Stress–Strain Properties of Concrete at Early Freezing

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AbstractStudies show that the influence of negative temperatures is manifested both in the strengthening of the concrete structure and in its destruction. The destruction of concrete is associated primarily with the formation of ice in the pores. The resulting forces act destructively on the concrete structure if it does not have a certain strength. Strengthening of concrete occurs due to microcracks, a decrease in the concentration of tensile stresses at the mouths of cracks. Thus, it has been established that concrete, due to the presence of a liquid phase, continues to harden even at negative temperatures, but the quantitative side of this phenomenon has not been studied enough. The article provides an analysis of temperature deformations and changes in the structure of concrete during freezing, which depend on the resulting action of two groups of mutually opposite forces—freezing forces at the phase boundaries and internal pressure forces of the formed ice that violate the internal connection of concrete components. In this article, the products formed during the hydration of silicate minerals at low positive and negative temperatures are also considered, which differ markedly in their composition from those arising under normal conditions.KeywordsStructure of concreteDeformation of concreteIntensity of loadingCement hydrationThermodynamic properties