There is disclosed a method of selecting, in real time, a soil stabilizing protocol for clay-bearing soils occurring in construction sites. The method includes the steps of: obtaining soil conductivity data values at locations within a defined site without disturbing the surface of the soil; correlating the soil conductivity data values with corresponding estimates of soluble sulfate levels; recommending a calcium-based soil stabilizing protocol if the estimated level of soluble sulfates is less than a predetermined threshold; and performing a laboratory analysis of soil samples from selected portions of the defined site when the estimated soluble sulfate concentration equals or exceeds the predetermined threshold.