Development of a New, Advanced Form of Sodium Silicate for Chemical Grouting-Paper

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The paper presents a cost-effective process for producing high-ratio sodium silicate (4.5 SiO₂:Na₂O), a grout intended to combine advantages of conventional sodium silicate and colloidal silica. Compared with the commonly used 3.2-ratio product, it contains substantially less sodium and has lower viscosity at some concentrations, potentially enabling easier injection and reducing sodium leaching.<br /><br />Researchers at the University of Western Ontario evaluated gelation, durability, permeability, and soil-strengthening performance using sand specimens and environmentally acceptable setting agents, principally citric acid and triacetin. The 4.5-ratio grout formed a more water-resistant gel and reduced sand permeability by about four orders of magnitude. Tests also indicated higher compressive strength than conventional silicate formulations. In wetting-and-drying cycles, triacetin-set specimens lost only 2.3% of their weight after 12 cycles; citric-acid-set specimens performed well until cracking occurred during the sixth cycle. Microscopy showed grout filling soil voids and binding sand grains, with a denser structure than that produced by 3.2-ratio silicate.<br /><br />The higher-ratio material also displayed less syneresis (gel shrinkage), attributed to changes in silicate structure during manufacture. This may improve long-term water-blocking performance and reduce sodium dissolution. Citric acid was highlighted for its favorable environmental profile.<br /><br />Oilfield trials have used the grout both alone and ahead of cement to block water or gas and remediate cement. Initial results were generally technically and economically successful, though treatment sizing and material placement affected outcomes, and long-term performance monitoring continues. Geotechnical applications were still under evaluation.<br /><br />Overall, 4.5-ratio sodium silicate appears to offer improved durability, controllable gelation, reduced sodium content, and strong permeability reduction while retaining the practical benefits of conventional silicate grout.
Keywords
sodium silicate
4.5 ratio
grout
gelation
permeability reduction
soil strengthening
citric acid
triacetin
oilfield trials
durability