Microstructural and mechanical properties of marine soft clay stabilized by lime-activated ground granulated blastfurnace slag

• Hydration products of lime-GGBS and PC are similar.
• Lime-GGBS yields lower porosity of stabilized clay than PC.
• Lime-GGBS yields higher strength of stabilized clay than PC.
• Optimum lime/GGBS ratio ranges 0.1–0.2.

Although Portland cement (PC) is widely used for marine soft clay stabilization, there are significant environmental impacts associated with its production. Hence, the use of industrial by-products has been encouraged. In this paper, quicklime and hydrated lime were used to activate ground granulated blastfurnace slag (GGBS), a by-product of the steel industry, for stabilization of marine soft clay in comparison to PC. X-ray diffraction (XRD), scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP), and unconfined compressive strength (UCS),were used to investigate the microstructural and mechanical properties of stabilized clays. The microstructural analysis results revealed that the main hydration products in the two types of lime-GGBS stabilized clays were calcium silicate hydrates (CSH), calcium aluminates (CAH), calcium aluminum silicate hydrates (CASH), and alumino-ferrite monosulfate (AFm), and both types of lime-activated GGBS stabilized clays could yield lower porosity than PC stabilized clay. The UCS results demonstrated that hydrated lime-activated GGBS achieved slightly higher 90-day UCS in stabilized clay than quicklime-activated GGBS, and the optimum 90-day UCS, with a lime/GGBS ratio of 0.10, was 1.7 times that of PC stabilized clay. This study indicated that both environmental and economical benefits could be expected from replacing PC with lime-GGBS for soft clay stabilization.