PROPERTIES OF CONCRETE INCORPORATING A HIGH-RESISTANCE ADMIXTURE FOR CHLORIDE ATTACK

Abstract

Concrete structures in coastal and snowy regions are generally subjected to salt-attack, so these concrete are required for the high resistance to chloride-ion penetration. To improve durability of concrete structures exposed to such severe environments, the authors have developed a pozzolanic admixture having excellent resistance to chloride attack. The admixture is a mineral fine powder with a BET specific surface area of 13m²/g or higher. The powder material（general mixture of 6.5 to 13％）can be used as an alternative binder of Portland cement like other cementitious materials. The present research focuses on the properties and durability of concrete cured in the standard condition to examine the applicability of the admixture to general ready-mixed concrete. The experimental study examined various properties of the concrete incorporating the admixture, such as the chloride penetration resistance；compressive strength；drying shrinkage；freeze-thaw resistance and carbonation. In addition, pore distribution of the concrete was investigated to confirm the effect of the powder material. The test result showed that the admixture（6.5 to 13％ as alternative cementitious material）contributes to decrease of effective diffusion coefficient of chloride ion. The observation in pore distribution confirmed the increase of pore volume of 0.01μm（or smaller）in concrete, hence the improvement effects of chloride resistance and other durability were confirmed.