经历常温降温及再回温的混凝土受力性能试验研究
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摘要
通过对C50混凝土经历常温分别降至-40,-120,-190℃及再回温试验,探讨其受力及热变形性能随温度及其作用方式的变化规律。结果表明:经历常温降温混凝土的受压强度、弹性模量和峰值应变均大于常温,且随作用的温度降低而增大,但后期趋势减缓;而经历常温降温再回温混凝土的受压强度、弹性模量和峰值应变则均小于低温时,且随两者差值的增大,基本上呈线性下降趋势。其中弹性模量的下降幅度很小。经历超低温作用混凝土的降温阶段的热变形随温度降低,开始增大然后呈变缓趋势,其回温阶段则与之不同,且存在残余热变形;相应的热膨胀系数在超低温温度较低时均表现出明显的减小。
Through the experiment of C50 concrete experiencing cooling from room temperature to -40 ℃,-120 ℃and-190 ℃ and then back to room temperature,the changing regularities of mechanical properties and thermal deformations of concrete with change in ultra-low temperature and its action mode were discussed. From the test results,it was shown that the compressive strength,elastic modulus and peak strain of concrete during cooling from room temperature to ultra-low temperature were all greater than that only at room temperature,and increased with declining in ultra-low temperature,but the increasing rates became smaller in the later period. However,the compressive strength,elastic modulus and peak strain of concrete during cooling from room temperature to ultra-low temperature and then back to room temperature were all lower than that at low temperature,and they had a linear decreasing trend with declining in temperature,but the decline in its elastic modulus was relatively small. The thermal deformations of concrete under ultra-low temperature increased first and then decreased with declining in temperature,but it had an obvious difference when back to room temperature and there existed residual thermal deformations. The thermal expansion coefficient decreased obviously at ultra-low temperature.
Through the experiment of C50 concrete experiencing cooling from room temperature to -40 ℃,-120 ℃and-190 ℃ and then back to room temperature,the changing regularities of mechanical properties and thermal deformations of concrete with change in ultra-low temperature and its action mode were discussed. From the test results,it was shown that the compressive strength,elastic modulus and peak strain of concrete during cooling from room temperature to ultra-low temperature were all greater than that only at room temperature,and increased with declining in ultra-low temperature,but the increasing rates became smaller in the later period. However,the compressive strength,elastic modulus and peak strain of concrete during cooling from room temperature to ultra-low temperature and then back to room temperature were all lower than that at low temperature,and they had a linear decreasing trend with declining in temperature,but the decline in its elastic modulus was relatively small. The thermal deformations of concrete under ultra-low temperature increased first and then decreased with declining in temperature,but it had an obvious difference when back to room temperature and there existed residual thermal deformations. The thermal expansion coefficient decreased obviously at ultra-low temperature.
引文
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[6]戢文占,张涛,王宝华,等.混凝土在超低温环境下的力学特性研究[J].混凝土,2014(6):45-47.
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[8]ROSTASY F S,WIEDEMANN G.Strength and Deformability of Concrete After Low Temperature Cyc1es[C]∥Proceedings,Second International Conference on Cryogenic Concrete.Newcastle:1983.
[2]李响,谢剑,吴洪海.超低温环境下混凝土本构关系试验研究[C]∥第22届全国结构工程学术会议论文集.乌鲁木齐:2014:195-200.
[3]LEE G C,SHIH T S,CHANG K C.Mechanical Properties of Concrete at Low Temperature[J].Journal of Cold Regions Engineering,1988,2(1):13-24.
[4]段桂珍,方从启.混凝土冻融破坏研究进展与新思考[J].混凝土,2013(5):16-20.
[5]时旭东,居易,郑建华,等.混凝土低温受压强度试验研究[J].建筑结构,2014(5):29-33.
[6]戢文占,张涛,王宝华,等.混凝土在超低温环境下的力学特性研究[J].混凝土,2014(6):45-47.
[7]山根昭,赵克志.超低温混凝土[J].低温建筑技术,1980(1):60-63.
[8]ROSTASY F S,WIEDEMANN G.Strength and Deformability of Concrete After Low Temperature Cyc1es[C]∥Proceedings,Second International Conference on Cryogenic Concrete.Newcastle:1983.