INFLUENCE OF PRE-CURING PERIOD AT SUB-ZERO TEMPERATURE (-20℃) ON THE COMPRESSIVE STRENGTH OF CONCRETE

  • NARANTOGTOKH Bayarjavkhlan
    TOHOKU UNIVERSITY, Graduate School of Engineering(6-6, Aramaki Aza Aoba, Aoba-ku, Sendai-shi, Miyagi 980-8579, Japan)
  • NISHIWAKI Tomoya
    TOHOKU UNIVERSITY, Graduate School of Engineering(6-6, Aramaki Aza Aoba, Aoba-ku, Sendai-shi, Miyagi 980-8579, Japan)
  • PUSHPALAL Dinil
    TOHOKU UNIVERSITY, Graduate School of International Cultural Studies(41, Kawauchi, Aoba-ku, Sendai-shi, Miyagi 980-8576, Japan)
  • TANIGUCHI Madoka
    HOKKAIDO RESEARCH ORGANIZATION(Kita19-jo Nishi11-chome, Kita-ku, Sapporo-shi, Hokkaido 060-0819, Japan)

抄録

<p>Average temperatures over most of Mongolia are below freezing from November through March. The lowest temperatures in January are as low as -36℃ to -40℃. However, in the extremely cold climate of Mongolia, it is often executed the concrete works even outside temperature is below -20℃. Therefore, in this experimental work, we investigated the required time span of pre-curing in order to achieve the potential strength at 28 days before being exposed to extremely low temperature(-20℃), simulating Mongolian weather conditions. Moreover, internal temperature changes and microstructure analyses have been executed. We have found that concrete freezing temperature decreases remarkably from 0℃ to -15.6℃ with increasing pre-curing time, however, depending on the water-cement (W/C) ratio. Our experiments have shown that there was no freezable water after 14 days when the W/C ratio is below 0.39. Our research concluded that concrete should at least be cured at 20℃ for 14 days before being exposed to sub-zero temperatures, in order to reach in fair to middling potential strength at 28 days.</p>

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