Gholam Moradi - Assistant professor, Tabriz University, Faculty of Civil Engineering
Shiva Seyedi - Ph.D Candidate, Tabriz University, Faculty of Civil Engineering

Colloidal silica is an aqueous suspension of nanoparticles of SiO2. In dilute solutions, colloidal silica has a density and viscosity similar to water. Because of long controllable gel time and low viscosity, colloidal silica can flow into the liquefiable formations slowly over a long time, so it is a potential stabilizer forpassive site remediation. The gel time of colloidal silica depends on several variables. In this study Ludox®-SM colloidal silica was used for testing program. A series of gel time testing were done on samples of dilute solutions of colloidal silica at concentrations 5, 7.5, 10, 12.5, 15 and 30% with differentpH and ionic strengths. The Sydansk gel time description was used to develop gel time curves. On theother hand, the samples of solutions were tested by adding Firoozkooh sand and silt. The results show that gel time decreases as the concentration of silica and ionic strength is increased, minimum gel time occurs between pH 5 and 6 and adding sand and silt decreases solutions gel time, especially out of this pH range

Colloidal Silica, Gel Time, Stabilizer, Liquefiable Solis