Corrosion Protection: How Much Concrete Cover Is Enough?

Environmental and chemical elements are concrete and rebar steel’s enemies when it comes to corrosion. Spalling and efflorescence, salt decay from evaporated moisture can lurk inside a concrete surface and break down the material. Hail, rain, and winter conditions can provide not only elemental stress and moisture, but some of the salt chemical as well. Aside from surface penetrating sealants, and rebar reinforcement bars, these two detriments are unavoidable. Concrete cover can help prolong reinforcement life by keeping it free from these damaging conditions. But for the issue of embedding steel into concrete, how much cover is enough?

Concrete Cover

The purpose of concrete cover is multi-fold; to protect reinforcement materials from the environment, as well as fire, and to provide a large enough embedding space to minimize slipping stress. There are many different concrete codes when it comes to cover measurements for different countries. For example, East Indian codes suggest a nominal cover range from mild to extreme exposure conditions from 20-75mm. American codes suggest 40-50mm. Weather conditions range from country to country, with northern areas being affected by harsh winter stresses.

Caution and accuracy should be exercised here, since too much concrete cover will increase a surface’s chances of cracking. Larger crack widths allow more moisture and chemical infiltration, leading to quicker and more damaging corrosion issues for both the concrete and the rebar. Visual results of not enough cover are obvious when the ridged steel bars can be seen through the concrete surface, or worse, poking right out. This leaves the steel vulnerable to rust, diminishing the job it was embedded to do.