Because of the inherent quasibrittleness and heterogeneity, matrix-directed toughening of concrete and cement composites remains to be a huge challenge. Herein, inspired by nacre materials, a novel biomimetic bulk cement composite is fabricated via a facile and efficient process based on compacting prefabricated multisized cement-polymer hybrid prills. This method combines with the three-dimensional "brick−bridge− mortar" structure design and synchronously the intrinsic and extrinsic toughening strategies. Such an approach shows the remarkable maximum toughness enhancement of 27-fold with 71% increase in flexural strength via cooperation with only 4 wt % organic matter. More attractively, it alters the traditional brittle fracture of cement composites to a distinct ductile fracture. In addition, such a biomimetic composite demonstrates the long-term ever-increasing strength and toughness, performing the excellent ductile-fracture retention ability. The hierarchical toughening mechanisms are further revealed with the synergy of microscopic characterizations and simulation methods. This strategy provides a new route for the development of high toughness biomimetic cement-based materials for potential applications in civil engineering domain.
Viscoelastic materials are commonly utilized in seismic vibration suppression of building structures. Supramolecular modification can extend the effective damping temperature range and improve the damping performance of viscoelastic materials. In present work, the mechanical behaviors of the nitrile rubber viscoelastic material are investigated by dynamic thermomechanical analyzer (DMA) with different strain amplitudes, excitation frequencies and environmental temperatures. The supramolecular interaction and molecular structures modified fractional Kelvin (SMF Kelvin) model taking into account the temperature and frequency impacts is proposed and verified with the DMA test results of the nitrile rubber viscoelastic material. The test results of the viscoelastic damper with different temperatures are employed to further prove the effectiveness of the new proposed SMF Kelvin model.
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