Impact of Hard Magnetic Nanocrystals on the Properties of Hardened Cement Paste

In this work, nano‐sized hard magnetic gallium‐substituted iron oxide crystals, wherein gallium is used to stabilize the metastable epsilon iron oxide phase, were added to cement‐water suspensions at different ratios, which were subsequently hydrated for at least 28 days. It is shown that higher contents of such nanocrystals in the hardened cement paste introduce a magnetic moment, whereas the mechanical properties remain unchanged compared to non‐blended hardened cement paste for a wide concentration range. The impact of different amounts of incorporated hard magnetic Ga0.043Fe1.957O3 (85 % ε and 15 % α phase) nanocrystals (NCs) on the physical properties of hardened cement paste is shown. By adding these Fe2O3 NCs it is possible to modify the manifold properties simultaneously, thus, enabling fine‐tuned buildings or coatings.