Effect of Quality of Surface Layer of Concrete on Scaling Resistance

(1)冻害机理在参考文献的基础上，对混凝土的冻害机理进行了研究。缩放机制分为 6 种类型。认为这些机制实际上是复合的，并且某些机制在某些情况下表现出色，并且结垢发展。(2)混凝土结构冻害的实际状况通过问卷调查对东北地区混凝土冻害的实际状况进行了调查。考虑了冻害的劣化症状、面积、构件、时间、原因和修复以及除冰剂盐的撒播量。(3)混凝土表层质量对抗结垢性的影响假设氯化物操作时发生的热冲击影响结垢。可以增加抗结垢性，以确保孔结构和混凝土表面强度的固定值。然而，水含量的影响大于孔隙结构和强度的事实得到了证实。(4)含有各种粗骨料的混凝土的抗结垢性在保证一定的水灰比和含气量的情况下，含有劣质骨料或粉煤灰人工骨料的混凝土的抗结垢性得到改善。然而，仅根据骨料的密度和含水率并不能估计混凝土的结垢损坏。（5）蒸养混凝土的抗结垢性能当在蒸养混凝土中掺入所需的空气含量时，结垢量下降，即使改变各种制造条件，也未确认结垢量存在显着差异。因此，认为掺入所需的空气含量对于保证蒸养混凝土的抗结垢性能非常重要。

(1) Mechanism of frost damageThe mechanism of frost damage of concrete was investigated from the reference. The mechanism of the scaling was put in order by 6 types. It thought that these mechanisms were compound actually, and that some of the mechanisms excelled in some case and that the scaling developed.(2) Actual state of frost damage at the concrete structuresThe actual state of frost damage of concrete at the Tohoku district was investigated by the questionnaire. Deterioration symptom, area, members, time, causes, and repair of the frost damage, and the spreading amount of deicer salts were considered.(3) Effect of quality of surface layer of concrete on scaling resistanceIt supposed that the thermal shock which occurs in case of the chloride operation influenced a scaling. Scaling resistance can be increased in securing to fixed value in the pore structure and the strength of the concrete surface. However, the fact that the influence of the water content is larger than the pore structure and the strength was confirmed.(4) Scaling resistance of concrete containing various coarse aggregatesThe scaling resistance of the concrete containing low-quality aggregates or fly ash artificial aggregates was improved when securing fixed water cement ratio and air content. However, scaling damage of concrete could not be estimated solely from the density and the moisture content of aggregates.(5) Scaling resistance of steam-cured concreteWhen mixing required air content in steam-cured concrete, the scaling amount decreased and even if various manufacturing conditions were changed, differences with remarkable scaling amount were not confirmed. Therefore, it supposed that to mix required air content was very important to secure the scaling resistance of steam-cured concrete.