Screening of Different Encapsulated Polymer-Based Healing Agents for Chloride Exposed Self-Healing Concrete Using Chloride Migration Tests

The service life of steel reinforced concrete in aggressive marine environments could be increased substantially by embedding a self-healing mechanism that ensures autonomous healing of cracks upon their occurrence. Previous proof-of-concept experiments have shown that the incorporation of encapsulated polymer-based healing agents (HAs) counts as a very appropriate way to achieve this goal. Over the years, several polymer-precursor-capsule systems have been developed in that perspective at our laboratory. Cementitious materials containing either commercial or in-house developed encapsulated HAs have been subjected to preliminary feasibility tests (water absorption, permeability tests, etc.). However, these experiments did not yet allow for a fast and straightforward assessment of the self-healing efficiency (SHE) in relation to the expected durability and service life performance of the material. This approach would have many advantages when having to select the most suitable polymer-precursor-capsule system for a particular concrete application. In this paper, a modified chloride migration test based on the one prescribed in NT Build 492 has been proposed to support the development of self-healing concrete for marine environments. Four polymer-based HAs have been screened that way, i.e. an in-house developed high-viscosity polyurethane (PU) precursor, a commercial low-viscosity PU precursor, the same commercial PU precursor with addition of accelerator and benzoyl peroxide (BPO), and an in-house developed 2-component acrylate-endcapped precursor + cross-linker. For now, a highly repeatable SHE value of 100% could only be obtained for the second option.

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Efficiency of self-healing cementitious materials with encapsulated polyurethane to reduce water ingress through cracks

Materiales de Construcción ◽

10.3989/mc.2018.05917 ◽

2018 ◽

Vol 68 (330) ◽

Cited By ~ 4

Author(s):

B. Van Belleghem ◽

K. Van Tittelboom ◽

N. De Belie

Keyword(s):

Large Range ◽

High Viscosity ◽

Cementitious Materials ◽

Self Healing ◽

Large Scatter ◽

Crack Healing ◽

Water Ingress ◽

Low Viscosity ◽

Healing Agent ◽

Concrete Elements

Cracks in reinforced concrete elements can cause major durability issues due do the accelerated ingress of aggressive substances. In this study, repair of cracks was addressed by incorporating encapsulated polyurethane based healing agents in the cementitious material as an autonomous healing mechanism. Capillary sorption tests showed that a high viscosity healing agent could reduce the water ingress in cracked mortar, but a large scatter in the results was found, resulting in a large range of healing efficiencies (18 – 108%). The low viscosity polyurethane showed a more complete and consistent crack healing. Healing efficiencies ranging from 95 to 124% were observed (crack width up to 295 μm). The proposed healing mechanism is very effective in blocking the ingress of water. This will enhance the durability of cementitious materials and consequently extend their lifetime.

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Expanding Boundaries - The Cost and Environmental Impact of Service Life Extending Self-Healing Engineered Materials for Sustainable Steel Reinforced Concrete – P. Van den Heede, B. Van Belleghem, N. De Belie

10.3218/3774-6_66 ◽

2016 ◽

Author(s):

Van den Heede, P. ◽

Van Belleghem, B. ◽

De Belie, N.

Keyword(s):

Reinforced Concrete ◽

Environmental Impact ◽

Service Life ◽

Self Healing ◽

Steel Reinforced Concrete ◽

Engineered Materials ◽

The Cost

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A Novel Organic–Inorganic Hybrid Admixture for Increasing Flowability and Reducing Viscosity of Ultra-High Performance Paste

Materials ◽

10.3390/ma13153385 ◽

2020 ◽

Vol 13 (15) ◽

pp. 3385 ◽

Cited By ~ 1

Author(s):

Min Wang ◽

Hao Yao

Keyword(s):

Steric Hindrance ◽

High Performance ◽

High Performance Concrete ◽

High Viscosity ◽

Inorganic Hybrid ◽

Oh Groups ◽

Low Viscosity ◽

Binder Ratio ◽

The One ◽

Water Binder Ratio

The low flowability and high viscosity of ultra-high performance concrete (UHPC), which is mainly caused by the silica fume (SF) agglomeration and low water–binder ratio, is a severe defect in its engineering applications. Herein, a novel organic–inorganic hybrid (OIH) admixture was synthesized by grafting comb-like polycarboxylate ether (PCE) onto the surface of SF. On the one hand, PCE-grafting could effectively prevent SF agglomeration and improve the dispersion of SF core. The reason being the consumption of polar silicon hydroxyl (Si-OH) groups on the surface of SF and the steric hindrance effect generated from PCE arms. On the other hand, OIH admixture could adsorb onto the surface of cement and SF particles by electrostatic interaction, exhibiting stronger steric hindrance effect than traditional comb-like PCE. As a result, UHPC system with this star-like OIH admixture presented high flowability and low viscosity at low water–binder ratio (0.18).

