Understanding the role of magneto-rheological control in modifying the mechanical characteristics of cement pastes

This study aims to clarify the mechanisms by which magnetic field exposure affects the mechanical performance and microstructural evolution of cement pastes incorporating magnetic particles. Cement pastes with different water-to-cement (w/c) ratios and curing ages were prepared using fine and coarse Fe₃O₄ particles and subjected to magnetic fields with varying intensities. Directional compressive strength testing was conducted to evaluate mechanical anisotropy, while X-ray diffraction (XRD), mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) were employed to examine the corresponding microstructural characteristics. The results indicate that the magneto-rheological (MR) response of cement pastes strongly depends on magnetic field intensity and particle size, with particles of 18 μ m providing greater rheological modulation even under low field intensity (25–60 mT). Moreover, the directional alignment of magnetic particles causes anisotropic mechanical behavior, most pronounced at early ages under stronger field intensity (70–115 mT) and persisting at 28 days only for a w/c ratio of 0.45 with 10 % particle content. In addition, the magnetic field gradients promote the Fe₃O₄ particle migration toward high-flux regions, causing spatial heterogeneity in hydration products and pore structure. The findings provide useful recommendations for balancing effective fresh-state MR control with minimal adverse effects on hardened properties, offering valuable guidance for optimizing magnetic particle incorporation and field application in advanced construction practices. © 2025 Elsevier Ltd. All rights are reserved