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There are considerable resource reuse and environmental concerns regarding SiC sludge (SiCS) that results from cutting silicon ingots into wafers. In the current study, the effect of the Na2SiO3 solution/sodium hydroxide solution (NS/SS) mass ratio and SiCS amount on metakaolin geopolymers was found during geopolymerization system performance. The results indicate that while NS/SS ratio was relatively low, increasing the NaOH content resulted in a sufficient amount of OH− in the system to increase the solubility and hinder polycondensation, as indicated by the bulk density and setting-time results; since the polycondensation was inhibited, the mechanical strength was reduced. This study demonstrated that a geopolymer can be formed from a substitution of 10% SiCS and with an NS/SS ratio of 1.6, and that this geopolymer is a feasible material.

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This study investigated a geopolymerization system focused on the effects of the solid-to-liquid ratio (S/L) were ranging from 0.4 to 1.0, which produces geopolymers with various silicon carbide sludge (SCS) replacement levels (0-40 wt. %). The results indicated that the silicon carbide sludge metakaolin-based (SCSMB) geopolymers increased S/L ratios from 0.8 to 1.0, reducing initial and final setting times. Flexural strength of SCSMB geopolymers of the SL ratio of 0.4 increased rapidly from 1.31 to 1.70 MPa during the early stage of curing (1-14 days). For SCSMB geopolymers with 10-40% SCS replacement, peak of Si O Si bonds for geopolymers at 524 cm −1 shifted to a higher wavenumber of 527 cm −1. 29 Si nuclear magnetic resonance (NMR) showed that SCSMB geopolymer with an SCS replacement ratio of 10% increased S/L ratios from 0.8 to 1.0 (56 days) and increased the fractions of Q 4 (3Al; 38.2%-38.4%), Q 4 (2Al; 28.7%-31.7%), and Q 4 (1Al; 13.7%-14.6%). Moreover, the peak in 29 Si NMR spectra shifted to the right side (higher frequency), indicating that an increased number of aluminum tetrahedrons coordinated with silicon tetrahedrons. SCSMB geopolymers with 10% SCS replacement and an S/L ratio of 1.0 yielded highly favorable mechanical characteristics and microstructure.