Permeation grouting of silt-sand mixtures

• Criteria for permeation grouting are set in terms of the soil water permeability value. • A sand-silt soil was injected with different permeability values. • Five binders were injected. • Compressive strength and creep tests were performed. In permeation grouting, a fluid carrying a binder enters the soil voids under low pressure. The binder sets and cures in the ground, thereby creating a treated soil with larger strength and stiffness and reduced permeability. Permeation grouting is one of the oldest technologies in ground improvement, but also one with a fast pace of technological improvement due to the apparition of new binders. Permeation grouting is frequently associated with cohesionless soils (e.g. gravel and sand), but the boundary of applicability of the technique has gradually shifted towards finer materials. Applicability criteria for permeation grouting are frequently set in terms of the host soil water permeability value, k w , but published empirical basis for available criteria is relatively scarce. In this study, we mixed sand and silt to create soils covering three orders of magnitude of k w and permeated them, in a controlled environment, using five binders of current use: two cement-based, two colloidal silica and an acrylic resin. X-ray tomography, unconfined compressive strength and creep tests are employed to evaluate grout penetration and grouted soil performance. This study is of valuable interest for designers and contractors dealing with grouting technologies.