An inexpensive experimental system for measuring suction profiles during transient moisture movement processes in unsaturated expansive clays was developed. The system relies on measurements of total suction using the noncontact filter paper technique at several stations along a one-dimensional soil column. Performance of the system was demonstrated for a column of compacted Ca2+-smectite undergoing evaporation at the top boundary under ambient laboratory conditions for 91 days. The system was most applicable during latter stages of drying when the rate of moisture movement was slow enough to be adequately captured by the required 7-day measurement interval and the suction values are large enough to offset scatter. Final water content and suction profiles were determined gravimetrically and compared with values obtained from the filter paper measurements. Desiccation cracking did not significantly affect the accuracy of the filter paper system. The research forms an experimental basis to develop or verify theoretical models aimed at predicting moisture flux for in situ expansive soil subject to infiltration or evaporation processes.
Abstract