The in situ field density and water content of soil and soil-aggregate base materials are critical parameters that affect the stability and performance of pavements, foundations, and other structures built on these materials. The test methods described in ASTM D4546-21 provide a means of determining these parameters in the field, allowing for the evaluation of the material's suitability for construction.

If an engineer designs a slab-on-grade foundation without knowing the Swell Pressure, they risk the foundation lifting differentially. By quantifying the pressure, engineers can design or deep foundations (piers) that extend below the active zone of moisture fluctuation.