The Bentonite of Maghnia in the north-west of Algeria was used in this study. The soil was subject to several laboratory tests using standard procedures in accordance with AFNOR and ISO standards 38, 39, 40, 41, 42.
Fig. 1 presents the grain size distribution curve of the soil. The soil has specific gravity Gs = 2.77, liquid limit = 135% and plasticity index = 88%; the soil is classified as high-plasticity clay (CH) according to the Unified Soil Classification System (USCS). Physical and engineering properties of bentonite are given in Table 1. A chemical composition of bentonite was carried out in accordance with NF EN 1744 43, and the results are presented in Table 2.