Time and cold joint effect on chloride diffusion in concrete containing GGBFS under various loading conditions

摘要

The stress due to volume change causes cracking in concrete, so that construction joint is intentionally prepared for an efficient construction and crack controlling in mass concrete structure. Cold joint means a weak joint area which may occur due to imperfect treatment of pre-placed concrete surface and delayed concrete delivery. Many researches have been performed for a quantitative evaluation of chloride ingress in cold joint concrete, which puts an emphasis on the more rapid penetration of chloride ions. The applied loading condition is one of the major reasons for concrete cracking and it also has a great effect on chloride penetration before the stage of cracking. Steel corrosion in concrete is accelerated when concrete cover has unsound area such as crack and cold joint. Chloride diffusion behavior varies with reduction of porosity and enhancement of hydrates, so called time effect on chloride diffusion. The effect of time and of cold joint on chloride diffusion is an important parameter for quantitative durability design for RC (Reinforced Concrete) structures exposed to various loading conditions.