Synthesis of alkali-activated binary blended silico-manganese fume and ground blast furnace slag mortar

This study was aimed at developing novel and sustainable alkali-activated binder of silico-manganese fume (SMF) and ground blast furnace slag (BFS) at room temperature. The level of BFS substitution was varied from 0 - 50% and activation was done using 10 M NaOH and Na2SiO3 of an initial silica modulus of 3.3. The Na2SiO3/10MNaOH ratio was kept constant at 2.5. The setting time, flow and compressive strength were evaluated and complemented with the microstructural and bond characteristics of the product. A 28-day strength of 45 MPa was achieved with the base materials ratio (BFS/(BFS+SMF)) of 0.3. The activation of SMF resulted in the formation of glaucochroite and nchwaningite minerals (C-Mn-S-H) while the inclusion of BFS influenced the formation of potassium feldspar (K-A-S-H), gehlenite hydrate (C-A-S-H) and additional C-S-H due to later-age contribution of hydration of BFS. The Manganese in SMF contributed significantly to the consistency of the mixture while lime in BFS improved the microstructure thereby enhancing strength of the developed alkali-activated binder.