The aim of this research was to investigate the permeability of sodium silicate grouted sand specimens having various gradations and relative densities. Initially, rheological properties of sodium silicate grouts were studied. The gel time decreased as the sodium silicate content increased. Viscosities of sodium silicate grouts increased as the silicate content increased. Syneresis of sodium silicate grout gels increased with the increase of silicate content up to a point and then started decreasing sharply. The penetrability of chemical grouts with different sodium silicate contents into various graded sand specimens prepared at different relative densities was highly successful. Grouted sand samples were kept in humid conditions at a temperature of 20 degrees C until testing time and were subjected to permeability tests at different time intervals. In general, sodium silicate grouting reduced the permeability of various graded sand specimens. The permeability of grouted sand specimens slightly increased with time as a result of syneresis.