Effect of Locally Sourced Pozzolan on Corrosion Resistance of Steel in Reinforced Concrete Beams

Abstract

Corrosion of the reinforcing steel in concrete continues to be a major cause of damage to reinforced concrete (RC) structures. Eight reinforced concrete beams with dimensions of 100 mm by 150 mm in cross-section and 1000 mm in length were divided into two groups. For each group, locally sourced fly ash was used to partially replace the ordinary Portland cement in the proportions of 0% (control samples), 10%, 20% and 40% by weight. The reinforcing steel bars were weighed and then, after casting and curing, were subjected to accelerated corrosion by employing an anodic impressed voltage at 10 V DC (Group 1) and 20 V DC (Group 2) for 377 h (16 days). The beams were then flexurally tested and the reinforcing steel bars were removed, cleaned and re-weighed to determine the extent of corrosion. The results demonstrate that the Vietnamese-sourced fly ash significantly increases the corrosion resistance of the reinforcing steel with higher fly ash replacement providing better corrosion resistance. The flexural strength of the pre-corroded reinforced concrete beams with partial cement replacement by fly ash is increased by up to 16% for Group 1 and 120% for Group 2. The fly ash was also found to increase the ductility of the pre-corroded reinforced concrete beams.