Abstract
Insufficient cover thickness of concrete can cause corrosion of reinforcements in concrete members at earlier age. This earlier deterioration, such as carbonation and salt damage, is sometimes caused by enlargement of water-cement ratio at surface part of concrete cast in impermeable wooden sheaths used in general concrete works. However, this non-uniformity of water-cement ratio in concrete members is not considered in the standard specifications. Therefore, a design method for "effective cover thickness" was proposed. The effective cover thickness, considering this non-uniformity in concrete, was defined as the cover that could be evaluated to obtain equivalent durability, using uniformity of concrete. The effective cover thickness could be evaluated by the coefficient of carbonation rate and the diffusion coefficient of chloride content determined by the profile of water-cement ratio in concrete members. As a result of the evaluation, deterioration of concrete could be accelerated as cover thickness was thinner and water-cement ratio was larger.
