Abstract
A structural fragile layer is formed in the surface layer of concrete by the influence of the bleeding of fresh concrete and the environmental conditions. This fragile layer formed to the surface layer of concrete causes the difference in quality between the surface layer of concrete and the inside part of concrete. Authors aimed to the thickness of member section of a concrete material as the factor that influenced the formation of a fragile layer, and examined it experimentally. In this study, to examine the influence that the difference of the thickness of member section of concrete material exerted on the result of the durability, the test for bleeding of fresh concrete, rebound number test, the scaling test and the accelerated carbonation test were executed. Authors clarified the following from the results of an experimental examination. 1. The amount of the bleeding of fresh concrete that becomes the factor of the formation of a fragile layer was increased as the member section increases. 2. An increase in the amount of the bleeding of fresh concrete becomes remarkable near the formwork. 3. The scaling resistance and the material movement resistance decrease as the thickness of member section of specimen increases. As a result, authors clarified that durability of concrete changed greatly by the difference of the thickness of member section of concrete.
