North Carolina Building Contractor License Practice Exam

What common issue can arise in concrete if soluble salts are present?

1. Cracking

2. Efflorescence

3. Spalling

4. Discoloration

The correct answer is: Efflorescence

Efflorescence is a common issue that occurs in concrete when soluble salts are present. When concrete is exposed to moisture, the water can dissolve these salts, which then migrate to the surface as the moisture evaporates. Once the water evaporates, the soluble salts are left behind, forming a white, powdery residue on the surface of the concrete. This phenomenon can affect the aesthetic appearance of the concrete and may also indicate underlying moisture problems. Understanding efflorescence is important for contractors because it can signal issues with water intrusion or inadequate drainage around a structure. While it may not compromise the structural integrity of the concrete, the presence of efflorescence can lead to further problems if moisture accumulation is not addressed, making it critical for builders to recognize and manage the factors that contribute to this condition.