Damage due to soil swelling is very noticeable in wide spectrum of structures such asrnroads, buildings, canal linings, landfill liners, etc. To evaluate severity of swelling and torndesign for the best and most economical stabilization strategy, an accurate assessment ofrnthe swell potential is required.rnThe main reason of swelling behavior is water absorption of soil mass in time. And therntime required for completion of swelling is relatively long. In view of that severalrnattempts have been made by researchers to obtain time-swell relationships for expansivernsoils. Some progress has been made toward characterizing swelling characteristics,rndespite the complexity of the behavior.rnIn this study a simple hyperbolic mathematical model is used to predict the swellingrnbehavior of an expansive soil from Addis Ababa. The formula was first proposed byrnRichard and Abbot, 1975.rnThe model was formed in one equation with many parameters. The main advantage ofrnthis model is that only one parameter is needed to run the model. The main parametersrnthat are needed to run the model are the applied pressure and initial dry density. The otherrnparameters of the model including the initial slope of the swell-time curve, the finalrnslope, the reference swell, and the peak swell were investigated experimentally.rnBased on the experimental results, empirical relationships were developed forrndetermination of these parameters as functions of the applied pressure and initial dryrndensity. The model prediction were compared with the experimental results and showedrngood agreements for all levels of applied pressure and initial dry density of the tested soil.