Characteristics of silicon carbide sludge-based geopolymers

Abstract

In this study, metakaolin (MK) with silicon carbide sludge (SiC sludge) was used in the preparation of geopolymers, and its use as a structural material was demonstrated. The production of SiC sludge metakaolin-based (SCM) geopolymers was investigated by using solid/liquid (S/L) ratios of 0.4–1.0 and SiC sludge replacement levels of 0–40% to understand the effects of the geopolymerization process. The results indicated that for SCM geopolymers with SiC sludge replacement levels of 10–40% and a solid–liquid ratio of 1.0, the strength decreased from 70.02 MPa to 48.47 MPa after 56 days of curing. The heat evolution of the first exothermal peak clearly decreased from 990.6 W/g to 835.7 W/g as the SiC sludge content increased from 10 to 40%. After 56 days of curing, the mesopore content decreased from 98.94% to 95.24% in SCM geopolymers with 10% to 40% SiC sludge. After 56 days of curing, SiC sludge replacement levels of 0%, 10% and 40% increased, and the polymerization degree increased to 82.3%, 82.7% and 80.5%, respectively. At a solid–liquid ratio of 1.0, SCM geopolymers with a 10% SiC sludge content exhibited excellent mechanical properties, which accounted for the synergistic effect of the SiC sludge and MK. This study revealed that SCM geopolymers with a SiC sludge replacement level of 10% are beneficial to the geopolymerization process and that they can be used as a structural material.