General Contractor Practice Exam

What type of material should be used as backfill after concrete forms are removed?

1. Aggressive clay

2. Organic material

3. Gravel

4. Sand only

The correct answer is: Gravel

Using gravel as backfill after removing concrete forms is a preferred practice due to its excellent drainage properties and stability. Gravel allows water to flow freely, minimizing the risk of hydrostatic pressure building up against the concrete structure. This is particularly important because excessive moisture can weaken a foundation and lead to long-term structural issues. In addition, gravel compacts well, providing good support around the concrete. It creates a solid base that helps distribute weight evenly and reduces the chances of settling over time. The coarse nature of gravel also helps prevent erosion and promotes a more consistent load-bearing capacity, which is essential for the durability of the construction. Other materials like aggressive clay and organic material can cause problems when used as backfill. Aggressive clay can expand and contract with moisture, leading to instability in surrounding structures. Organic material can decompose over time, resulting in settling and voids that compromise the integrity of the foundation. Using sand alone may be insufficient as it does not provide the same level of structural support and may not drain water effectively on its own. Therefore, gravel is the most suitable choice for backfill in this scenario.