Nanocrystals and Cement

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

Nano-sized hard magnetic gallium-substituted iron oxide crystals 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.

Hardened cement pastes were prepared from a standard Portland cement (CEM I 42.5R) and different amounts of hard magnetic nanocrystals, and their structure-property relationships have been tested. Decisive physical properties of hardened cement paste were affected by the addition of this type of NCs:

  • The higher the Ga:Fe2O3 content, the higher the porosity and, consequently, the lower the sample density.

  • Coercive field HC and magnetic remanence MR are proportionally enhanced with rising Ga:Fe2O3 content, while the maximum magnetization at B = 7 T M7 T was only slightly affected.

  • Micro- and nanoscale mechanical properties remain unaffected, no matter how much Ga:Fe2O3 is added, while compressive strength decreases.

Original article:

P. A. Kißling, M. Mahlbacher, C. Wesemann, A. Mundstock, F. Lübkemann-Warwas, S. Klimke, F. Renz, L. Lohaus, M. Haist, and N. C. Bigall: Impact of Hard Magnetic Nanocrystals on the Properties of Hardened Cement PasteChem. Ing. Tech.2023,95, No. 00, 1–10
DOI: 10.1002/cite.202300022