Influence of drying-wetting cycles on engineering properties of carbonated silt admixed with reactive MgO

The engineering properties of reactive MgO-carbonated silt have been extensively investigated in previous studies. However, very few studies have comprehensively addressed the effects of drying-wetting cycles on the engineering properties of MgO-carbonated silt. This paper investigates the apparent property, mass change ratio (viz., the ratio of the mass loss after the drying-wetting cycles to the original mass), water content, dry density, pH, confined compressive strength and elasticity modulus as well as microstructural characteristics of reactive MgO-carbonated silt after several drying-wetting cycles. The ordinary Portland cement (PC)-stabilized silt is used as a control sample for comparison. The results indicate that the maximum mass change ratio, water content and soil pH of MgO-carbonated silt are much lower than the corresponding values of PC-stabilized silt. The dry density of MgO-carbonated silt (>1.7 g/cm(3)) which is larger than that of PC-stabilized silt (similar to 1.57 g/cm(3)) decreases with increasing the number of drying-wetting cycles. Both unconfined compressive strength and elasticity modulus of MgO-carbonated silt are almost twice those of PC-stabilized silt in spite of drying-wetting cycles. With increasing the number of drying-wetting cycles, the elongated-rodlike nesquehonite gradually transforms into the loose rosette-flaky dypingite/hydromagnesite, and the volumes of total pore and intra-aggregate pore as well as small pore increase obviously while the medium pore volume reduces to varying degrees. (C) 2019 Elsevier Ltd. All rights reserved.