Effect of Sea Water on Portland Cement Type I and V Concretes Containing Fly Ash from Fluidized Bed Combustion

Abstract

This research aimed to study the effect of cement type I and V blended fly ash from fluidized bedcombustion on compressive strength, chloride penetration, and corrosion of steel in concrete undermarine exposure. Portland cement type I and V were used to cast concrete. Water to binder ratio was keptconstant at 0.65. Fly ash was ground to have particles as retained on a sieve No. 325 of 2% by weight andthen was used as a partial replacement of Portland cement type I and V at 0, 15, 25, 35 and 50% byweight of binder. The 200-mm concrete cube specimens with steel bar of 12-mm in diameter and 50-mmin length embedded at the cover depth of 20 and 50 mm were cast. Concrete specimens were cured infresh water for 27 days, and then were placed to expose tidal zone of sea water at wet-dry condition.Compressive strength, chloride penetration, and rusted area of steel in concrete at the age of 1 year ofexposure in sea water were investigated.

The results illustrated that the compressive strength of exposed concrete in sea water was slightlylower than that of concrete cured in fresh water. Fly ash concrete provided better resistance of chlorideingress than the one without fly ash. The increase in fly ash replacement in both of Portland cement typeI and V concretes could reduce the chloride ingress and steel corrosion. In addition, Portland cement typeI concrete containing fly ash had slightly higher chloride ingress than Portland cement type V concretecontaining fly ash. However, the results of corrosion of steel bars were not different from both concretes.