(600g) Influence of Dry-Coating of Nano Additives on Particulate Solid Flow and Its Reactions: Cement System a Case Study

The influence of dry coating of nano-additives on flow and decomposition of CaCO₃, reactivity of CaO towards di-calcium silicate (C₂S) phase formation and stabilization of C₂S in cement system were investigated. Influence of dry coating on flowability of CaCO₃ was investigated by FT4 powder rheometer. The results indicate that flowability in presence of nano-additives improves with respect to pure CaCO₃. The activation energy of the calcination step was calculated by Kissinger-Akahira-Sunose method using themo-kinetic analysis. The results show that 1% w/w nano-additives (nano-TiO₂ and SiO₂) reduce the activation energy by 15 to 30% compared to original CaCO₃. Further, the reaction model for decomposition reaction was predicted by Master plot and Malekâ??s method and kinetic parameters were evaluated. The solid-solid reaction between CaO (originated from pure and nano-coated CaCO₃) and SiO₂ was then studied for formation kinetics of di-calcium silicate. The analysis of different phase formation was studied with the help of Rietveld refinement of XRD data. The results show that the reactivity of the CaO-SiO₂ system improves in presence of nano-additives which is explained by strain inside the crystal. Finally the stabilization of β-dicalcium silicate phase (desired cement phase) was studied. The results indicate that nano-TiO₂ effectively stabilize the β-phase which is explained by Hume-Rothery rules