Compaction causes

• A. An increase in unit weight, decrease in compressibility and permeability.
• B. Decrease in unit weight, increase in compressibility.
• C. No change in physical properties.
• D. Increase in permeability but decrease in unit weight.

Answer: (A)

Compaction densifies the soil by packing particles more tightly and squeezing out air, which raises the dry unit weight. With fewer voids and a denser structure, the soil becomes stiffer and less able to compress further under load, so compressibility decreases. The reduced pore spaces also restrict water flow, causing permeability to drop. So, the scenario that describes an increase in unit weight along with decreases in both compressibility and permeability matches what compaction does in earthwork.