An operator is excavating a trench for a pipeline in cohesive soil. During excavation, the soil crumbles into defined blocks and exhibits moderate plasticity when wet. Which soil classification best describes this material according to common geotechnical practice?

Question: An operator is excavating a trench for a pipeline in cohesive soil. During excavation, the soil crumbles into defined blocks and exhibits moderate plasticity when wet. Which soil classification best describes this material according to common geotechnical practice?

Answer options:

• Silt
• Sand ✅ Clay
• Gravel

Correct answer: Clay

Explanation: Cohesive soils that crumble into blocks and exhibit plasticity when wet are characteristic properties of clay. Clay particles are very fine and stick together, distinguishing them from granular soils like sand or gravel.