Case Histories on The Applications of Colloidal Silica for Permeation Grouting-PPT Presentation

PPT Presentation

Pdf Summary

The presentation reviews colloidal silica as a permeation grout for ground stabilization and water control. Grout selection depends on properties such as viscosity, setting time, stability, particle size, strength, durability, and toxicity. Because colloidal silica has very low viscosity and nanoscale particles, it can penetrate fine sands, silty soils, and narrow cracks where cement grouts may be ineffective.<br /><br />Compared with sodium silicate (“water glass”), colloidal silica has a lower pH, water-like viscosity, controllable gel time, and better long-term durability. In saturated conditions it exhibits negligible shrinkage and low leaching. Laboratory studies report improvements in soil strength and cyclic resistance, alongside substantial reductions in permeability.<br /><br />Case histories from multiple countries demonstrate uses including stabilizing running or fine sands, supporting excavations and tunnel faces, sealing groundwater pathways, and controlling settlement. Examples include sewer construction in Monza, cross-passages on Italy’s high-speed rail link, tunnel pre-injection in Portugal, and a sealing barrier on Long Island. At Monza, treatment increased sand cohesion to about 50 kPa and doubled the soil’s elastic modulus. The Long Island project reduced hydraulic conductivity from approximately 10⁻⁴–10⁻⁵ m/s to a mean of 2 × 10⁻⁸ m/s, with sealing performance maintained over six years.<br /><br />Overall, the presentation identifies colloidal silica as a versatile option where low viscosity, penetration into fine soils, controlled gelation, durable strength, and low post-grouting permeability are required.

Keywords

colloidal silica

permeation grout

ground stabilization

water control

low viscosity

fine sands

soil permeability

gel time

tunnel pre-injection

durability