Substantiation of an express-method for determining the freeze-thaw resistance of cellular materials
An express method for determining the freeze-thaw resistance of cellular materials was offered and substantiated in this article. The proposed measurement technology of concrete frost resistance is based on the computation of the value z which is the ratio of the relative decrease of compression resistance R to the relative permanent set ε in the direction which is perpendicular to the pressure. It was found that this ratio is constant for a given composition of the concrete and does not depend on the values of R and ε. It was also proved that the values are not sensitive to the replacement of mechanical thermal cycles. These aspects will decrease the time for determining the freeze-thaw resistance of concrete and reduce the labor intensity of the tests conducted. The proposed method has been implemented on 10 samples of concrete with the following composition: Portland cement 400 (12.3 %), sand (24.7 %), granite macadam of dimensions 5…20 mm (55.6 %), water (7.4 %). Specimen cubes, according to the proposed method, were saturated with water, measured, subjected to alternate freezing and thawing and axial compression to achieve extreme loads. Then the frost resistance for each sample and the mean sample value F were calculated. The resulting value was compared with the freeze-thaw resistance, which was received for the mixture by the basic method. Thus, a new accelerated method for the determination of the freeze-thaw resistance of cellular materials was substantiated. It is highly efficient, simple, and has a low cost.