Novel experimental and numerical investigations on bonding behaviour of crack interface in smart self-healing concrete

Microcapsules are used in a wide range of applications, especially in self-healing composite materials and phase change materials. There is a growing body of literature that recognizes the importance of reinforcement on the mechanical properties of composites, however the effect of microcapsules during service needs to be further investigated. In this study, numerical investigations were conducted to examine the effects of the various geometric parameters on the mechanical behavior of microcapsules-based composites. The effective Young’s modulus and Poisson’s ratio of core-shell microcapsules distributed in a continuous matrix were predicted. A detailed three-dimensional finite element modeling (FEM) was presented. The numerical results were compared with a hierarchical proposed analytical model for three-constituent composites. Good agreements were achieved.

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Insights into Desiccation and Self-Healing of Bentonite in Geosynthetic Clay Liners under Thermal Loads

E3S Web of Conferences ◽

10.1051/e3sconf/20199203006 ◽

2019 ◽

Vol 92 ◽

pp. 03006

Author(s):

Abbas El-Zein ◽

Bowei Yu ◽

Ali Ghavam-Nasiri

Keyword(s):

Hydraulic Conductivity ◽

Mechanical Model ◽

Thermal Gradients ◽

Self Healing ◽

Transient Phase ◽

Geosynthetic Clay Liners ◽

Clay Liners ◽

Sodium Bentonite ◽

Mechanical Loads ◽

Numerical Investigations

Geosynthetic Clay Liners (GCLs) are widely used for protecting groundwater from pollution sources at the surface, including applications in which they are subject to significant thermal gradients. Hence, sodium bentonite in the GCL may undergo significant dehydration and cracking, and the GCL might fail as a result. The paper presents outcomes of a set of recent experimental and numerical investigations exploring the propensity of bentonite to desiccate and self-heal, as well as means of mitigating the effect of thermal gradients on the hydraulic conductivity of GCLs. An elasto-plastic thermo-hydro-mechanical model was found to yield reasonable predictions of experimental behaviour, except for the transient phase of pre-heating hydration. Introducing an airgap between the GCL and the heat source can reduce the extent of desiccation and its effects on hydraulic conductivity. However, the effectiveness of the solution will depend on other factors including subgrade, magnitude of thermal and mechanical loads and type of GCL.

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Healable thermoset polymer composite embedded with stimuli-responsive fibres

Journal of The Royal Society Interface ◽

10.1098/rsif.2012.0409 ◽

2012 ◽

Vol 9 (77) ◽

pp. 3279-3287 ◽

Cited By ~ 69

Author(s):

Guoqiang Li ◽

Harper Meng ◽

Jinlian Hu

Keyword(s):

Mechanical Properties ◽

Human Skin ◽

Biological Systems ◽

Healing Process ◽

Self Healing ◽

Stimuli Responsive ◽

Closed Crack ◽

Healing Efficiency ◽

Thermoset Polymer ◽

Crack Interface

Severe wounds in biological systems such as human skin cannot heal themselves, unless they are first stitched together. Healing of macroscopic damage in thermoset polymer composites faces a similar challenge. Stimuli-responsive shape-changing polymeric fibres with outstanding mechanical properties embedded in polymers may be able to close macro-cracks automatically upon stimulation such as heating. Here, a stimuli-responsive fibre (SRF) with outstanding mechanical properties and supercontraction capability was fabricated for the purpose of healing macroscopic damage. The SRFs and thermoplastic particles (TPs) were incorporated into regular thermosetting epoxy for repeatedly healing macroscopic damages. The system works by mimicking self-healing of biological systems such as human skin, close (stitch) then heal, i.e. close the macroscopic crack through the thermal-induced supercontraction of the SRFs, and bond the closed crack through melting and diffusing of TPs at the crack interface. The healing efficiency determined using tapered double-cantilever beam specimens was 94 per cent. The self-healing process was reasonably repeatable.

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Effect of Microcapsule Content on Diels-Alder Room Temperature Self-Healing Thermosets

Polymers ◽

10.3390/polym12123064 ◽

2020 ◽

Vol 12 (12) ◽

pp. 3064

Author(s):

Sadella C. Santos ◽

John J. La Scala ◽

Giuseppe R. Palmese

Keyword(s):

Urea Formaldehyde ◽

Average Diameter ◽

Diels Alder ◽

Phenyl Acetate ◽

Self Healing ◽

Healing System ◽

Diffusion Analysis ◽

Healing Efficiency ◽

Physical And Chemical ◽

Crack Interface

A furan functionalized epoxy-amine thermoset with an embedded microcapsule healing system that utilizes reversible Diels-Alder healing chemistry was used to investigate the influence of microcapsule loading on healing efficiency. A urea-formaldehyde encapsulation technique was used to create capsules with an average diameter of 150 µm that were filled with a reactive solution of bismaleimide in phenyl acetate. It was found that optimum healing of the thermoset occurred at 10 wt% microcapsule content for the compositions investigated. The diffusion of solvent through the crack interface and within fractured samples was investigated using analytical diffusion models. The decrease in healing efficiency at higher microcapsule loading was attributed partially to solvent-induced plasticization at the interface. The diffusion analysis also showed that the 10% optimum microcapsule concentration occurs for systems with the same interfacial solvent concentration. This suggests that additional physical and chemical phenomena are also responsible for the observed optimum. Such phenomena could include a reduction in surface area available for healing and the saturation of interfacial furan moieties by reaction with increasing amounts of maleimide. Both would result from increased microcapsule loading.

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Autonomous self-healing polyisoprene elastomers with high modulus and good toughness based on the synergy of dynamic ionic crosslinks and highly disordered crystals

Polymer Chemistry ◽

10.1039/d0py01034k ◽

2020 ◽

Vol 11 (41) ◽

pp. 6549-6558

Author(s):

Yohei Miwa ◽

Mayu Yamada ◽

Yu Shinke ◽

Shoichi Kutsumizu

Keyword(s):

Mechanical Properties ◽

Room Temperature ◽

Self Healing ◽

High Modulus ◽

Disordered Crystals ◽

Ionic Crosslinks

We designed a novel polyisoprene elastomer with high mechanical properties and autonomous self-healing capability at room temperature facilitated by the coexistence of dynamic ionic crosslinks and crystalline components that slowly reassembled.

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