内养护混凝土复合溶液下的耐酸腐蚀性能

Resistance to acid attack of internal curing concrete under complex solutions

采用预湿粉煤灰陶砂作为轻细骨料取代混凝土中的部分砂和石子,额外的引入水量可以完全消除混凝土自收缩以起到内养护的效果。通过室内加速腐蚀试验,研究了水灰比为0.36的内养护混凝土和普通混凝土在盐酸溶液(pH=2、4)、盐溶液(6%NaCl)、酸和盐的复合溶液(6%NaCl,pH=2、4)侵蚀后,抗压强度随时间的变化规律及原因。试验结果表明,在相同的腐蚀试验条件下,内养护混凝土的耐酸性腐蚀性能优于普通混凝土。同时发现,复合溶液对混凝土的劣化作用大于相同pH值的盐酸溶液,腐蚀过程中H^+和Cl^-的侵蚀是双重的,溶液的侵蚀速率不仅取决于H^+浓度,也与Cl^-浓度有关。微观结构观测表明,轻细骨料与浆体的界面过渡区致密均匀,因此其替代了大量薄弱的普通骨料界面过渡区有利于改善混凝土的抗渗透性。并且内养护技术在收缩调控、抗开裂性能上具有显著优势,对耐酸腐蚀性能有积极影响。

This study uses prewetted sintered fly-ash aggregate as additives to replace part of the fine aggregate.The internal curing water from the lightweight aggregate is sufficient to mitigate autogenous shrinkage.A W/C of 0.36 normal and internally cured concretes have been investigated for strength reduction under the acid environments of pH=2 or 4 with and without NaCl.It was found that the internally cured concrete performs well than the normal concrete in terms of acid resistance.And the complex solution causes more damage to concrete than the acid solution alone,due to the double damages from H^＋ and Cl^- in complex solution.The ITZ between lightweight aggregate and the matrix is more dense than that between normal aggregate and the matrix,and thus improves the permeability resistance.