Effect of Quality of Surface Layer of Concrete on Scaling Resistance

(1)混凝土的冻害机理研究了混凝土的冻害机理.按6种类型对结垢机理进行了分类。它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)混凝土结构的实际冻害状况通过问卷调查了东北地区混凝土的实际冻害状况。考虑了冻害的恶化症状、地区、人员、时间、原因、冻害的修复以及除冰盐的撒布量。(3)混凝土表层质量对抗结垢性能的影响认为氯化物操作时发生的热冲击影响结垢。在保证混凝土表面孔结构和强度的固定值的情况下，可以增加抗垢性。然而，含水量的影响大于孔结构和强度的事实被证实。(4)不同粗集料混凝土的抗结垢性能在一定水灰比和含气量的条件下，低质量集料和粉煤灰人工集料混凝土的抗结垢性能得到提高。然而，混凝土的剥落损伤不能仅仅从骨料的密度和含水率来估计。(5)蒸汽养护混凝土的抗结垢性在蒸汽养护混凝土中混合所需的空气含量时，结垢量减少，即使改变各种制造条件，也未证实结垢量的显著差异。因此，认为掺入所需的含气量对保证蒸养混凝土的抗剥落性能至关重要。

(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.