摘要
"烟塔合一"排烟冷却塔混凝土内壁上的冷凝溶液含有大量的SO_4^(2-),NO_3^-,H^+,会对混凝土产生侵蚀作用.采用室内试验,对比研究了实际运行温度下普通混凝土(NC30)、高性能混凝土(HPC30,HPC50)及超高性能混凝土(UHPC)在冷凝溶液浸泡作用下的耐久性.结果表明:在冷凝溶液中浸泡95d时,NC30的质量损失率最大达到7.6%,UHPC的质量损失率仅为1.3%,而HPC30,HPC50的质量损失率分别为4.4%,4.0%.经过冷凝溶液浸泡后,NC30,HPC30和HPC50的抗压强度随浸泡时间的增加呈现先增大后减小的趋势,浸泡95d时分别减小了40.3%,31.9%和19.8%,而UHPC经过冷凝溶液浸泡后的抗压强度呈持续下降趋势,但是其损失率仅为9.4%.
The condensate solution stuck to the inner wall of natural draft cooling tower with flue gas injection contains large amount of SO 2-4,NO-3 and H+,and it could erode the inner wall concrete.Therefore,the durability of ordinary concrete(NC30),high performance concrete(HPC30 and HPC50)and ultra-high performance concrete(UHPC)in the above environment under the actual operating temperature were studied through the indoor immersion experiments.The results show that the mass loss rate of NC30 reached the maximum,which is 7.6%,after 95 days condensate solution immersion.But for UHPC the value is just 1.3%,and for HPC30 and HPC50,the value is 4.4%and 4.0%,respectively.This was caused by the reaction of H+with Ca(OH)2 during the condensate solution immersion process,which could produce soluble salt and then decompose hydration products.The compressive strength of NC30,HPC30 and HPC50 increases first and then reduces with the increase of immersion time,and their strength loss rate is 40.3%,31.9%and 19.8%,respectively,after 95 days immersion.The compressive strength of UHPC decreased with the increase of condensate solution immersion time,but its value is only 9.4%at the same time.For NC30,HPC30 and HPC50,gypsum and ettringite crystal generated during the early immersion process could fill in the inner pores and defects of the hardened cement paste and the strength of concrete was increased.But with increase of the amount of crystal products increased during the later immersion process,the expansion of crystals volume caused damage to the hardened cement paste.Combined with the action of dissolution of other hydration products caused by the reaction of H+with Ca(OH)2,the strength decreased significantly.The reaction products for UHPC was also gypsum crystal,but there was less damage to compressive strength due to its compact internal structure.The neutralization depth of NC30,HPC30,HPC50 and UHPC increased with the increase of immersion time due to the decomposition caused by the reaction of Ca(OH)2 with H+.
作者
安明喆
高扬
王月
韩松
余自若
季文玉
AN Mingzhe;GAO Yang;WANG Yue;HAN Song;YU Ziruo;JI Wenyu(School of Civil Engineering,Beijing Jiaotong University,Beijing 100044,China)
出处
《建筑材料学报》
EI
CAS
CSCD
北大核心
2018年第2期275-280,共6页
Journal of Building Materials
基金
国家自然科学基金资助项目(51578049
51278039)
关键词
排烟冷却塔
冷凝溶液
侵蚀
高性能混凝土
超高性能混凝土
耐久性
natural draft cooling tower with flue gas injection
condensate solution
erosion
high performance concrete
ultra-high performance concrete
durability
