Low durability of concrete elements due to steel corrosion - cases wherein the steel reinforcing bars acted as an internal clock bomb

Concrete elements are expected to resist any process of deterioration to remain its original form, quality and serviceability when exposed to its intended service environment. As the concrete deteriorates durability problems progressively develop leading to structural damage, which might put users in a potential danger. Concrete deterioration may be categorized into three categories of causes: physical, chemical, and mechanical, from which major durability issues come from steel corrosion as a result of combined effect of multi environmental factors. This work reports examples wherein the corrosion of the steel reinforcing bars severely affected the concrete element durability. Five examples wherein the steel reinforcing bars got prematurely corroded, acting as an internal clock bomb for concrete element durability, are reported. It is questioned if the steel reinforcing bars were structurally (un)necessary and if (in)appropriate construction practices were used. Alternative solutions for higher durability are proposed.