INVESTIGATION OF RESISTANCE OF CEMENT PASTE TO SULFATE ATTACK
INVESTIGATION OF RESISTANCE OF CEMENT PASTE TO SULFATE ATTACK
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发表时间：
1966
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通讯作者：
J. Nielsen
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作者：
J. Nielsen
试验研究了水泥浆密度对反应过程的影响，部分通过对测试样本的薄片进行显微镜检查，部分通过测定所消耗的硫酸盐。通过将测试样品储存在硫酸钠、硫酸镁、硫酸亚铁和硫酸铁中，还研究了金属离子对反应过程的影响。测试样本由边缘长度为 25 毫米的水泥浆立方体组成。使用三种不同的水灰比，在水中固化 7 天后，将立方体储存在四种盐中每种盐的 0.07 摩尔溶液中。每个月都会更换溶液以保持浓度大致恒定。样品储存约 2 个月后，开始系统测定硫酸盐消耗量。该系列/硫酸钠、硫酸镁和硫酸亚铁/中的硫酸盐总消耗量大幅增加，但解决方案之间的时间差异变得明显。薄片的显微镜检查显示石膏是主要的硫酸盐反应产物。钙矾石主要存在于储存在硫酸钠中的样本中。得出以下结论' /1/ 溶液的侵蚀性从硫酸钠、硫酸镁到硫酸亚铁不断增加， /2/ 水泥浆的抵抗力可以通过增加其密度来提高，以及 /3/ 薄片检查表明钙矾石的形成量很少足以引起裂纹。参考文献《硬化波特兰水泥浆中不可蒸发水的测定》，L. E. COPELAND，J. C. HAYES，ASTM BULL，V. 194，PP 70-74，1953。
TESTS INVESTIGATED THE EFFECT OF CEMENT PASTE DENSITY ON REACTION COURSE PARTLY BY MICROSCOPIC EXAMINATION OF THIN SECTIONS FROM THE TEST SPECIMENS AND PARTLY BY DETERMINATION OF SULFATE CONSUMED. THE EFFECT OF THE METAL IONS ON THE COURSE OF THE REACTION WAS ALSO INVESTIGATED BY STORING TEST SPECIMENS IN SODIUM SULFATE, MAGNESIUM SULFATE, FERROUS SULFATE, AND FERRIC SULFATE. THE TEST SPECIMENS CONSISTED OF CEMENT PASTE CUBES WITH AN EDGE LENGTH OF 25 MM. THREE DIFFERENT WATER CEMENT RATIOS WERE USED AND AFTER 7 DAYS CURING IN WATER, THE CUBES WERE STORED IN 0.07 MOLAR SOLUTIONS OF EACH OF THE FOUR SALTS. THE SOLUTIONS WERE CHANGED EACH MONTH TO KEEP THE CONCENTRATIONS APPROXIMATELY CONSTANT. AFTER THE SPECIMENS WERE STORED FOR ABOUT 2 MONTHS, SYSTEMATIC DETERMINATION OF THE SULFATE CONSUMPTION COMMENCED. THERE WAS A STRONG INCREASE IN THE TOTAL SULFATE CONSUMPTION IN THE SERIES /SODIUM SULFATE, MAGNESIUM SULFATE AND FERROUS SULFATE/ BUT IN TIME DIFFERENCES BETWEEN THE SOLUTIONS BECAME APPARENT. MICROSCOPIC EXAMINATION OF THE THIN SECTIONS SHOWED GYPSUM AS THE PREDOMINANT SULFATE REACTION PRODUCT. ETTRINGITE WAS FOUND PREDOMINANTLY IN SPECIMENS THAT HAD BEEN STORED IN SODIUM SULFATE. THE FOLLOWING CONCLUSIONS ARE DRAWN' /1/ THE AGGRESSIVENESS OF THE SOLUTIONS INCREASES FROM SODIUM SULFATE, OVER MAGNESIUM SULFATE, TO FERROUS SULFATE, /2/ THE RESISTANCE OF THE CEMENT PASTE CAN BE IMPROVED BY INCREASING ITS DENSITY, AND /3/ THIN-SECTION EXAMINATIONS SHOW THAT ETTRINGITE IS RARELY FORMED IN SUFFICIENT QUANTITIES TO CAUSE CRACK FORMATIONS. REFERENCES' THE DETERMINATION OF NONEVAPORABLE WATER IN HARDENED PORTLAND CEMENT PASTE, L. E. COPELAND, J. C. HAYES, ASTM BULL, V. 194, PP 70-74, 1953.