Soil–water characteristic curve of lime treated gypseous soil: Fid-Bau Portal

Soil–water characteristic curve of lime treated gypseous soil

Aldaood, Abdulrahman / Bouasker, Marwen / Al-Mukhtar, Muzahim

Abstract The determination of water holding capacity variations with environmental conditions, in particular relative humidity (suction), is essential in the assessment of the behaviour of gypseous soil. The relationship between suction and moisture content is expressed by the soil-water retention curve (SWRC) or soil-water characteristic curve (SWCC). This relationship was determined for the first time for lime treated gypseous soil, using tensiometric plate, osmotic membrane and vapour equilibrium techniques, in the suction pressure range of (10–1,000,000 kPa). Soil samples containing (0, 5, 15 and 25%) gypsum were treated with 3% lime and cured for 28, 90 and 180days at 20°C and 40°C. Results showed that the water holding capacity of the soil samples increased with increasing gypsum content, curing period and curing temperature. The effect of gypsum content on SWCC was greater than the effect of curing conditions, although microstructural properties of the treated soil samples showed that curing conditions also had a significant effect on the SWCC. All the experimental data fitted well to the Fredlund and Xing (1994) and Van Genuchten (1980) models for SWCC.

Highlights • This study is the first to address the SWCC of lime treated gypseous soils. • Volumetric water content at air entry increases with gypsum content. • Curing temperature increases the water holding capacity in the low suction range. • Experimental SWCC were modeled by both Fredlund and Van Genuchten's equations.