Soil Properties Influencing Swelling in Canfield and Geeburg Soils1
- D. E. McCormack and
- L. P. Wilding2
Swelling phenomena were measured on Saran3-coated undisturbed clods, trimmed undisturbed samples in a consolidation frame, and on remolded compacted samples in the Percent volume change (PVC) meter and in a consolidation frame. Three horizons of the Canfield series and two horizons of the Geeburg series were studied at each of five sites. Swelling pressures of 1.5 to 2.0 kg/cm2 were measured for the clayey Geeburg samples; in the loamy Canfield samples swelling pressure was generally < 1.0 kg/cm2. Percent swell ranges from 5 to 8% in Geeburg soils and is generally < 1% in Canfield soils. Where other parameters are held constant, most of the variation in swelling is explained by variation in clay content. Values of r2 as high as 0.93 were derived. Coarse clay content is more highly correlated with swelling than fine clay content, possibly because of the effect of the higher charge density of the coarse clay on the thickness of oriented water films. Results indicate that expansive soils continue to swell at moisture contents above ⅓-bar tension, and continue to shrink at moisture contents below 15-bar tension and below the shrinkage limit.
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