Statistical patterns of changes in internal resistance parameters of cement composites during freezing and thawing

Abstract

The article presents the results of an experimental part of the probabilistic and statistical approach to the design accounting of consequences caused by non-stationary stochastic changes in the temperature and humidity of external environment. Cryogenic effects of the environment are modelled by cyclic freezing tests according to the third method of GOST 1006-2012. Two series of cubic and prismatic (100 × 100 × 400 mm) samples were tested, including standard concrete (SC) and fibrous concrete (FC, µ = 1.5%) reinforced by polypropilen fibres with df = 0.8 mm diameter and lf = 40 mm length. Following the specified number of cycles, the samples were subject to axial compression under the constant deformation rate of 5·10-3 1/s. The kinetics of cyclic freezing and thawing is analysed. In addition, the cross-correlation between the statistics of the strength and deformability distribution in the standard and fibrous concretes was assessed using complete σb – εb diagrams and discrete models corresponding to different stages of the deformation response. It is proposed to differentiate the criteria conditions for assessing the consequences of climatic structural degradation taking into account the usability specification of structures.