An Evaluation of Several Methods of Estimating Soil Volume Change

The accuracy of several previously proposed methods of estimating potential soil volume change was evaluated using samples from the B2 horizons of three pedons of each of five soil series having various swelling characteristics. Models involving swell index, plasticity index, clay content, activity index, initial and final water contents, shrinkage limit, shrinkage ratio, liquid limit, linear shrinkage, and hygroscopic moisture content were evaluated by regression analysis with percent volume change of natural clods as the dependent variable. Most methods were found to be either too imprecise or too involved to be useful. The most practical correlations were with swell index ( r 2 = 0.92) and with plasticity index ( r 2 = 0.79). Estimates using these procedures should be used cautiously since their accuracy is only ± 12 to 18% volume change, respectively, at the 95% confidence level.