INFLUENCE OF ELECTROLYTES ON HARDENING OF CONCRETE WITH OXYCHLORIDE MAGNESIA CEMENT AT LOW TEMPERATURES

Abstract

The specifics of performing construction and assembly works at negative ambient temperatures
requires the use of special technologies. This is especially true of concrete works requiring the
use of methods for intensifying the hardening of concrete in monolithic structures. The use of concrete
based on magnesia binder can significantly reduce the cost and duration of work, because
aqueous solutions of magnesium chlorideare used for its mixing, which are electrolyteswith a low
freezing point. The article presents the main theoretical calculations on the formation of the structure
of building composites during their hardening under negative temperatures. The factors of influence
on the processes of structure formation and hardening of magnesian concrete are revealed.
The technique of the experiment is given. The results obtained are described. An explanation is given
to the nature of the curing of magnesian concrete aged for the first 7 days of hardening in the temperature
range from –10 °C to –20 °C. A mathematical dependence of the strength of the magnesian
solution on the density of the used aqueous solution of magnesium chloride with a consumption of
binder from 50 to 25 % by weight of aggregate in the test temperature range under study is obtained.
Studies have shown that magnesian concrete shut with an aqueous solution of magnesium chloride
with a density of 1.15 ... 1.25 g/cm3 gains strength at holding temperatures from –10 °C to –20 ºС,
and negative holding temperature decreases the hardening rate by 18 ... 62 % from R28.