Multiscale Study of Sodium Sulfate Soaking Durability of Low Plastic Clay Stabilized by Reactive Magnesia-Activated Ground Granulated Blast-Furnace Slag

Portland cement (PC) has been used extensively in ground improvement. However, environmental effects caused by PC production and durability of PC-stabilized soils when exposed to sulfate attack are of global concern. Previous studies show that reactive magnesia-activated ground granulated blast-furnace slag (GGBS) is a viable sustainable alternative binder to PC. However, limited research has been conducted on the durability of GGBS-magnesia (MgO) stabilized soft soils subjected to sulfate attack. This study presents a multiscale investigation on the performance of the reactive MgO-activated GGBS stabilized kaolin clay when soaked in a concentrated sulfate sodium solution. PC is adopted as a control binder for the purpose of comparison. The macroscale variations in mass change (MC), water content (w), dry density (ρd), soil pH, and unconfined compressive strength (qu) of GGBS-MgO and PC-stabilized kaolin clay under a sulfate sodium solution soaking condition are investigated. The results demonstrate that sodium sulfate attack has much less significant affect on the surface integrity, mass loss, ρd, and qu of the GGBS-MgO stabilized soil as compared with the PC-stabilized kaolin clay. These results are assessed on the basis of the microscale analyses of major hydration products, microstructure, and pore size distributions of the stabilized soils, which are obtained from X-ray diffraction (XRD), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP) tests, respectively.