Effect of dry ice as admixture on engineering properties of alkali-activated slag: setting time, strength, and sustainability

Alkali-activated slag (AAS) is a low-carbon binder with the potential to replace cement-based materials. In this study, AAS was prepared by using dry ice as an admixture. The effects of dry ice on the actual engineering properties, such as the initial and final setting times and compressive strength of the AAS, were studied. In addition, the microstructure of the AAS was analyzed with X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy. The results of these experiments revealed that the added dry ice increased the setting time of the AAS. The initial and final setting times of the AAS with 2.5 7.5% dry ice were prolonged by 59 122 and 118 173 min, respectively. Furthermore, the addition of dry ice to the AAS improved its mechanical properties. At 28 days, the compressive strengths of the AAS supplemented with dry ice were 4.7 11.6% higher than that of the control group.