Abstract
Chloride permeability of concrete is one of the major factors that influence the corrosion of steel reinforcement in concrete. It has been confirmed that the chloride permeability of cement paste and mortar varies widely depending on the water: cement ratio, type of cement, curing condition and so on. However, there are only a few reports concerning the chloride permeability of concrete. This study aims at revealing the effect of curing condition on the chloride permeability of concrete in which Portland cement was replaced in various amounts by flyash and blastfurnace slag. The chloride permeability of concrete was determined by the accelerated chloride permeability test using a diffusion cell similar to that described in Federal Highway Administration report (FHWA/RD-81/119). In order to relate the porosity or pore size distribution of concrete to its chloride permeability, the mercury intrusion porosimetry measurements were also conducted.
The experimental results showed that the chloride permeability of concrete containing flyash and blastfurnace slag was high when the concrete was exposed to a low humidity at the early stage of curing. It was also found that the chloride permeability of concrete increased proportionally with increasing volume of pores larger than 0.1μm in diameter.
