Using cellular concrete produced with the Aerix family of foam liquid concentrates is fitting for subgrade modification when existing soils are undesirable for construction. As an alternative to over excavating and replacing poor soils with better soil, a layer of cellular lightweight concrete placed over the poor soils will reduce vertical deadloads, and increase bearing capacity and stability with the addition of minimal weight. The layer of cellular concrete also reduces settlement potential, improves stability in seismic areas, and provides insulating qualities.