SILICATIZATION OF STRUCTURALLY UNSTABLE SOILS (Part 1)

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The weak structurally unstable soils, which include loess subsiding soils, can worsen their physical state under the influence of various factors. Silicatization is the general method used by many specialists to provide the stability of constructions on loess territories. However, it was found that in a number of cases the use of single-solution silicatization of loess soils does not decrease the subsidence deformations. A study of the reasons for the insufficient effectiveness of this method has shown the need for activators in the injectable silicate solution that promote the intensification of the interaction process in the “soi–solution” system. For this purpose, various modifications of organosilicate solutions have been used, where amide reagents (formamide and its production waste, such as CWF and dimethylformamide) with high technological properties are used as a curing agents of sodium silicate. A gel of silicic acid (the main cementing material) and ammonia are released as a result of the gelatinization reaction. Ammonia can additionally activate the physicochemical reactions in the system. The studies in laboratory conditions were carried out on loess subsiding soils, that were sampled in various regions of Russia and near abroad countries, differing in their physico-mechanical properties and physicochemical activity (active, transition and inactive types). In this paper it is shown that using organosilicate solutions in comparison with one-component silicatization is the most effective for inactive and transition types of loess soils. High strength characteristics for these soils caused by more complete mobilization of silicic acid and additional formation of organosilicate complexes, which provides their high stability in aggressively acidic environments. The effectiveness of the use of these solutions was confirmed at the experiment-production site of Akademgorodok, Dushanbe (Tajikistan). High strength parameters were obtained when injecting the loess subsiding soils of the foundations of the opera house in Kiev (Ukraine).