不同超低温温度区间冻融循环作用混凝土弹性模量软化性能试验研究

通过混凝土经历10℃~-40℃、10℃~-80℃和10℃~-160℃等3种典型的超低温温度区间冻融循环作用试验，探讨不同的温度区间和冻融循环作用次数对混凝土弹性模量的影响。结果表明，随冻融循环作用次数的增加，上限温度时因冻融损伤累积使混凝土的弹性模量呈逐渐软化趋势，其中下限温度较低温度区间的变化趋势最为明显；下限温度时因混凝土内孔隙水结冰使混凝土弹性模量呈先增大后减小趋势，且较上限温度时的变化幅度更大。不同温度区间的混凝土相对弹性模量差以及上下限温度时单次冻融软化指标和累积冻融软化指标均存在明显的差异且变化规律较为复杂。该文还由试验结果拟合出混凝土相对弹性模量与超低温冻融循环作用的温度区间和次数间的关系式。所获得的这些结果可为LNG储罐类混凝土结构的设计和安全性能评估提供参考。

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.