The analysis of experimental data showed that the main reason for obtaining various results when testing two approximately the same batch of bricks according to two different modes is that air loss with bricks when testing under the first regime was much less than when testing the second regime. But the larger the speed of air loss, ceteris paribus, the less cycles are required to destroy brick.
Since both tested batch of bricks were approximately the same, the different speed of air loss can be explained by the difference in the duration of freezing and thawing bricks with tested modes. Thus, the determination of the frost resistance of brick should include a well -defined duration of the processes of freezing and thawing, since only in this case it is possible to count on the receipt of unambiguous results during the testing of brick with various laboratories. It would be the most convenient to set the duration of freezing and thawing at 6 o’clock, which with three -shift work of laboratories will allow two test cycles per day. With single -shift work of the laboratory, the duration of freezing remains the same, and the duration of thawing increases to 18 hours. Criteria for evaluating test results. The nature of the destruction of brick when testing for frost resistance is different. Destruction can manifest itself in an increase in the existing cracks or in the form of newly formed cracks, sprouts or in splitting brick into parts, in the form of discharge of plates and, finally, in the form of peeling of surfaces (usually spoon and pumpkin).The current GOST 7025-54 provides not a very clear criterion for assessing the test results. Brick is considered frost -resistant if, after 15 cycles of testing, it will not show any signs of destruction.