Class C flyash, baghouse dust and scrubber sludge have been successfully used for
sulphoaluminate belite (SAB)
cement preparation by microwave sintering. For proper raw mix proportioning, the modulus of gehlenite (C
2AS)
1 formation (MG) and modulus of calcium sulphosilicate (2C
2S·C
S) formation (MS) were put forward. The results indicated that, when MG and MS were 0.90–1.10, C
2AS and 2C
2S·C
S could be chemically eliminated when microwave-sintered at low temperature; with the 1150°C/10 min sintering condition, microwave-prepared sample had developed into SAB
cement clinker with the main phases of C
4A
3S and β-C
2S, while a conventionally fired one had not; with proper gypsum addition, microwave-prepared SAB
cement developed strength similar to Type-I
cement in 28-day hydration.