Civil Engineering - Soil Mechanics and Foundation Engineering - Discussion

Silty clay loam should contain highest percentage of clay and not silt. Hence B can't be true.

Loam-mixture of sand silt clay of approx equal proportion.

Sandy clay loam: 20 to 35 per cent clay, less than 28 per cent silt, and 45 per cent or more sand.

Silty clay loam: 27 to 40 per cent clay and less than 20 per cent sand.

It's all of the above.

Loam means equal percentage of sand silt and clay fraction. So loam is not correct. Option C is stiff boulder clay it may be rite but the boulder is not clay. I think the correct answer is option D.

The correct statement is C. Stiff boulder clay offers maximum shear strength.

Explanation.

Stiff boulder clay offers maximum shear strength. Boulder clay (or till) is a highly variable, unsorted mixture of different sediment sizes in a stiff, fine-grained matrix. Its stiffness, density, and mixed composition contribute to its high shear strength, making it a very stable material.

Why are other options incorrect?

Sandy clay loam contains the highest percentage of sand. The soil with the highest percentage of sand (85% or more) is classified simply as sand or sandy soil, not sandy clay loam. A sandy clay loam has a high percentage of sand, but other soil types like sandy loam or sand have higher proportions.

Silty clay loam contains the highest percentage of silt: A soil classified as silt or silt loam generally contains a higher percentage of silt than silty clay loam, which also contains a significant percentage of clay.

Soft chalk carries the least safe load: While soft chalk has a low bearing capacity compared to some other rocks/soils, other materials like very soft, sensitive clays or peat may carry an even smaller safe load, and chalk itself is a type of rock, generally stronger than unconsolidated soils. Stiff boulder clay is known for its high bearing capacity.