Experimental Evidence of the Effectiveness and Applicability of Colloidal Nanosilica Grouting for Liquefaction Mitigation

The low viscosity and the ability to control solidification rate make colloidal nanosilica grout an excellent ground-improvement solution which is functional for different engineering purposes. A comprehensive experimental programme was performed to test the effectiveness and applicability of low-pressure injection of aqueous nanosilica suspensions against seismic liquefaction and to provide the experimental basis for the design, execution, and control of treatments. Scanning electron microscope and X-ray diffraction tests carried out on samples prepared with variable dosages enabled analysis of the microstructure of the original material and grouted sand. The influence of the grout composition on the solidification rate, viscosity, and shear strength of the treated sand was evaluated with preliminary tests to optimize the use of material. The efficacy of treatment in terms of stress-strain response and liquefaction resistance was investigated with a series of drained monotonic and undrained cyclic triaxial tests. A quality control procedure based on sonic wave transmission was established by performing bender element tests on samples cured for different times. The intent was to find the trade-off between a cost-effective use of materials and the mechanical performance of the treated sand.