Definition of Expansion Potential for Expansive Soils

Abstract: Expansion potential of an expansive soil is most commonly expressed in terms of the amount of swelling that occurs during inundation in the consolidation-swell test. In Colorado, USA, swell potential is classified as low, medium, high or very high based solely on the percent swell. However, the risk of foundation or slab movement relates to the amount of heave that will occur, and heave is more closely associated with the product of the percent swell times the swelling pressure, not just the percent swell. Therefore, a variable termed the “Expansion Potential”, EP, is defined in this paper to express the actual expansion potential of a soil. Values of EP were computed using a database collected from results of more than 1,100 consolidation-swell tests. It is shown that a very good correlation is observed between predicted heave and EP. It is believed that the use of EP will provide a more accurate description of the actual risk of the potential for slab or foundation movement. No correlation was found between the expansion potential and other parameters such as plasticity, dry density, or natural water content