General Contractor Practice Exam

Which material is commonly used as a base layer before pouring concrete?

1. Clay

2. Gravel

3. Sand

4. Asphalt

The correct answer is: Gravel

Gravel is commonly used as a base layer before pouring concrete for several important reasons. First, it provides excellent drainage, preventing water from pooling under the concrete slab. Proper drainage helps reduce the risk of erosion and potential cracking that can result from moisture accumulation. Gravel also creates a stable and supportive foundation, allowing for even weight distribution across the concrete. This stability is essential in preventing settling and ensuring the longevity of the concrete structure. Additionally, the angular shape of gravel particles interlocks, providing superior load-bearing capabilities compared to other materials. This characteristic helps the base layer resist movement, thereby minimizing shifts that could compromise the integrity of the poured concrete above it. Overall, using gravel as a base layer enhances the performance of the concrete slab, resulting in a durable and reliable surface.