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

Authors: 
Chandra Maiti, S., Indian Institute of Technology Gandhinagar
Ghoroi, C., Indian Institute of Technology Gandhinagar
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