Optimization of Cement-Silica fume blends for the suppression of sulphate soil swelling

الملخص

The expansion resulting from the ettringite nucleation in sulfate soil treated with calcium-based stabilisers causes a technical and economic issue for geotechnical engineering. Thus, this research investigates the practicability of co-utilization of cement (C) and silica fume (S) at a variety of blending ratios (10, 30, 50 and 70 wt%), with a view of determining the optimum blinder of C–S for restricting the development of ettringite minerals in soil samples rich in sulfate (9% gypsum). To achieve this target, a series of laboratory samples, prepared at different cement and silica fume concentrations, were examined using unconfined compression strength (UCS), linear expansion, and derivative thermo-gravimetric analysis (DTG) as the key criteria for the evaluation. The research observations revealed a gradual reduction in strength and expansion, as the substitution ratio of cement with silica fume increased to 30% and 70%, respectively. Therefore, 7C–3S was categorised as the optimal blending ratio for UCS, while 7C–3S was superior in terms of the expansion, as it exhibited a lower expansion magnitude of 1.42%. Accordingly, the use of silica fume has proven to be an effective approach for restricting the nucleation of ettringite minerals in cemented sulfate-bearing soil.