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Current understanding of the state of Fe during the hydration of cement is very limited and further studies are necessary to find out the possible incorporation of Fe in cement hydrates. Moreover, it is important to understand the hydration reaction and properties development of ferrite-rich cement. Our previous study [1] reported the hydration reaction and properties of ferrite-rich Portland cement by various experimental techniques and thermodynamic modelling and compared with ordinary Portland cement. However, we could not quantify the Fecontaining hydrates in the cements and the uptake of Fe by C-S-H. Therefore, the objective of this study is to quantify the Fe-containing hydrates during the hydration of ordinary Portland cement and ferrite-rich Portland cement. Ordinary Portland cement and ferrite-rich Portland cement were hydrated for 3 months and the hydration products were quantified with XRD/Rietveld analysis. The selective dissolution was used to determine the amount of Fe-containing phases. It was found that Fe-siliceous hydrogarnet was the primary Fe-containing phase. From the hydration of ferrite and amount of formed Fesiliceous hydrogarnet, the Fe uptake in C-S-H was determined. The distribution ratio for Fe uptake in C-S-H and chemical composition of Fe-siliceous hydrogarnet were incorporated into the thermodynamic model to predict the hydration reaction of ordinary Portland cement and ferrite-rich Portland cement and the results were compared with experimental data of XRD/Rietveld analysis and selective dissolution. The successful agreement of the experimental results with the model demonstrates the state of Fe in the hydrated cements.

The hydration process in ferrite-rich cement (FC) and its pore structure have been investigated by experimental and thermodynamic modelling techniques. X-ray diffraction (XRD)/Rietveld analysis, thermogravimetry (TG), and mercury intrusion porosimetry (MIP) were performed to study the hydration process, pore volume-pore size distributions, and Fe uptake in calcium-silicate-hydrate (C-S-H). Similar phases were found in both FC and ordinary Portland cement (OPC). The hydration degree of FC was higher at the early stage compared with that of OPC; however, the hydration of OPC exceeded that of FC after 14 days because the high amount of C2S in OPC promoted the late hydration. The XRD-TG results revealed relatively similar Fe uptake by C-S-H in both FC and OPC. The thermodynamic model confirmed the formation of a high amount of Fe phases in FC. Moreover, the model predictions agreed well with the experimental results, demonstrating the accuracy of the proposed model for FC.

In this study, it is investigated the effect of Ca ion on dissolution and reaction products in alkaline environment using Pyrex glass showing ASR expansion and blast furnace slag fine aggregate suppressing ASR. It is reported that Ca plays a role in the dissolution and polymerization of silica, and is therefore an important factor in ASR. For each sample, calculation of dissolution rate and analysis of solid phase product by 29Si MAS NMR and XRD/Rietveld analysis, and liquid phase analysis by ICP-AES were performed. As a result, it was confirmed that addition of Ca has an influence on dissolution behavior of PG and BFS. In the reaction of PG, addition of Ca promotes the polymerization reaction of silica and increases the amount of N-S-H which has expandable and contributes to deterioration mechanism. On the other hand, in BFS, the dissolved silica did not polymerize and N-S-H did not form. It was suggested that the difference in ASR reactivity between PG and BFS is due to the difference in the reaction behavior.