自干燥及水分扩散引起的高性能混凝土内部湿度演变
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摘要
为了研究自干燥和水分扩散作用对高性能混凝土内部湿度演变的影响,将高性能混凝土分别暴露于自干燥环境和恒温恒湿环境中,并测试了混凝土的内部湿度演变规律。研究结果表明:自干燥引起的高性能混凝土内部湿度衰减主要发生在龄期28 d内,而水分扩散的影响则主要在龄期14d内。掺粉煤灰可以显著降低因自干燥和水分扩散而引起的湿度衰减,并使基体保持至少8 d的水汽饱和阶段,而掺矿粉则会加快内部湿度衰减。高性能混凝土早期内部湿度演变主要受自干燥控制,而当掺加50%粉煤灰时,水分扩散才是主导作用。此外,随着水胶比的增大或深度的减小,自干燥对内部湿度下降的影响逐渐减小,水分扩散的影响则逐渐增大。
In order to explore the influence of self-desiccation and moisture diffusion on the internal humidity evolution of high performance concrete,specimens were subjected to self-desiccation condition and constant temperature and humidity condition. Then the evolution law of humidity under above conditions was systematically investigated. The results show that the internal humidity decrement caused by self-desiccation mainly occurs within the age of 28 d while that triggered by moisture distribution mainly occurs within the age of 14 d. Besides,the adding of fly ash decreases humidity decrement significantly either induced by self-desiccation or moisture diffusion and makes the matrix stay in the moisture saturation phase for at least 8 d. However,the mixture of ground granulated blast furnace slag accelerates internal humidity decrement. Moreover,the evolution of internal humidity is dominated by self-desiccation in the early stage,and when the dosage of fly ash was 50%,moisture diffusion takes the lead. Furthermore,with increase of water to binder ratio or the decrease of depth,the percentage of self-desiccation influence on humidity decrement descends gradually accompanied by the increasing proportion of moisture diffusion influence.
In order to explore the influence of self-desiccation and moisture diffusion on the internal humidity evolution of high performance concrete,specimens were subjected to self-desiccation condition and constant temperature and humidity condition. Then the evolution law of humidity under above conditions was systematically investigated. The results show that the internal humidity decrement caused by self-desiccation mainly occurs within the age of 28 d while that triggered by moisture distribution mainly occurs within the age of 14 d. Besides,the adding of fly ash decreases humidity decrement significantly either induced by self-desiccation or moisture diffusion and makes the matrix stay in the moisture saturation phase for at least 8 d. However,the mixture of ground granulated blast furnace slag accelerates internal humidity decrement. Moreover,the evolution of internal humidity is dominated by self-desiccation in the early stage,and when the dosage of fly ash was 50%,moisture diffusion takes the lead. Furthermore,with increase of water to binder ratio or the decrease of depth,the percentage of self-desiccation influence on humidity decrement descends gradually accompanied by the increasing proportion of moisture diffusion influence.
引文
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18 Yao Y M,Shi H S,Shi T. Cement,2006,9(4),1(in Chinese).姚玉梅,施惠生,施韬.水泥,2006,9(4),1.
2 Parrott L J. Magazine of Concrete Research,1991,43(154),45.
3 Terrill J M,Richardson M,Sekby A R. Magazine of Concrete Research,1986,38(137),220.
4 Kima Jin-Keun,Lee Chil-Sung. Cement and Concrete Research,1999,29,1921.
5 Akita H,Fujiwara T,Ozaka Y. Magazine of Concrete Research,1997,49(179),129.
6 Neveille A,Pierre-Claude Aitcin. Materials and Structures,1988,206(31),111.
7 Persson B. Materials and Structures,1997,199(30),293.
8 Ahmed Loukili,Abdelhafid Khelidj,Pierre Richard. Cement and Concrete Research,1999,29,577.
9 Uchikawa H,Hanehara S,Hirao H. ACI Special Publications,1997,2,949.
10 Jiang Z W,Sun Z P,Wang P M. Journal of the Chinese Ceramic Society,2003,31(8),770(in Chinese).蒋正武,孙振平,王培铭.硅酸盐学报,2003,31(8),770.
11 Jiang Z W,Wang P M. Journal of Wuhan University of Technology,2003,25(7),18(in Chinese).蒋正武,王培铭.武汉理工大学学报,2003,25(7),18.
12 Benz D P. Cement and Concrete Research,2008,38,196.
13 Jiang Z W,Sun Z P,Wang P M. Fly Ash Comprehensive Utilization,2003(2),16(in Chinese).蒋正武,孙正平,王培铭.粉煤灰综合利用,2003(2),16.
14 Jiang Zhengwu,Sun Zhenping,Wang Peiming. Cement and Concrete Research,2006,36,320.
15 Huang Y,Qi K,Zhang J. Journal of Tsinghua University(Science and Technology),2007,47(3),309(in Chinese).黄瑜,祁锟,张君.清华大学学报(自然科学版),2007,47(3),309.
16 Zhang J,Chen H Y,Hou D W. Journal of Building Materials,2011,14(3),227(in Chinese).张君,陈浩宇,侯东伟.建筑材料学报,2011,14(3),227.
17 Yuan R Z. Cementious materials science,Wuhan University of Technology Press,China,1996(in Chinese).袁润章.胶凝材料学,武汉理工大学出版社,1996.
18 Yao Y M,Shi H S,Shi T. Cement,2006,9(4),1(in Chinese).姚玉梅,施惠生,施韬.水泥,2006,9(4),1.