Chloride Diffusivity and Corrosion Resistance of OPC-MK-RM based Ternary Blended Concrete - An Experimental Investigation

Abstract

This paper reports the results of the investigation on chloride migration diffusion coefficient and corrosion resistance of metakaolin (MK) and redmud (RM) blended cement concrete with various replacement levels. The concrete had 0% to 14% of metakaolin and redmud as cement replacement separately and with different proportions of metakaolin:redmud (50:50, 60:40, 70:30 and 80:20). The concrete had prepared with water/binder ratios of 0.40, 0.38 0.36 and 0.33. The rapid chloride penetration test (RCPT) was used to calculate the chloride ion (Cl-) diffusion coefficient (DC) of concrete using the Berke's equation for steady state condition. Corrosion of embedded steel bars in concrete was measured by conducting accelerated corrosion test. The results shows that replacement of metakaolin and redmud was increased the charged passed and diffusion coefficient were digressed. Similar trend was observed in all w/b ratios of concrete blend with different metakaolin:redmud (MK:RM). The percentage loss of weight of embedded steel was lower as percentage of replacement of metakaolin and redmud increased. The concrete of lower w/b ratio has higher value of percentage of loss in weight when compared to concrete which has higher w/b ratio in all replacement levels. In all w/b ratios with percentage replacement of combination of MK:RM, the percentage loss in weight was lower in the proportion of 50:50 compared to 80:20. The results show that the careful choice of composition can reduce the corrosion rate of reinforced steel in concrete.