General Contractor Practice Exam

What is the recommended time for removing forms from cast-in-place concrete?

1. 12 hours

2. 24 hours

3. 48 hours

4. 72 hours

The correct answer is: 24 hours

The recommended time for removing forms from cast-in-place concrete is around 24 hours. This timeframe is based on the curing process of the concrete and the development of its initial strength. After pouring concrete, it begins to hydrate and gain strength due to the chemical reactions between water and the cement. In the first 24 hours, the concrete should typically reach sufficient stiffness to support its own weight and the load of the formwork. Removing forms too early can compromise the concrete's strength and lead to surface defects, while leaving them on too long can result in difficulty removing forms or even damage to the concrete surface. Factors such as the mix design, environmental conditions, and specific project requirements can influence this timing, but 24 hours generally provides a good balance for optimal finishing and structural integrity.