Investigation on the Bentonite samples received from Indian Standards Institution

The indigenous bentonite samples were designated RNA, Select-Grill, K-1,K-2-N, bentoclay and CH. Moisture contents of all the samples were in agreement with the (tentative) specifications for “ Western bentonite” of steel Founder’s Society of America. Chemical analyses showed that Fe2O3 was high in all the samples. About 7-9% obtained in all the samples. TiO2 was also found to be very high in all the samples except the RNA bentonite. High amounts of Ca base. Samples designated RNA, K-2-N and bentoclay had comparatively high swelling characteristics and these had 27, 37, and 42 percent respectively as their gel strength values which showed their approximate montmorillonite- contents according to the Silica Products Co. The other three samples namely Select-grill, K-1 and CH evidently had low swelling characteristics and their approximate montmorillonite contents were only 16, 17 and 23 percent respectively. More than 60 percent of all the samples except K-1 and K-2-N passed through a 325 mesh sieve of the U.S. sieve series. In other words 60 percent of all the samples except K-1 and K-2-N, had particle size of less than 0.0017 microns which showed their very fine particles size. Results are drawn from the dry fineness results. pH-values of all the bentonite were in agreement with the same specification of SFSA referred to previously.