Chemical stabilization of soil materials using sodium silicate

GRAVEL from Mjimwema and silty CLAY from pugu were selected from four samples, for laboratory for assessing usefulness of Sodium silicate stabilization. Laboratory tests included the determination of compaction characteristics; Atterberg limits, linear shrinkage CBR strength and CBR swell. Stabilization of soil samples involved treatment of 1.04% and 1.73% sodium silicate by weight for soil sample from Mjimwema and 1.30% and 2.16% sodium silicate by weight for soil sample from Pugu. Four and seven days curing were both used followed by four days soaking. On addition of 1.04% sodium silicate by weight, this soil met the requirements for use as improved subgrade materials. Despite the various improvements on soil properties of Silty CLAY from Pugu on addition of sodium silicate, swelling characteristics and linear shrinkage did not improve significantly. Changes in soil properties were more prominent when the soils were allowed to cure for seven days as compared to four days. Sodium silicate is more effective in stabilizing gravelly soil rather than clay. Sodium silicate is also expected to more effective in stabilizing soils with high concentration of divalent metal actions. Further tests are recommended for other major soil types existing in Tanzania, and economical comparison with existing alternatives should be studied.