Massachusetts Unrestricted Construction Supervisor License Practice Test

Which foundation material has the greatest allowable bearing pressure?

1. Foliated bedrock - slate

2. Dense gravel

3. Stiff silty clay

4. Dense glacial till

The correct answer is: Dense gravel

Dense gravel is widely recognized for having the greatest allowable bearing pressure among the listed foundation materials. The reason for this is due to its granular composition, which allows for effective weight distribution. Dense gravel has high shear strength and is capable of supporting heavy loads, making it an excellent choice for foundations that require substantial support. When compared to the other materials, dense gravel's structure facilitates quick drainage, reducing the risk of water accumulation that can undermine stability. While foliation in slate bedrock can offer decent support, it often has variations in strength due to natural fissures and weaknesses. Stiff silty clay, although providing some stability, can be less reliable under certain moisture conditions, which can lead to reduced bearing capacity over time. Lastly, dense glacial till, while also a strong material, typically has less overall bearing capacity than dense gravel when considering different applications in construction. Therefore, when assessing the allowable bearing pressures of these materials, dense gravel stands out as the most robust option for foundational support.