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Mount Etna and the 1971 eruption - Lengths of lava flows

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1973.0030 ◽

1973 ◽

Vol 274 (1238) ◽

pp. 107-118 ◽

Cited By ~ 342

Keyword(s):

Lava Flow ◽

High Viscosity ◽

Lava Flows ◽

Mount Etna ◽

High Rate ◽

Low Viscosity ◽

Depression Measurement ◽

Lateral Extent ◽

The One ◽

Single Flow

The principal factor influencing the length of a lava flow is the rate of effusion. With a high rate the lava flows rapidly from the source and tends to form an extensive and far-reaching flow which is simple in character (i.e. made of a single flow unit). With a low rate the lava tends to pile up layer upon layer to form a local accumulation of limited lateral extent near the source, and this accumulation is strongly compound in character (i.e. divisible into flow units). The initial viscosity affects the length indirectly by controlling the thickness of the extrusion, and this thickness control is capable of accounting for the fact that the median length of low-viscosity basaltic extrusions is 3.2 times that of high-viscosity andesite, trachyte and rhyolite ones. Other factors, such as the local topography, are thought to be relatively unimportant, an exception being when lava is ponded in a topographic depression. Measurement of the rate of effusion may be critical in any attempt to predict the distance that a lava flow will travel, such as the one which threatened Fornazzo and other towns and villages on Etna in 1971.

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Encapsulation Techniques and Test Methods of Evaluating the Bacteria-Based Self-Healing Efficiency of Concrete: A Literature Review

Nordic Concrete Research ◽

10.2478/ncr-2020-0006 ◽

2020 ◽

Vol 62 (1) ◽

pp. 63-85

Author(s):

Rahul Roy ◽

Emanuele Rossi ◽

Johan Silfwerbrand ◽

Henk Jonkers

Keyword(s):

Service Life ◽

Polymeric Materials ◽

Cementitious Materials ◽

Test Methods ◽

Self Healing ◽

Load Factors ◽

Healing Efficiency ◽

Healing Agent ◽

Maximum Crack ◽

Encapsulated Bacteria

AbstractCrack formation in concrete structures due to various load and non-load factors leading to degradation of service life is very common. Repair and maintenance operations are, therefore, necessary to prevent cracks propagating and reducing the service life of the structures. Accessibility to affected areas can, however, be difficult as the reconstruction and maintenance of concrete buildings are expensive in labour and capital. Autonomous healing by encapsulated bacteria-based self-healing agents is a possible solution. During this process, the bacteria are released from a broken capsule or triggered by water and oxygen access. However, its performance and reliability depend on continuous water supply, protection against the harsh environment, and densification of the cementitious matrix for the bacteria to act. There are vast methods of encapsulating bacteria and the most common carriers used are: encapsulation in polymeric materials, lightweight aggregates, cementitious materials, special minerals, nanomaterials, and waste-derived biomass. Self-healing efficiency of these encapsulated technologies can be assessed through many experimental methodologies according to the literature. These experimental evaluations are performed in terms of quantification of crackhealing, recovery of durability and mechanical properties (macro-level test) and characterization of precipitated crystals by healing agent (micro-level test). Until now, quantification of crack-healing by light microscopy revealed maximum crack width of 1.80mm healed. All research methods available for assesing self-healing efficiency of bacteria-based healing agents are worth reviewing in order to include a coherent, if not standardized framework testing system and a comparative evaluation for a novel incorporated bacteria-based healing agent.

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Comparison of Microbially Induced Healing Solutions for Crack Repairs of Cement-Based Infrastructure

Sustainability ◽

10.3390/su13084287 ◽

2021 ◽

Vol 13 (8) ◽

pp. 4287

Author(s):

John Milan van der Bergh ◽

Bojan Miljević ◽

Snežana Vučetić ◽

Olja Šovljanski ◽

Siniša Markov ◽

...

