Influence of Rebar Configuration and Reservoir Size on Corrosion Dynamics in Fly Ash Concrete: A Galvanostatic Pulse Study

Abstract

This study investigates corrosion propagation in fly ash (FA) concrete with single rebar and three rebars, prepared using a w/cm ratio of 0.41. Accelerated chloride transport was achieved through electromigration approach. Corrosion initiation was detected at a rebar potential of -150 mV vs. saturated calomel electrode (SCE), while propagation was evaluated using galvanostatic pulse (GP) measurements. Throughout 300–1600 days, the size of the reservoir had a notable impact on corrosion current behavior. The larger reservoirs showed a steady decrease in corrosion current values, while smaller reservoirs had lower but more variable corrosion current values. The intermediate reservoirs (7.5 cm) showed the highest corrosion activity among the single rebar samples, likely due to balanced oxygen and moisture levels. The three rebar samples experienced higher corrosion currents, more negative potentials, and greater susceptibility to corrosion. The renewed corrosion activity on some selected samples after 1400 days suggests passive layer breakdown, highlighting the role of reservoir size, rebar configuration, and environmental factors in FA concrete durability.