Why is asphalt-impregnated fiber board unsuitable for concrete ringwall foundations?

• A. It is too expensive
• B. It deteriorates and allows moisture to enter
• C. It is not durable enough for heavy loads
• D. It does not provide a flat surface

Answer: (B)

Asphalt-impregnated fiber board is unsuitable for concrete ringwall foundations primarily because it deteriorates and allows moisture to enter. When used in applications involving foundations, the integrity of the materials is critical to ensure that the structure is stable and moisture-free. Over time, exposure to moisture can lead to the breakdown of the fiber board, compromising its ability to provide proper support and insulation. As the material deteriorates, it can create pathways for moisture infiltration, which is particularly problematic in a concrete foundation, leading to potential structural issues, such as cracking or weakening of the concrete due to water damage.

In contrast, other factors such as cost, durability under heavy loads, and surface flatness are also important considerations; however, the primary concern with asphalt-impregnated fiber board is its susceptibility to moisture. This characteristic directly impacts the long-term performance and safety of the tank, making it unsuitable in this context.