DISSOLUTION BEHAVIOR OF HARMFUL ION IN MARINE SAND
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摘要: 为验证海砂淡化的有效性和海砂氯离子测试方法的准确性,分别将海底砂、淡化砂和滩砂按照1∶5固液质量比加入去离子水、饱和氢氧化钙(Ca (OH)2)溶液和水泥净浆滤液中,在3 h、1 d、7 d和28 d抽取上部澄清液测试氯离子(Cl-)、硫酸根离子(SO42-)、钾离子(K+)、镁离子(Mg2+)和钠离子(Na+)浓度,结果表明:各种离子的释出量与浸泡介质类型有关;浸泡1 d后Cl-的释出量比3 h时增加14%~25%,此后趋于稳定,未发现海砂中Cl-长期不断释出的规律;将海砂磨成粉末(<75 μm)会降低海砂Cl-释出量;SO42-在饱和Ca (OH)2溶液和水泥净浆滤液中的释出量随浸泡时间延长而降低,在水泥混凝土内可不考虑海砂中SO42-溶出的风险;K+、Mg2+和Na+在去离子水中的释出量随浸泡时间延长而趋于稳定。Abstract: To verify the effectiveness of marine sand desalination and the accuracy of testing methods for chloride ion content from marine sand, submarine sand, desalted sea sand and seabeach sand immersed were respectively in three solvents that were deionized water, saturated calcium hydroxide, and filtrate of cement paste. The mass ratio of marine and solvent was 0.2. When the soaking time arrived at 3 h, 1 d, 7 d and 28 d, the dissolved quantities(DQ) of Cl-、SO42-、K+、Mg2+ and Na+ were measured. The experimental results showed that the DQ of five kinds of ion was related to the types of soaking solvents. As the soaking time went by, the DQ of Cl- in three solvents tended to stable, and it was hard to discover the continuous dissolution, while the test value in 24 h was 14%~25% higher than that in 3 h. If marine sand was grinded into power (<75 μm), the DQ of Cl- would decline. The dissolved mass of SO42- in the filtrate of cement paste and saturated calcium hydroxide was observed to decrease with the increase of soaking time, and it was not necessary to pay close attention to the influence of SO42- of sea sand concrete. Finally, the DQ of K+、Mg2+ and Na+ in deionized water would tend to stable with the increase of soaking time.
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Key words:
- concrete /
- marine sand /
- harmful ion /
- immersion /
- dissolution
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