Design of Permeation Grouting Treatments with Eco-Friendly Nanosilica Grouts

Nanosilica aqueous suspensions are mechanically flexible and environmentally non-toxic materials. These are injected into soils at low pressures as fast remedials to stop piping induced by excavations, for the sealing of contaminants or to reduce the seismic-induced liquefaction potential. To adopt the technique, it is crucial to firstly predict the temporal evolution of the permeation process highly affected not only by operational parameters, but also by the time-dependent rheological properties of the employed grout. In this paper, a simplified method to design permeation grouting treatments with eco-friendly nanosilica grouts is proposed. Its employment is discussed focusing on how to rationally optimize the injection process in terms of nozzle spacing, injection time, grout compositions and pump pressure. This can be a useful tool in practical applications also to interpret the experimental results obtained from trial in situ tests, always recommended before grouting. The final goal is to guarantee a more efficient design approach for these treatments, currently absent in the scientific literature, taking not only times and costs but also environmental impact into account.