, New Materials and Technologies” at the Belarusian-Russian University. Comparison of the calculation results and experimental data (own and other researchers) showed good convergence: the deviation of the calculated values from the experimental data is 4–7%. Evaluation of the va-lidity and reliability of the proposed mathematical model was performed according to the Eurocode. In conclu-sion, the prospects for further research are also given.