Co-disposal of semi-dry desulfurization residue and red mud into high performance alkali activated material

• Efficient method was developed to convert DR and RM into precursors for AAM synthesis. • The synthesized AAMs achieved excellent mechanical properties. • Main reaction products are gypsum, hydrotalcite and C-A S H gel. Disposal of flue gas desulphurization residue (DR) and red mud (RM) has been a focused problem due to the huge amounts and complicated compositions. In this work, an efficient co-disposal method was developed, through which DR and RM can be converted into solid precursors for the synthesis of high strength alkali activated materials (AAM). The effect of DR/RM mass ratio and calcination temperature on mineralogical composition of obtained precursors were investigated, together with the mechanical properties, microstructure, chemistry of reaction products of the synthesized AAM. Results show that the synthesized AAMs achieved excellent mechanical properties, with 3 d and 28 d compressive strength of 7.7–25.1 MPa and 30.1–58.8 MPa, respectively. Main reaction products include gypsum, hydrotalcite and C-A S H gel.