不同强度等级混凝土超低温冻融循环作用下的变形性能试验研究  

Experimental study on deformation performance of different strength grade concretes experiencing ultralow temperature freeze-thaw cycle action

作　　者：时旭东[1] 田佳伦 汪文强[1] Shi Xudong;Tian Jialun;Wang Wenqiang(Department of Civil Engineering, Tsinghua University, Beijing 100084, China)

机构地区：[1]清华大学土木工程系,北京100084

出　　处：《低温工程》2021年第1期35-42,74,共9页Cryogenics

基　　金：国家自然科学基金项目(No.51878375、No.51478242)。

摘　　要：通过试验探讨设计强度等级分别为C40、C50及C60混凝土经历超低温冻融循环作用的受压峰值应变、受压应力应变曲线和热变形等变形性能。其作用的超低温温度区间为15—-120℃和15—-190℃,冻融次数分别取0次、16次和30次。结果表明,不同强度等级混凝土的相对受压峰值应变上限温度时随冻融循环作用次数增加变化不大,下限温度时则随冻融循环作用次数增加基本上呈现不断地减小趋势。而相对受压应力应变曲线上下限温度时相近、均呈现出先内凹后外凸的性态,且随强度等级的提高这种性态更为明显;经历超低温冻融循环作用混凝土的热变形较为复杂,但其热膨胀系数随冻融循环作用次数的增加呈现出先逐渐地增大后近于恒定的变化趋势。所获得的试验结果及其相应的拟合公式可为超低温混凝土结构的设计计算分析提供依据。Through experiment of concrete with designed strength grades of C40,C50 and C60 experiencing ultralow temperature freeze-thaw cycle action,the deformation properties including the compressive peak strain,compressive stress-strain curve and thermal deformation were investigated.The imposed ultralow temperature ranges were 15 to-120℃and 15 to-190℃,and the corresponding freeze-thaw cycle action times(N)were 0,16 and 30 respectively.The test results show that with the increase in N the relative compressive peak strain of concrete with different strength grades does not change much at upper limit temperature and basically shows a continuous decrease trend at lower limit temperature.However,the behavior of the relative compressive stress-strain curves at lower limit temperature is similar to that at upper limit temperature,showing the curve behavior of first concave and then convex,and this behavior becomes more obvious with the increase in concrete strength grade;the thermal deformation of concrete undergoing ultralow temperature freeze-thaw cycle action is more complicated,but its thermal expansion coefficient with the increase in N shows a trend of gradually increasing first and then nearly constant.The test results obtained in this paper and the corresponding fitting formulas can provide a basis for the calculation and analysis of designing ultralow temperature concrete structures.

关 键 词：混凝土 强度等级 超低温 冻融循环作用 变形性能 

分 类 号：TB69[一般工业技术—制冷工程] TU528[建筑科学—建筑技术科学]