The first microcapsule-based self-healing cement–bentonite cut-off wall materials

Cao, Benyi; Souza, Lívia Ribeiro de; Wang, Fei; Xu, Jiangang; Litina, Chrysoula; Al‐Tabbaa, Abir

doi:10.1680/jgeot.19.p.316

Cited by 5 publications

(3 citation statements)

References 29 publications

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“…Adjusting the material's viscosity and/or the capsules' density can reduce this anisotropy. Consequently, a number of authors have reported the uniform of capsules in cementitious matrices for both laboratory tests and in situ applications [50,76,77]. To further understand the performance of these new microcapsules, the encapsulation of healing agents, instead of model mineral oil as inner fluid, followed by quantification of self-healing performance is recommended.…”

Section: Production Of Microcapsules For Physically Triggered Self-he...mentioning

confidence: 99%

Biobased Acrylate Shells for Microcapsules Used in Self-Healing of Cementitious Materials

Souza

Whitfield²,

Al‐Tabbaa

2022

Sustainability

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To facilitate the ongoing transition towards carbon neutrality, the use of renewable materials for additive manufacturing has become increasingly important. Here, we report for the first time the fabrication of microcapsules from biobased acrylate shells using microfluidics. To select the shell, a wide range of biobased acrylates disclosed in the literature was considered according to their tensile strength, ductile transition temperature and global availability. Once acrylate epoxidised soybean oil (AESO) was selected, its viscosity was adjusted to valuables suitable for the microfluidic device using two different diluting agents. Double emulsions were successfully produced using microfluidics, followed by photopolymerisation of the shell and characterisation of the capsules. Microcapsules containing AESO and isobornyl acrylate (IBOA) were produced with an outer diameter ~490 μm, shell thickness ranging between 36 and 67 μm, and production rates around 2.4 g/h. The mechanical properties of the shell were characterised as tensile strength of 29.2 ± 7.7 MPa, Young’s modulus of 1.7 ± 0.4 GPa and the ductile transition temperature was estimated as 42 °C. To investigate physical triggering, microcapsules produced with a size of 481 ± 4 μm and with a measured shell thickness around 6 μm were embedded in the cementitious matrix. The triggered shells were observed with scanning electron microscopy (SEM) and the uniform distribution of the capsules in cement paste was confirmed using X-ray computed tomography (XCT). These advances can facilitate the wide application of biobased resins for the fabrication of microcapsules for self-healing in cementitious materials.

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Section: Production Of Microcapsules For Physically Triggered Self-he...mentioning

confidence: 99%

Biobased Acrylate Shells for Microcapsules Used in Self-Healing of Cementitious Materials

Souza

Whitfield²,

Al‐Tabbaa

2022

Sustainability

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“…Microcapsules are a critical component of many self-healing systems, enabling the incorporation and release of healing agents into structural materials to seal cracks [1][2][3]. Different healing agents have been encapsulated, including polymers, bacteria, and chemicals, such as sodium silicate and dicyclopentadiene, that can react with the host material or each other to re-bond crack faces [2][3][4]. Microcapsules for self-healing applications are commonly fabricated using emulsification techniques such as microfluidics [5], complex coacervation [6], in situ polymerisation [3], and interfacial polymerisation [6].…”

Section: Introductionmentioning

confidence: 99%

Microcapsule Triggering Mechanics in Cementitious Materials: A Modelling and Machine Learning Approach

Ricketts,

de Souza,

Freeman

et al. 2024

Materials

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Self-healing cementitious materials containing microcapsules filled with healing agents can autonomously seal cracks and restore structural integrity. However, optimising the microcapsule mechanical properties to survive concrete mixing whilst still rupturing at the cracked interface to release the healing agent remains challenging. This study develops an integrated numerical modelling and machine learning approach for tailoring acrylate-based microcapsules for triggering within cementitious matrices. Microfluidics is first utilised to produce microcapsules with systematically varied shell thickness, strength, and cement compatibility. The capsules are characterised and simulated using a continuum damage mechanics model that is able to simulate cracking. A parametric study investigates the key microcapsule and interfacial properties governing shell rupture versus matrix failure. The simulation results are used to train an artificial neural network to rapidly predict the triggering behaviour based on capsule properties. The machine learning model produces design curves relating the microcapsule strength, toughness, and interfacial bond to its propensity for fracture. By combining advanced simulations and data science, the framework connects tailored microcapsule properties to their intended performance in complex cementitious environments for more robust self-healing concrete systems.

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“…According to these theoretical solutions or numerical calculations, sensitivity analysis of various parameters for controlling contaminant transport can be carried out successfully [10]. These research studies on vertical transport behavior of contaminates in horizontal impermeable liners can provide references for calculating contaminant transport in the vertical impermeable cut-off wall [11]. Neville et al (2006) [12] established a steady-state transport model of contaminants in vertical impermeable cut-off wall and compared it with numerical simulation results.…”

Section: Introductionmentioning

confidence: 99%

Transport of Organic Contaminants in Composite Vertical Cut-Off Wall with Defective HDPE Geomembrane

et al. 2023

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Soil-bentonite vertical cut-off wall is an emergency technique used for contaminant control in geo-environmental engineering, high-density polyethylene (HDPE) geomembrane (GM) with an extremely low-permeability coefficient is expected to enhance the contaminant barrier effect of the vertical cut-off wall. To evaluate the barrier performance of the composite barrier composed of GM and soil-bentonite mixture towards organic contaminant, while also quantitively revealing the impact of GM defects and placement, a one-dimensional transport model for organic contaminants in composite barrier is solved under semi-infinite boundary conditions. The proposed transport model is validated by numerical simulations using COMSOL Multiphysics 5.4, and the effects of GM defect rate, placement within the composite isolation wall, and contact level with soil-bentonite on contaminant transport behavior are further studied. The results show that as the average frequency of GM defects increases from 2.5 to 50 holes per hectare, the breakthrough time of organic contaminants through composite barrier decreases by almost 70%. Poor contact level between GM and soil-bentonite mixture may reduce the breakthrough time of the composite cut-off wall by 65%. Although the selection of GM placement has limited impact on the transient flux of contaminants, it does affect the total flux of contaminants over a certain period of time. The effects of permeability coefficient, effective diffusion coefficient, distribution coefficient, and hydraulic head of the composite cut-off wall can be considered by the proposed analytical solution, which would provide guidance and reference for the design and service performance evaluation of the composite cut-off wall.

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The first microcapsule-based self-healing cement–bentonite cut-off wall materials

Cited by 5 publications

References 29 publications

Biobased Acrylate Shells for Microcapsules Used in Self-Healing of Cementitious Materials

Biobased Acrylate Shells for Microcapsules Used in Self-Healing of Cementitious Materials

Microcapsule Triggering Mechanics in Cementitious Materials: A Modelling and Machine Learning Approach

Transport of Organic Contaminants in Composite Vertical Cut-Off Wall with Defective HDPE Geomembrane

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