Effect of addition of sugarcane baggasse ash on half-cell potential of cathodically protected RCC structures subjected to chloride ingress

Abstract

Sugar cane bagasse ash (SCBA) is a by-product generated from sugar boilers and alcohol factories. It mainly consists of amorphous silica, which makes it a suitable supplementary cementitious material (SCM), apart from providing an economically viable and environmentally sustainable solution. This is particularly true in Indian scenario, which is second largest producer of sugarcane. Ample literature is available which describe the strength and durability aspects of concrete containing SCBA. But, less literature is available on corrosion behavior of such concrete. In the present research, the effect of partial cement replacement by SCBA on the half cell potential (HCP) of reinforcements embedded in concrete is studied through twelve reinforced concrete slabs made of M20 grade and dimension 1000 mm X1000 mm X100 mm. The amount of SCBA in each slab was 20% by weight of cement, based on obtained experimental results of compressive and flexural strengths at 7, 28, 56 and 90 days. All the slabs were cathodically protected using pure Magnesium (Mg) anodes. Out of the twelve slabs, six slabs were subjected to 3.5% NaCl ingress while the remaining six acted as reference slabs with no chloride ions. The HCP were measured at 80 points on each slab for 280 days, to observe the trend of these values and were averaged for similar slabs. It could be concluded that the presence of SCBA significantly reduces the HCP values, thereby indicating lesser probability of corrosion. The HCP values were higher for slabs containing chloride ions. Thus, for structures subjected to marine atmosphere, a combination of incorporating SCBA and cathodic protection could be an effective solution to mitigate corrosion.