METHOD OF DETERMINING CRITICAL STRESS INTENSITY FACTOR OF CONCRETE AFTER IMPACT OF HIGH TEMPERATURES THEREON Russian patent published in 2017 - IPC G01N3/24 

FIELD: construction.

SUBSTANCE: sample-prism of concrete at the age of 28 days or more, stored under normal conditions, is subjected to heating in an electric furnace with the temperature rise rate of 2°C/min up to the temperature of 100 to 700°C, then is held for 4 hours at the maximum temperature, then after the natural cooling in the furnace, a stress concentration area is formed in the sample by means of applying two symmetrical incisions on one face of the concrete sample, after which the sample is loaded to destruction, and the destructive load is measured. The critical stress intensity factor is determined by the formula where P is the destructive load, MH; Y (l, b) - the correction factor; t - the sample width, m; H - the distance from the incision to the sample face, m; l - the incision depth, l=b/4, here b is the sample height, m.

EFFECT: increasing the accuracy and reliability of determining the critical stress intensity factor by forming areas of stress concentrations in the form of incisions.

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