Authors: Sakkarin Pavitpok and Taweechai Sumranwanich
In this study, chloride diffusion coefficient and compressive strength of concrete with interground fly ash cement and blast-furnace slag cement under marine environment of Thailand were investigated. Water-to-binder (w/b) ratios of concrete were used at 0.40, 0.50 and 0.60. The 200x200x200 mm3 concrete cube specimens were cast and steel rebar of 12-mm in diameter and 50-mm in length were embedded with covering depths of 10, 20, 50, and 75 mm. Concrete specimens were cured in water for 28 days and then were exposed in the tidal zone. After 7-year of marine exposure, the specimens were collected and tested for total chloride penetration and compressive strength. The steel bars insides the specimens at different covering depth were measured for weight loss due to steel corrosion. The results showed that concrete with interground fly ash and blast-furnace slag cements have better resistance to chloride penetration than the concrete with ordinary Portland cement (OPC). The chloride penetration was decreased with the decreasing of w/b ratio. The corrosion of steel bars in blastfurnace slag concrete was lower than that of steel bars in interground fly ash and ordinary Portland concretes. Blastfurnace slag concrete having w/b ratio of 0.60 provided better corrosion resistance than the ordinary Portland concrete with w/b ratio of 0.40 at more than 2 cm covering depth of concrete. In addition, chloride diffusion coefficient of concrete containing blast-furnace slag cement was the lowest among all concrete mixes.
Keywords: Chloride diffusion coefficient; Compressive strength; Marine environment; Interground fly ash cement; Blast-furnace slag cement.