A review of soil improvement with non-conventional grouts

Soil improvement by grouting is one of the methods applicable to solve problems connected to foundations, open cut excavations, and tunnelling. The improvement of soils is in terms of reduced permeability and increased strength. It has traditionally relied on treatment with cement and lime. Chemical grouts are normally used to penetrate finely fissured rocks or fine-sands. To help practising engineers and to promote best practice, this paper presents a critical reappraisal of selected research papers where non-conventional cementitious grouts were employed. Sodium silicate, colloidal silica, resins, polymers, and microfine cement as grouting materials in sand and cohesive soils were critically reviewed. The aim of this paper is to provide useful information for contractors and consultants when designing injection works utilizing non-cementitious fluids in the future.Abbreviations: Colloidal silica: CS; CSR: Cyclic stress ratio; ER: epoxy resin; SS: sodium silicate; UCS: unconfined compressive strength; N: groutability of a cementitious grout; D15: diameter of the particle smaller than 15%; D85: diameter of the particle smaller than 85%; D95: diameter of particle smaller than 95%; Dr: relative density; k: coefficient of permeability; σd: deviatoric stress (σ1–σ3); σv0′: vertical effective stress; τcyc: cyclic shear stress