Stress concentrations and bonding strength in encapsulation-based self-healing materials

Gilabert, F.A.; Garoz, D.; Paepegem, Wim Van

doi:10.1016/j.matdes.2014.11.012

Cited by 44 publications

(39 citation statements)

References 29 publications

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“…On the other hand, when a PCM particle is introduced into the paste, the softer (than paste) PCM particle experiences negligible stresses ( Figure 10(b)), and the stress is concentrated at the PCM-paste interface. Similar observations are reported for soft particles elsewhere [60]. Note that the PCM shell is very strong (~250 MPa) and the interface between paste and PCM-E is assumed to be slightly stronger than the bulk paste (see the following section).…”

Section: The Influence Of Inclusion Characteristics On Stress Distribsupporting

confidence: 80%

The influence of microencapsulated phase change material (PCM) characteristics on the microstructure and strength of cementitious composites: Experiments and finite element simulations

Aguayo

Das

Maroli

et al. 2016

Cement and Concrete Composites

151

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Phase Change Materials (PCMs) incorporated into cementitious systems have been well-studied with respect to energy efficiency of building envelopes. New applications of PCMs in infrastructural concrete, e.g., for mitigating early-age cracking and freeze-and-thaw induced damage, have been proposed. Hence this paper develops a detailed understanding of the characteristics of cementitious systems containing two different microencapsulated PCMs. The PCMs are evaluated using thermal analysis, vibrational (FTIR) spectroscopy, and electron microscopy, and their dispersion in cement pastes is quantified using X-ray Computed Microtomography (µCT). The influences of PCMs on cement hydration and pore structure are evaluated. The compressive strength of mortars containing PCMs is noted to be strongly dependent on the encapsulation properties. Finite element simulations carried out on cementitious microstructures are used to assess the influence of interface properties and inter-inclusion interactions.The outcomes provide insights on methods to tailor the component phase properties and PCM volume fraction so as to achieve desirable performance.

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Section: The Influence Of Inclusion Characteristics On Stress Distribsupporting

confidence: 80%

The influence of microencapsulated phase change material (PCM) characteristics on the microstructure and strength of cementitious composites: Experiments and finite element simulations

Aguayo

Das

Maroli

et al. 2016

Cement and Concrete Composites

151

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“…In terms of designing a predictive tool, the interest in encapsulationbased self-healing strategy is currently leading to an increase of theoretical and numerical works with the aim of getting a better understanding of its mechanisms and determining the key factors to improve efficiency and feasibility [11][12][13][14][15]. In spite of this, most models deal with very specific application-oriented materials and also assume specific geometries, boundary conditions and loading configuration.…”

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confidence: 99%

Macro- and micro-modeling of crack propagation in encapsulation-based self-healing materials: Application of XFEM and cohesive surface techniques

2017

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A B S T R A C TEncapsulation-based materials are produced introducing some small healing fluid-filled capsules in a matrix. These materials can self-heal when internal cracks intercept and break the capsules. If the healing agent is released, the crack can be sealed. However, this is not always the case. These capsules need to be designed with the adequate shape and material to be properly broken. This paper presents two application models based on the combination of eXtended Finite Element Method (XFEM) elements and Cohesive Surfaces technique (CS) to predict crack propagation. Two types of encapsulated systems are considered: a concrete beam in a three-point bending test, and a micro-scale model of a representative volume element of a polymer subjected to a uniaxial tensile test. Despite both systems relying on different capsule shapes and different constituent materials, the models predict a similar non-linear response of the overall material strength governed by the coupled effect of the interface strength and the capsule radii-to-thickness ratio. Furthermore, even if an inadequate material and geometry combination is used, it is found that the mere presence of capsules might achieve, under certain conditions, an interesting overall reinforcement effect. This effect is discussed in terms of clustering and volume fraction of capsules.

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“…The mechanical properties of this interface have received less attention, and its properties have not been the main object of mechanical characterization. However, the current interest in this self-healing strategy is leading to an increase of theoretical and numerical works with the aim of getting a better understanding of its mechanisms and determining the key factors to improve efficiency and feasibility [8,[21][22][23][24][25][26][27]. These models assume either perfect bonding or a certain range of typical values of the interface properties, which are selected as a function of mechanical similarities given by composition or the degree of brittleness [28,29].…”

Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 99%

“…As an example, the analysis of the effect of the capsule shape (e.g., spherical, tubular) and size (length, diameter, thickness) on the capability of its debonding or fracture within the matrix can be carried out. The properties obtained from the present paper can be directly used to feed traction-separation laws using cohesive elements in finite element models [25,27,31,32]. From the practical point of view, if the capsule-matrix interface strength has to be increased but the capsules surfaces cannot be previously treated with additives, its geometrical features could be chosen in such a way that it triggers the capsule breakage more easily under certain types of stress fields.…”

Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 99%

“…This energy, also referred to as fracture toughness, represents the energy that has been dissipated during the full detachment of the two initially attached surfaces. Regarding the interface stiffness K * , as it has been checked previously [27], Abaqus calculates automatically the adequate value as a function of the two solid material elements under interaction. This ensures that stiffness of the interface does not alter the global stiffness of the system concrete-glass.…”

Section: Regionmentioning

confidence: 99%

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Determination of strength and debonding energy of a glass-concrete interface for encapsulation-based self-healing concrete

Gilabert

Tittelboom

Tsangouri

et al. 2017

Cement and Concrete Composites

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This paper presents a combined experimental-numerical analysis to assess the strength and fracture toughness of a glass-concrete interface. This interface is present in encapsulation-based self-healing concrete. There is absence of published results of these two properties, despite their important role in the correct working of this self-healing strategy. Two setups are used: uniaxial tensile tests to assess the bonding strength and four point bending tests to get the interfacial energy. The complementary numerical models for each setup are conducted using the finite element method. Two approaches are used: cohesive zone model to study the interface strength and the virtual crack closure technique to analyze the interfacial toughness. The models are validated and used to verify the experimental interpretations. It is found that a glass-concrete interface can develop a maximum strength of approximately 1 N/mm 2 with fracture energy of 0.011 J/m 2 .

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Stress concentrations and bonding strength in encapsulation-based self-healing materials

Cited by 44 publications

References 29 publications

The influence of microencapsulated phase change material (PCM) characteristics on the microstructure and strength of cementitious composites: Experiments and finite element simulations

The influence of microencapsulated phase change material (PCM) characteristics on the microstructure and strength of cementitious composites: Experiments and finite element simulations

Macro- and micro-modeling of crack propagation in encapsulation-based self-healing materials: Application of XFEM and cohesive surface techniques

Determination of strength and debonding energy of a glass-concrete interface for encapsulation-based self-healing concrete

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