The silica soda ratios of sodium silicate: Its foundry importance

The paper describes the role of silica to soda ratio of sodium silicate in controlling the development of compression strength of sand aggregates with different hardeners. The results show that the compression strength increases with increase in silica to soda ratio up to a limit for all hardening systems investigated. The authors recommend specification of sodium silicate bonded sands to include the ratio silica to soda along with percentages of binder and hardener, since a lower ratio silicate may require higher setting time than a higher ratio silicate to attain the same strength. (Shri S. Ghosh, Scientist, Shri R.R. Dash, Senior Scientific Assistant, Shri G.N. Rao, Scientist, National Metallurgical Laboratory)