Keyword(s):

Compressive Strength ◽

Service Life ◽

Cementitious Materials ◽

Bacterial Suspension ◽

Self Healing ◽

Construction Costs ◽

Recovery Processes ◽

Concrete Crack ◽

Crack Repair ◽

Water Absorption Test

Reinforced concrete crack repair and maintenance costs are around 84% to 125% higher than construction costs, which emphasises the need to increase the infrastructure service life. Prolongation of the designed service life of concrete structures can have significant economic and ecological benefits by minimising the maintenance actions and related increase of carbon and energy expenditure, making it more sustainable. Different mechanisms such as diffusion, permeation and capillary action are responsible for the transport of fluids inside the concrete, which can impact on the structure service life. This paper presents data on microbially induced repair and self-healing solutions for cementitious materials available in the contemporary literature and compares results of compressive strength test and capillary water absorption test, which are relevant to their sealing and mechanical characteristics. The results of the repair and self-healing solutions (relative to unassisted recovery processes) were “normalized.” Externally applied bacteria-based solutions can improve the compressive strength of cementitious materials from 13% to 27%. The internal solution based solely on bacterial suspension had 19% improvement efficacy. Results also show that “hybrid” solutions, based on both bio-based and non-bio-based components, whether externally or internally applied, have the potential for best repair results, synergistically combining their benefits.

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A Low-Viscosity BisGMA Derivative for Resin Composites: Synthesis, Characterization, and Evaluation of Its Rheological Properties

Materials ◽

10.3390/ma14020338 ◽

2021 ◽

Vol 14 (2) ◽

pp. 338

Author(s):

Ali Alrahlah ◽

Abdel-Basit Al-Odayni ◽

Haifa Fahad Al-Mutairi ◽

Bashaer Mousa Almousa ◽

Faisal S. Alsubaie ◽

...

Keyword(s):

Substantial Reduction ◽

Triethylene Glycol ◽

High Viscosity ◽

Resin Matrix ◽

Resonance Spectroscopy ◽

Dental Resin ◽

Triethylene Glycol Dimethacrylate ◽

Oh Groups ◽

Low Viscosity ◽

13C Nuclear Magnetic Resonance

This study aimed to synthesize new bisphenol A-glycidyl methacrylate (BisGMA) derivatives, targeting a reduction in its viscosity by substituting one of its OH groups, the leading cause of its high viscosity, with a chlorine atom. Hence, this monochloro-BisGMA (mCl-BisGMA) monomer was synthesized by Appel reaction procedure, and its structure was confirmed using Fourier transform infrared spectroscopy, 1H and 13C-nuclear magnetic resonance spectroscopy, and mass spectroscopy. The viscosity of mCl-BisGMA (8.3 Pa·s) was measured under rheometry conditions, and it was found to be more than 65-fold lower than that of BisGMA (566.1 Pa·s) at 25 °C. For the assessment of the viscosity changes of model resins in the presence of mCl-BisGMA, a series of resin matrices, in which, besides BisGMA, 50 wt % was triethylene glycol dimethacrylate, were prepared and evaluated at 20, 25, and 35 °C. Thus, BisGMA was incrementally replaced by 25% mCl-BisGMA to obtain TBC0, TBC25, TBC50, TBC75, and TBC100 blends. The viscosity decreased with temperature, and the mCl-BisGMA content in the resin mixture increased. The substantial reduction in the viscosity value of mCl-BisGMA compared with that of BisGMA may imply its potential use as a dental resin matrix, either alone or in combination with traditional monomers. However, the various properties of mCl-BisGMA-containing matrices should be evaluated.

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A Conceptional Approach of Resin-Transfer-Molding to Rosin-Sourced Epoxy Matrix Green Composites

Aerospace ◽

10.3390/aerospace8010005 ◽

2020 ◽

Vol 8 (1) ◽

pp. 5

Author(s):

Sicong Yu ◽

Xufeng Zhang ◽

Xiaoling Liu ◽

Chris Rudd ◽

Xiaosu Yi

Keyword(s):

Composite Laminates ◽

Resin Transfer Molding ◽

High Viscosity ◽

Ramie Fiber ◽

Liquid Composite Molding ◽

Curing Agent ◽

Molding Process ◽

Transfer Molding ◽

Low Viscosity ◽

Composite Molding

In this concept-proof study, a preform-based RTM (Resin Transfer Molding) process is presented that is characterized by first pre-loading the solid curing agent onto the preform, and then injecting the liquid nonreactive resin with an intrinsically low viscosity into the mold to infiltrate and wet the pre-loaded preform. The separation of resin and hardener helped to process inherently high viscosity resins in a convenient way. Rosin-sourced, anhydrite-cured epoxies that would normally be regarded as unsuited to liquid composite molding, were thus processed. Rheological tests revealed that by separating the anhydrite curing agent from a formulated RTM resin system, the remaining epoxy liquid had its flowtime extended. C-scan and glass transition temperature tests showed that the preform pre-loaded with anhydrite was fully infiltrated and wetted by the liquid epoxy, and the two components were diffused and dissolved with each other, and finally, well reacted and cured. Composite laminates made via this approach exhibited roughly comparable quality and mechanical properties with prepreg controls via autoclave or compression molding, respectively. These findings were verified for both carbon and ramie fiber composites.

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