不同含水率混凝土遭受常温至-190℃间冻融循环作用的抗压强度试验研究

Experimental study on compressive strength of concrete with different water content experiencing cryogenic freeze-thaw cycles from room temperature to-190 ℃

通过不同含水率混凝土的常温至-190℃间冻融循环作用试验,探讨混凝土含水率对其超低温冻融循环作用下的受力性能影响。结果表明,不同含水率混凝土的受力性能存在明显差异。经历超低温冻融循环作用的混凝土抗压强度随其含水率的增大,上下限温度时均逐渐提高。但随冻融循环作用次数的增加,上限温度时总是呈减小态势,而下限温度时则与之完全不同、且与混凝土含水率密切相关。其超低温相对抗压强度增量随混凝土含水率的变化趋势,与未经历冻融循环作用时相同但相比均较大。依据试验与已有的研究结果,给出的经历超低温冻融循环作用的混凝土相对抗压强度增量拟合公式可用于液化天然气储罐类的超低温混凝土结构设计。

On the basis of the experiments of cryogenic freeze-thaw cydes from room temperature to -190 ℃ on the concrete with different water contents,the effect of the concrete water content on the mechanical properties of the concrete was discussed. Test results show that the mechanical properties of the concrete with different water contents were obviously different. After the the cryogenic freeze-thaw cycles, the concrete compressive strength, both at lower and upper limits of the freeze-thaw temperature,was significantly improved with the increase of the concrete water content. While the concrete compressive strength at the upper limit temperature was always decreased with the increase of the freeze-thaw cycles, totally different from that at the lower limit temperature,which was closely related to the concrete water content. The relative compressive strength increment of the concrete at cryogenic temperature after freeze-thaw cydes depends more than before on the water content. Based on the experiment results and the existing investigations results,a fitting formula of the relative compressive strength increment for the concrete experiencing the action of different cryogenic freeze-thaw cycles was given, which can be used in the design of concrete structures at the cryogenic temperature such as the LNG tanks.