Moisture retention and plasticity of highly calcareous soils in Egypt.

Abstract

Particle size distribution, moisture retention curves and consistency limits were determined for six soils from northwestern Egypt. The soils contained 25-61% CaCO3 and attapulgite was the major clay mineral. In the clay and clay loam soils the CaCO3 was predominantly in the silt and clay fractions, in the sandy loam it was regularly distributed over the clay, silt and sand fractions and in the loamy sand it was mainly in the sand fraction. Decalcification shifted the particle size distribution to a coarser texture class and increased porosity and moisture content. Liquid limit and plasticity index increased with increasing clay and CaCO3 contents up to 40% clay and 35% CaCO3. The plastic limit stayed rather constant at increasing clay and CaCO3 contents. The liquid limit corresponded with suctions of pF 1.3-1.9 within the flex range from the saturated to the unsaturated condition of the pF curves. The plastic limit and the plasticity index corresponded with pF 2.1-3.0 and 2.6-3.8, respectively. (Abstract retrieved from CAB Abstracts by CABI’s permission)