Effect of Dry and Saturated Bentonite on Plastic Concrete

Abstract

Dams are rarely built on non-permeable lands, therefore usually reservoir leakage from dam foundations cause major problems for large dams which affect dams performances. One method of controlling the origin of leaks is to use plastic concrete cutoff walls. Bentonite is one of the most important materials used in constructing plastic concrete which act as a stabilizing agent. It is from clay materials having high water absorption and swelling of 300% properties even after contacting with water. These properties may cause negative effects on plastic concretes that include deep cracks and high reductions on its strength. In order to eliminate these effects, plastic concretes must be mixed with water at least 24 hours before usage and then they must be blended by special blades until they are totally saturated. This process costs huge time and money. Therefore, in this research, dry bentonite has been added to the mixer with particular method. It can be seen saving time and money and the properties of plastic concrete such as compressive strength, tensile strength, slump and permeability will not be slightly changed.