Stabilization of Geomaterials using an Innovative Form of Sodium Silicate

Yu Guo, Julie Qiulin Shang, Bingfeng Xue, Michael McDonald, Xianglian Li, Timothy Evans

In the proceedings of: GeoOttawa 2017: 70th Canadian Geotechnical Conference; 12th joint with IAH-CNC

Session: Soil Amendments

ABSTRACT: Sodium silicate has been a major class of chemical grouts for several decades. A wide variety of silicate-based formulations have been developed to address various requirements for water control and/or soil stabilization. However, formulations have relied on a narrow range of commercially - available sodium silicates. Recently, a new form of sodium silicate has been developed that has much lower alkalinity with a higher ratio of silica compared to conventional silicates. To study the suitability of this new silicate for chemical grouting of geomaterials, including loose sand and fine oil sand tailings, an in-depth experimental study was conducted to investigate the effects of chemical grouts in terms of strength gain, durability, gelation time and selection of setting agents. The study compared conventional sodium silicate with the new, higher - ratio silicate. The experimental work first modeled viscosity and set times using two different setting agents, i.e. triacetin and citric acid. The results of this study indicate that the chemistry of the high ratio silicate has several features that would be enhancements over existing silicate technology. First, the reduced alkalinity further improves the environmental performance of sodium silicate by reducing the amount of leachable sodium. Operationally, the higher ratio silicate can be formulated to have much longer set times. Further, set times were easier to control and could be achieved using significantly less setting agent. Upon setting, the gelled silica had greater dimensional stability. Testing of unconfined compressive strength and durability is on-going but initial results indicate significantly better performance compared to conventional silicates. Initial field trials have been confined to water control applications and have demonstrated good efficacy as well as the noted improvement in ease of use. Résumé Le silicate de sodium a été une classe importante de coulis chimique depuis plusieurs années. Une grande variété de et/ou de stabilisation des sols. Cependant, ces formulations comptent sur une gamme étroite de silicates de sodium disponibles commercialement. Récemment, une nouvelle forme de silicate de sodium a été développée avec une alcalinité beaucoup plus faible et un niveau plus élevé de silice par rapport aux silicates conventionnels. Pour étudier la pertinence de ce nouveau silicate pour le jointoiement chimique des géomatériaux , y compris le sable et résidus fins de sables bitumineux, une étude expérimentale approfondie a été menét porté sur la Les résultats de cette étude indiquent que la chimie du silicate au haut contenu de silice présente plusieurs améliorations compare au silicate convenvironnementale en réduisant la quantité de sodium lixiviable. Sur le plan opérationnel, le silicate à haut taux de silice peut être formule pour avoir des temps de fixation plus longs. De plus, les temps de fixation sont plus faciles à contrôler résistance à la compression est en cours et les résultats initiaux indique une performance similaire ou supérieure au ion.

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