Influence of Bentonite Content on the Compressibility Parameters of Processed Sand-Bentonite Mixtures

Abstract

Bentonite has employed by industry to exercise various structural applications due to its unique properties especially when the material is transferred to a liquid state under water. Swelling property of bentonite to produce various water suspensions, which depends upon the relative constituents of clay and water. These mixtures are employed as bonding and plasticizing agents. Bentonite provides a large surface areas per unit weight of clay, due to its large surface area in stabilizing the medium to carry other chemicals. Bentonite react chemically with many organic material to form compounds which are used as a gelling agents in a variety of organic liquids.One-dimensional consolidation tests are performed on four sand-bentonite mixtures containing 10, 20, 30 and 40 % by dry weight bentonite to study the 1-D compressibility behavior of compacted sand-bentonite mixtures. These speciments are mixed at wet of optimum water content. To overcome the problem of the high tendency of bentonite to swell, two techniques are used. The first one is following the consolidation-swel test procedure by Nelson and Millerand the other one is mixing the soil at water content equivalent to liquid limit. The water contents for these tests are chosen in an attempt to achieve the same initial void ratio of 0.71 for all bentonite contents. Finally, final conclusion is mentioned for the effect of bentonit content on the compressibility parameters of sand-bentonite mixtures. This research arrived to that the initial water content has no effect on the mixture,which contains10 percent bentonite, whereas a significant effect is noticed for 20 and 30 % bentonite mixtures. It was found that for mixtures containing 20 and 30 % bentonite, the compressibility parameters, Cc, Cs, av, and m_v for the specimens mixed at liquid limit are higher than those for specimens mixed wet of w_opt.