Effect of Colloidal Silica Aqueous Gel on the Monotonic and Cyclic Response of Sands

The response of sands stabilized with colloidal silica aqueous gel is investigated in the laboratory. The role of colloidal silica on subsequent sand behavior is examined with the aid of monotonic and cyclic loading tests so as to establish the mechanical response of the treated sand. Depending on the loading conditions when the strength of the treated sand is enhanced and liquefaction is averted, its stiffness may reduce and its compressibility increase. This contradictory behavior is investigated on the basis of an extended database including direct shear, triaxial, and normal compression tests. Initial stiffness is lower for treated sand compared with untreated sand under drained and undrained monotonic loading conditions. It is demonstrated that only dense treated sand shows similar stress-strain properties with the untreated sand under cyclic loading, whereas loose treated sand accumulates strain and excess pore-water pressure much faster than the untreated sand. The critical state line applying to the treated sand lies substantially above that manifested by untreated sand. The two lines converge as the stress level increases to around 2,000 kPa.