Multi-layered cement-hydrogel composite with high toughness, low thermal conductivity, and self-healing capability

Abstract

The inherent quasi-brittleness of cement-based materials, due to the disorder of their hydration products and pore structures, present significant challenges for directional matrix toughening. In this work, a rigid layered skeleton of cement slurry was prepared using a simplified ice-template method, and subsequently flexible polyvinyl alcohol hydrogel was introduced into the unidirectional pores between neighboring cement platelets, resulting in the formation of a multi-layered cement-based composite. A toughness improvement of over 175 times is achieved by the implantation of such hard-soft alternatively layered microstructure. The toughening mechanism is the stretching of hydrogels at the nano-scale and deflections of micro-cracks at the interfaces, which avoid stress concentration and dissipate huge energy. Furthermore, this cement-hydrogel composite also exhibits a low thermal conductivity (around 1/10 of normal cement) and density, high specific strength and self-healing properties, which can be used in thermal insulation, seismic high-rise buildings and long-span bridges.

Effect of Modified Cellulose Nanocrystals on the Structure of Calcium Silicate Hydrate Studied by Molecular Dynamics Simulation and Experiment

“…The CVFF force field has been proved to be an effective empirical force field for analyzing the interactions between atoms of polar molecular, − CLAYFF force field often being used to describe the interface structure of cement matrix and water molecules. CVFFF and CLAYFF was combined used to describe the polar molecular and cement mineral system. , Therefore, this paper uses CVFF to describe CNC molecule and employs CLAYFF for CNC/C–S–H interfacial simulation. The detailed parameters of CVFF and CLAYFF are referred to and, respectively.…”

“…The interatomic distance affects the lifetime of the hydrogen bonds. Time correlation function (TCF) can analyze the stability of hydrogen bonds, a larger TCF means a more stable bonding. , As Figure shows, the stability of hydrogen bonds formed by CNCs follows the order that –COO – > –OH > –NH 2 > –SO 3 – . RDF analysis suggested that the atoms at CNC-C/C–S–H interface have the closest spatial correlation, and the distance between atoms affects the electrostatic adsorption; therefore, the hydrogen bond formed by CNC-C has the most stable performance.…”

“…CVFFF and CLAYFF was combined used to describe the polar molecular and cement mineral system. 43,44 Therefore, this paper uses CVFF to describe CNC molecule and employs CLAYFF for CNC/C−S−H interfacial simulation. The detailed parameters of CVFF and CLAYFF are referred to 45 and, 46 respectively.…”

Super stable evaporators based on upcycled self-healing adsorbents for wastewater regeneration

“…20,21 To enhance the mechanical stability, a "soft-hard synergistic" strategy can be employed whereby reinforcement materials are incorporated as rigid fillers into a soft amorphous matrix, resulting in a soft-hard dual-network structure. 22 Through the synergistic interplay between the rigid and soft components, material stress energy is dissipated significantly, thereby enhancing resistance to deformation and fracture. However, the contribution of this toughening method for improving mechanical performance is limited.…”

A toughening mechanism of the strain rate-optimal chain length on polymer-modified calcium silicate hydrates (CSH)

“…ceramics, glasses, and cements, usually have high mechanical strength but low toughness. 1 An elaborate incorporation of organic components into the inorganic matrix can substantially improve the toughness of the composites, meanwhile maintaining their high strength. For instance, the toughness of seashells is around 3 orders of magnitude higher than that of their component CaCO 3 crystals (aragonite), which results from the unique brick-mud arrangement, and organic polymers interspersed between the inorganic layers.…”