ML classification refers to which material property?

• A. High plastic clay with low porosity
• B. High density stone with low porosity
• C. Low plastic sandstone with high permeability
• D. Low plastic silt, high porosity but low permeability

Answer: (D)

ML classification is about how a material conducts fluids, essentially its permeability. Porosity measures how much void space exists, but permeability depends on how well those voids are connected. A low-plasticity silt can have high porosity, yet the pore spaces may be poorly connected, resulting in low permeability. That combination—high porosity with low permeability—fits what ML classification is assessing. The material’s plasticity or density isn’t the focus for ML classification, and assuming high flow from high porosity would be incorrect due to pore connectivity effects.