General Contractor Practice Exam

How much concrete should cover #4 rebar that is exposed to earth?

1. 1 inch

2. 1 1/2 inch

3. 2 inches

4. 2 1/2 inches

The correct answer is: 1 1/2 inch

When rebar is exposed to earth, it is crucial to ensure that there is an adequate amount of concrete cover to protect the rebar from corrosion and other environmental factors. The correct answer specifies a concrete cover of 1 1/2 inches for #4 rebar, which aligns with the standards outlined in building codes such as the American Concrete Institute (ACI) guidelines. These guidelines indicate that for concrete members exposed to soil or backfill, the minimum cover required is often set at 1.5 inches. This requirement ensures that the rebar remains sufficiently protected from moisture and chemical reactions in the soil that could lead to corrosion over time. Additionally, this thickness provides structural integrity and helps maintain the bond between the concrete and the rebar. The other choices suggest varying amounts of cover that exceed the minimum requirement; however, the standard of 1 1/2 inches is specifically intended for general situations involving soil contact. This balance supports both protection and structural efficiency, adhering to best practices in concrete construction.