EXPERIMENTAL STUDY ON ELASTIC MODULUS OF CONCRETE UNDERGOING FREEZE-THAW CYCLE ACTION WITH DIFFERENT ULTRALOW TEMPERATURE RANGES

Through experiments of concrete experiencing freeze-thaw cycle action with three typical ultralow temperature ranges of 10℃~-40℃, 10℃~-80℃ and 10℃~-160℃, the effects of different temperature ranges and freeze-thaw cycles on concrete elastic modulus are investigated. The test results show that with increase in the freeze-thaw action cycles the concrete elastic moduli at upper limit temperature are decreasing due to damage accumulation from freeze-thaw cycle action, and their changing trends are most obvious for the temperature range of which the lower limit temperature is lower; the concrete elastic moduli at lower limit temperature increases first due to freezing of the pore water inside concrete and then decreases with increase in the freeze-thaw action cycles, and their changing ranges are greater than those at the upper limit temperature. The concrete relative elastic modulus difference, single freeze-thaw softening index, and cumulative freeze-thaw softening index of concrete relative elastic modulus at upper and lower limit temperatures for different temperature ranges, are obviously different and their variation regularities are also more complex. The test results also reveal the relationship between the concrete relative elastic modulus and the factors of temperature range and freeze-thaw action cycles under ultralow temperature. These results can provide reference for the design and safety performance evaluation of the LNG storage tank.