A comparative study on soil stabilisation with calcium and magnesium-based binders.
Abstract
Abstract: Soil stabilisation using cementitious materials is a promising technique for improving the mechanical characteristics and suppressing the swelling of expansive and sulfate soil. This study compares the viability of two calcium-based stabilisers (Portland cement-C and lime-L) and one MgO-based stabiliser (magnesium oxide-M) in soil stabilisation. A set of specimens produced by use of two soil materials (pure kaolin soil and artificially gypsum-dosed kaolin) at a constant stabiliser content of 10 wt%, were examined in terms of the unconfined compressive strength (UCS), swelling and derivative thermogravimetric (DTG) analysis. Accordingly, the results revealed that Portland cement (10%C) experienced a superior UCS of 1830 and expansion of 0.44% in the absence of sulfate, whereas magnesium oxide (10%M) outperformed both Portland cement and lime in the suppression of swelling of the artificial sulfate soil, where it induced an expansion magnitude of 1%, relative to that of 15% and 24% for 10%C and 10%L, respectively. However, the 10%M yielded a lower UCS (927 ) relative to that of 2030 for 10%C and 1995 for 10%L in the presence of sulfate. The superiority of 10%C in the absence of sulfate is due to its higher and ions, which provide the needed oxides for the nucleation of the hydrates that interlock the system. As for the dominance of 10%M in the suppression of expansion of sulfate kaolin, it can be assigned to the restriction of the nucleation and growth of ettringite crystals owing to the unavailability of calcium ions.