Concrete cover is essential for protecting reinforcing steel from corrosion caused by environmental factors. Steel reinforcement will corrode due to oxidation if it is not properly placed or protected from the environment. Reinforcing steel frequently oxidizes as a result of moisture penetration or carbon dioxide intrusion through the concrete. When steel reinforcement corrodes, it rusts and expands to a greater volume than the steel itself. As a result of this motion, the concrete covering the steel begins to crack, spall, and delaminate. The longer it takes for carbon dioxide or moisture to enter, the more concrete protection is provided.
Although the concrete cover shields the reinforcement from the elements, it also safeguards the reinforcement during a fire. Extreme surface temperatures, surpassing 1500° F, are possible for concrete. However, when exposed to temperatures above 1200° F, reinforcing steel will lose 50% of its steel strength.
Concrete cover is essential for keeping reinforcing steel cooler than outside elements, and the thicker the concrete cover, the greater the fire rating that’s achieved.
The bond strength between the concrete and the reinforcing steel is crucial to reinforced concrete design. Tensile stresses must be transferred from concrete to its reinforcing steel in order to prevent failures. For the link between concrete and steel to be strong, the reinforcing steel must be covered with concrete. The binding strength and slide resistance between the materials are also strengthened by adding more concrete cover.
Failures will continue to occur if insufficient cover is left in place, costing an owner more time and money and causing them more frustration.