Open AccessREGULARITIES OF FORMING THE STRUCTURAL STRENGTH OF VACUUM CONCRETE WHEN COMPACTING CONCRETE MIXES
Author(s) -
M. A. Storozhuk,
Т. М. Павленко,
А Р Аббасова
Publication year - 2020
Publication title -
vìsnik odesʹkoï deržavnoï akademìï budìvnictva ta arhìtekturi
Language(s) - English
Resource type - Journals
ISSN - 2415-377X
DOI - 10.31650/2415-377x-2020-81-139-148
Subject(s) - materials science , composite material , tempering , size effect on structural strength , capillary action , compressive strength , cement , liquid phase , physics , thermodynamics
Abstract. The paper presents the results of theoretical and experimental studies of structural strength and strength at the age of 28 days of vibrovacuumized and vibrated concrete. Structural strength is very important when moulding prefabricated or monolithic structures with immediate dismantling. Regularities of removal of a part of tempering water (liquid phase) from vibrovacuumized concrete mix, having capillaries of various form (round, square, formed by three or four cylinders), narrowing and expanding capillaries, and also capillaries of variable cross-section (with areas that expand and contract), are established as a result of researches. In such capillaries, the value of the capillary pressure is different and, accordingly, at different values of the external pressure, the liquid phase is removed. Also the value of breakdown pressure at which the liquid phase is removed from capillaries of variable section and with sites of small diameter is calculated. The high structural strength of vacuum concrete is theoretically substantiated. The results of experimental studies confirmed the theoretical developments and showed that the structural strength of freshly moulded vacuum concrete is 7…8 times greater than that of vibrated concrete from rigid concrete mix at the same W/C ratio, almost the same cement consumption and density. This significantly affects the strength of concrete substantiated with immediate dismantling. Due to the high structural strength, vacuum concretes do not show a decrease in strength at the age of 28 days during the moulding of structures with immediate dismantling compared to concretes, the dismantling of which was made in a day after moulding. Vibrated concretes from rigid concrete mix have such decrease in durability in the range 12…15%. These data indicate the advantages of vibrovacuumized concrete over vibrated concrete from rigid concrete mix.