Synthesis of Alkali-Activated Binary Blended Silico-Manganese Fume and Ground Blast Furnace Slag Mortar

Abstract

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 Na 2 SiO 3 of an initial silica modulus of 3.3. The Na 2 SiO 3 /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-AS -H), gehlenite hydrate (C-AS -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.

Sulfuric acid resistance of alkali/slag activated silico‐manganese fume‐based mortars

“…The less reactivity of SB(0)M(10)E(W) system also led to deep bending and stretching vibration bands of interlayer water molecules (OH and H‐O‐H) at 1640/3330 cm −1. 20 This suggests that proliferation of hydroxyl ions have the propensity to react with atmospheric carbon to form carbonate ion (CO 3 2− ), as is evident from the emergence of ν3 stretching vibration mode of carbonate band (O=C=O) at 1400 cm −1 . Conversely, SB(0.3)M(10)E(W) system exhibited almost symmetric stretching of Si‐O‐T and its position shifted to lower wavenumber (965 cm −1 ).…”

“…The mass ratio of Na 2 SiO 3 to NaOH = 2.5, sand to SMs = 1.8 and AAs to SMs = 0.5 were kept invariant. The paste and mortar mixtures were identical except the sand was excluded in the former type, as practiced by Aiken et al 16 The mixtures were designated as SB(x)M(y)E(z) where “SB” represents SMF (S) and BFS (B) as starting material (SMs), “x” represents the ratio of B to total SMs that is, B/(B + S) = 0 or 0.3, 20 “y” represents molarity (M) of NaOH aq = 4 or 10 and “z” represents exposure (E) to either pure water (W) or sulfuric acid (SA). For example, SB(0)M(10)E(W) indicates that the mix constitutes: (a) B/(B + S) = 0, that is, 0% BFS and 100% SMF; (b) 10 M NaOH aq solution and (c) exposed to pure water.…”

“…SMF is recently identified and proposed as a potential precursor for the development of AABs by Najamuddin et al 18 and Nasir et al 19 Najamuddin et al 18 suggested a high alkaline concentration of NaOH and activator dosage (NaOH/Na 2 SiO 3 ) of 10 M and 2.5, respectively, for better mechanical properties. Due to dearth of Ca and abundance in Mn and K ions in SMF compared to SMS, a blend of 70% SMF and 30% blast furnace slag (BFS) has been reported to produce a binder of significant compressive strength 19,20 …”

Sodium sulfate resistance of alkali/slag activated silico–manganese fume‐based composites

“…The specimens were termed as R(a)M(b)E(c) where “a” represents ratio of BFS to total PMs [BFS/(BFS + SMF) = 0 or 0.3], 32,33 “b” represents molarity (M) of NaOH aq = 4 or 10, and “c” represents exposure (E) state as either only water (W) or with 5% sodium sulfate (SS). For instance, R(0.3)M(10)E(W) indicates: (a) BFS/PMs ratio = 0.3 that is, 30% BFS and 70% SMF; (b) 10 M NH aq ; and (c) exposed to pure water.…”

“…He asserted that slag is an ennoble contributor against sulfate resistance providing microstructural stability, whereas the activator ratio did not play any significant role. The authors 32,33 recently established that excessive CO 3 2− and weak ─OH compounds of alkali‐activated silico–manganese fume (SMF) mortar can be beneficially minimized with the inclusion of 30% slag owing to its capabilities of pore plugging, crack bridging, and densification of the microstructure.…”