This study addresses the use of an industry by-product, carbide slag (CS), to activate another industry by-product, ground granulated blastfurnace slag (GGBS), for soft clay stabilization in comparison to Portland cement (PC). The properties of CSGGBS stabilized clays were investigated through unconfined compressive strength (UCS) test, mercury intrusion porosimetry (MIP), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The results indicated that the optimum CS content for the CSGGBS stabilized clay to yield the highest UCS was 4%6%, varying slightly with curing age and GGBS content. The UCS of the optimum CS-GGBS stabilized clays was more than twice that of the corresponding PC stabilized clays. The main hydration products detected for the CSGGBS stabilized clays included calcium silicate hydrates (CSH), calcium aluminate hydrates (CAH), and alumino-ferrite monosulfate (AFm).