Bentonite suspension is used as stabilizing fluid to support pile borings, excavation trenches and for cement grouting in many geotechnical applications. Bentonite suspension can also be used with cementitious material as a binder to create self-hardening mixtures such as grouting mortars for construction of cut-off walls. Effective usage of bentonite suspension and grout is strongly influenced by the fluid properties such as thixotropy and viscosity. These are dependent on various factors such as the proportion of bentonite to water, its hydration time, temperature, bleed, mixing methodology, additives etc. When bentonite suspension is being prepared, the objective is to achieve maximum hydration of the bentonite with suitable gel formation which can be achieved by effective mixing. Greater agitation, longer mixing and more hydration results in good quality bentonite suspension. This paper discusses the effects of mixing for various proportions of bentonite to water and bentonite to cement suspensions. From the results of laboratory and field tests conducted in large infrastructure projects, it is understood that with the % of bentonite usage and addition of admixture, properties such as viscosity and bleed can be reduced in the cement- bentonite suspensions. This in turn is primarily dependent on the use of high shear mixing and proper hydration of bentonite.
Subjects: bentonite, mixing methodology, viscosity, density, hydration time, bentonite-cement grout
Author: Akhila Manne and Madan Kumar Annam