コンクリートの凍害におけるひびわれの役割の考察

抄録

The amount and extent of the cracks observed on the surface of concrete were measured by using test specimens exposed to the outdoors in Sapporo for 20 years. The process of the crack formation caused by frost action was discussed based on the measurements, with use of former results of freezing and thawing tests which were carried out in order to explain the influence of craek formation on frost deterioration of concrete. The following conclusions regarding the role of these cracks on frost damage of concrete seem to be reasonable. (1) Visible cracks observed on the surface of concrete are caused by the expansion of the interior and not by the direct action of the freezing and thawing. (2) The acceleration of frost damage derived from the cracks mainly arises from the penetration of water into the concrete from the surface. (3) The action, which enlarges cracks during the freezing process, does not play a too significant role in frost damage of concrete.