Load-bearing Capacity of Corroded Reinforced Concrete Structures Caused by Carbonation and Exposed to XC4

Concrete corrosion can be visualized as a combination of chemical reaction on concrete and electrochemical reaction on steel reinforcement. Failure of steel reinforcement due to corrosion can inflict significant stress on concrete during load distribution. As such, it is necessary to analyse the long-term effects of corrosion on the load bearing capascity and bending strength of steel reinforcement. This research investigated the mechanical and electrochemical properties of concrete exposed to long-term corrosion for a period of 16 years. Non-destructive testing like crack width measurements, visual examination, electrochemical measurements using Galva Pulse and determination of average chloride content were undertaken to identify the state of corrosion and to ascertain the impact of corrosion on the chemical properties of concrete. Further testing included mechanical test for load-bearing capacity and compressive strength. The electrochemical measurement results signified the condition of the corroded beam specimens and provided the degree of corrosion at the time of experimentation. Beam specimens with large crack widths, and reinforcement bar diameters showed poor resistance to corrosion. Load-bearing capacities of above mentioned corroded beam specimens were lower when compared to the original measurements before exposure started. The reason was the reduction in cement-steel bonding due to the expansion of rust in the structure. However, compressive strength of concrete almost doubled due to continuous hydration occurring during the cyclic wetting and drying period. This increase in compressive strength of concrete compensated the reduction in load-bearing capacity.