2.1.1 Soil
The used soil in this study was obtained from a site, namely Barika
soil, situated in Sulaimani governorate, northern Iraq. The studied
natural soil is collected at a depth of 0.5 to 1 m from the natural
ground level, and is normally consolidated clay. The undisturbed and
disturbed soil sample were excavated, placed in plastic bags, and
transported to the geotechnical laboratory for testing. Geotechnical
laboratory tests were performed on the soil to determine its
geotechnical properties. The obtained clayey soil sample was light brown
in color, and is composed of some clay. It can be defined as low
plasticity soil according to the Unified Soil Classification System
(Akbulut, 1999; Kalkan, 2003; Kalkan and Bayraktutan, 2008, Rashed et
al., 2017). Extreme precautions were taken during soil sampling to keep
the collected soil samples in their natural moisture content and field
density conditions. The particle size distribution curve of Barika
clayey soil is shown in Figure 1. The tested sample can be classified,
according to ASTM Standard (D422, 1990), as CL soil. The obtained
properties of the untreated soil sample are summarized in Table 1. The
selected lime for the study is hydrated lime, Ca
(OH)2, white color in the form of fine powder.
Table 1: Geotechnical properties of the tested untreated Barika
CL soil sample.