Corrosion Prevention And Control Practice Test

Reinforcement corrosion in concrete mainly happens through two pathways: carbonation and chloride ingress. Carbonation occurs when carbon dioxide from the air reacts with calcium hydroxide in the concrete, lowering the pore solution pH and destroying the protective passive oxide film on steel. Chloride ingress comes from salts (like de-icing salts or seawater) and diffuses into the concrete, depassivating the steel and enabling corrosion, often starting at cracks or moisture-filled pores. Mitigation rests on blocking or slowing both pathways and keeping the steel protected. Adequate cover depth and good detailing limit how quickly CO2 and chlorides can reach the steel. Using low-permeability, dense concrete (often with supplementary cementitious materials) slows ingress. Sealing exposed surfaces and joints reduces pathways for moisture and chlorides. Corrosion inhibitors can provide additional protection, and proper curing helps prevent cracking that would create shortcuts for ingress. In high-chloride environments, employing corrosion-resistant reinforcement or protective coatings, or cathodic protection, may be warranted. This is why the option recognizing both carbonation and chloride ingress and listing measures like adequate cover, low-permeability concrete, sealants, corrosion inhibitors, and proper detailing is the best choice. Focusing on only one mechanism or denying that concrete can corrode reinforcement misses the reality of how deterioration occurs.