Which type of soil is classified as Type A?

Type A soil is characterized by its high unconfined compressive strength, specifically having strengths of 1.5 tons per square foot (tsf) or greater. This classification typically aligns with cohesive soils, such as clay, which exhibit strength and stability and are less likely to fail under stress compared to other soil types. The designation of Type A is vital in various construction and engineering applications, particularly related to excavation safety where the structural integrity of soil is paramount.

In contrast, other classifications involve soils with lower strength or that possess different physical characteristics. For example, soils with unconfined compressive strength of 0.5 tsf or that crumble easily when dry typically fall under Type B or C classifications, which denote a higher risk of collapse and a lower strength. Therefore, the correct classification of Type A as those with a compressive strength of 1.5 tsf or greater emphasizes their solidity and stability in engineering contexts.