To Diagrams of Concrete Deformation under Simultaneous Action of Loading and Low Temperatures up to Minus 70°С, Depending on Structural and Technological Characteristics of Concrete

Number of journal: №6-2018
Autors:

Karpenko N.I.,
Yarmakovsky V.N.,
Karpenko S.N.,
Kadiev D.Z.

DOI: https://doi.org/10.31659/0585-430X-2018-760-6-13-19
УДК: 624.072

AbstractAbout AuthorsReferences
The initial basis of the physical ratios used to calculate the strength and deformability of reinforced concrete structures operated at low temperatures are diagrams relating the stress of axial compression and tension with relative deformations of heavy concrete, defined under normal conditions of positive temperature. On the basis of generalization and analysis of available experimental data, the correction of these deformation diagrams of heavy concrete with due regard for the effect of low negative temperature (up to -70°C) is performed. Herewith, the influence of such temperatures on increasing the prismatic strength, the initial modulus of concrete elasticity and its relative deformations at the vertices of diagrams built when testing the axial compression under the loads in a frozen state of up to -70°C is determined. It is shown that the specified increase in strength, initial modulus of elasticity and relative deformations at the vertices of the diagrams largely depends on the water-cement ratio of concrete and its initial moisture content W at the time of freezing, particularly when the latter does not exceed the limit value of Wlim, determined by the critical degree of water saturation of concrete ξcr> 90%. On the basis of processing of experimental research data it is established that the increase in durability, modulus of elasticity and ultimate deformability of the concrete tested under loading in the frozen state at temperature lower -70°C at various humidity of a cement stone (CS) and concrete in the range up to Wlim, actually stops. This pattern is confirmed by the results of special studies performed using dilatometric and ultrasonic methods of the process of phase transition of water to ice in the pores of the capillaries and pores of the gel of the CS of concrete, changes in the process of such an indicator as the” ice content” of the latter in dependence on the CS differential porosity.
N.I. KARPENKO, Doctor of Science (Engineering), Professor, Academician of RAACS,
V.N. YARMAKOVSKY, Candidate of Sciences (Engineering), Honorary Member of RAACS, Chief Researcher,
S.N. KARPENKO, Doctor of Sciences (Engineering), Counselor of RAACS, Leading Researcher,
D.Z. KADIEV, Engineer

Scientific-Research Institute of Building Physics of the Russian Academy architecture and construction sciences (21, Lokomotivniy Driveway, Moscow,127238, Russian Federation)

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For citation: Karpenko N.I., Yarmakovsky V.N., Karpenko S.N., Kadiev D.Z. To diagrams of deformation of concrete under load by the action of temperature up to -70°С depending on its structural-technological characteristics. Stroitel’nye Materialy [Construction Materials]. 2018. No. 6, pp. 13–19. https://doi.org/10.31659/0585-430X-2018-760-6-13-19 (In Russian).


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