scholarly journals Self-Healing of Concrete Cracks by Ceramsite-Loaded Microorganisms

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Jing Xu ◽  
Xianzhi Wang ◽  
Junqing Zuo ◽  
Xiaoyan Liu
Keyword(s):  
Heat Treatment ◽  
Compressive Strength ◽  
Heating Temperature ◽  
Concrete Strength ◽  
The Self ◽  
Self Healing ◽  
Healing Efficiency ◽  
Maximum Crack ◽  
Harsh Conditions ◽  
Urea Decomposition

Protective carrier is essential for the self-healing of concrete cracks by microbially induced CaCO3 precipitation, owing to the harsh conditions in concrete. In this paper, porous ceramsite particles are used as microbial carrier. Heat treatment and NaOH soaking are first employed to improve the loading content of the ceramsite. The viability of bacterial spores is assessed by urea decomposition measurements. Then, the self-healing efficiency of concrete cracks by spores is evaluated by a series of tests including compressive strength regain, water uptake, and visual inspection of cracks. Results indicate that heat treatment can improve the loading content of ceramsite while not leading to a reduction of concrete strength by the ceramsite addition. The optimal heating temperature is 750°C. Ceramsite particles act as a shelter and protect spores from high-pH environment in concrete. When nutrients and spores are incorporated in ceramsite particles at the same time, nutrients are well accessible to the cells. The regain ratio of the compressive strength increases over 20%, and the water absorption ratio decreases about 30% compared with the control. The healing ratio of cracks reaches 86%, and the maximum crack width healed is near 0.3 mm.

scholarly journals Self-healing efficiency study of thermoset-thermoplastic polymer material

2022 ◽  
Vol 1217 (1) ◽  
pp. 012004
Author(s):  
W H Choong ◽  
H H Hamidi ◽  
K B Yeo
Keyword(s):  
Heat Treatment ◽  
Polymer Material ◽  
Impact Test ◽  
Structural Strength ◽  
Charpy Impact ◽  
Charpy Impact Test ◽  
The Self ◽  
Self Healing ◽  
Healing Efficiency ◽  
Material Formulation

Abstract This study is focused on exploring intrinsic self-healing polymer material development, where the inclusion of thermoplastic additives into thermoset polymer material as healing agents. Intrinsic self-healing thermoset-thermoplastic development is involving the material formulation of thermoset liquid resin (Poly Bisphenol A-co-epichlorohydrin) and thermoplastic (polycaprolactone). The material formulation ratio is up to 30% polycaprolactone with respect to thermoset weight. The mixture is heated and stirred to saturate at 80°C before the hardener is added. The mixture is cured and further finishing as Charpy impact test specimen. The specimen is fractured and absorbed impact energy property characterised through the Charpy impact test. The heat treatment is then performed to trigger the self-healing reaction in the polymer. The self-healing efficiency of the thermoset thermoplastic is investigated based on the absorbed impact energy before and after the heat treatment. The 20% or higher thermoplastic concentration in the polymer caused the polymer to possess high self-healing efficiency and faster healing time as compared to the low thermoplastic concentration polymer. However, the high concentration polymer has a disadvantage on the overall structural strength instead. On the contrary, 10% to 15% thermoplastic composition will result in lower and slower self-healing performance but higher initial structural strength.

Boronic Ester-Polyurethane as a Self-Healing Coating Material for Offshore Top Side Structures Application

2021 ◽  
Author(s):  
Mohd Shamsul Farid Samsudin ◽  
Norfarah Diana Aba ◽  
Muzdalifah Zakaria ◽  
Azmi Mohammed Nor ◽  
Russell Varley ◽  
...  
Keyword(s):  
Mechanical Performance ◽  
Coating Layer ◽  
Salt Spray ◽  
The Self ◽  
Self Healing ◽  
Humidity Level ◽  
Healing System ◽  
Healing Efficiency ◽  
Harsh Conditions

Abstract Polymer coatings, especially epoxy and polyurethane paint systems, have been widely used to prevent corrosion of metallic components and structures. However, due to environmental and mechanical effects, the barrier efficiency of the coatings may be substantially compromised during transportation and service, as demonstrated by localized scratches, delamination, or stress-related microcracks. Application of a self-healing coating that can restore damages and recover its performance with minimal external intervention could prevent corrosion at the damaged coating. In this present work, the healing efficiency and long-term durability of Boronic Ester (BE) blended with Polyurethane (PU) as a self-healing system for top side coating of offshore platform structures was investigated. The BE was mixed at a ratio of 50:50 with PU resin and applied as a top layer on a PU coated steel plate with a thickness of approximately 300-350 μm. The healing efficiency, mechanical performance, and durability under simulated environmental conditions such as salt spray and UV were investigated according to the related ASTM standards. As a first step, the electrical impedance spectroscopy (EIS) and 3D profilemeter microscope were used to assess the healing ability of the scratched coating at room temperature and humidity level of 85 %. The mechanical performance of the self-healing coating layer was evaluated using a pull off adhesion test to investigate the compatibility of the self-healing system with the existing commercial PU topcoat system, while a long term 3000 hours salt spray and 4200 hours cyclic UV test were performed to evaluate the self-healing coating's durability in harsh conditions. Preliminary assessment using EIS and 3D profilemeter microscopes on the scratched PU/BE self-healing coating revealed significant healing efficiency of more than 80% for healing condition at ambient temperature and humidity level of 85%. The self-healing coating layer also demonstrated excellent adhesion efficiency, with adhesion greater than 300 psi suggesting good compatibility of the BE-PU layer with commercial PU coating. The salt spray and cyclic UV tests that were performed to determine the durability of the self-healing coating revealed that the 50BE/50PU layer remained intact and exhibited good healing performance with more than 80% efficiency even after exposure to harsh conditions. The findings from the study demonstrated that the BE/PU material has the potential to be used as a self-healing system for topside coating of offshore platforms structures, thereby lowering maintenance costs.

Evaluating the Self-Healing Efficiency of Hydrogel-Encapsulated Bacteria in Concrete

2020 ◽  
Vol 2674 (6) ◽  
pp. 113-123 ◽  
Author(s):  
Ahsennur Soysal ◽  
Jose Milla ◽  
Gary M King ◽  
Marwa Hassan ◽  
Tyson Rupnow
Keyword(s):  
Alginate Beads ◽  
The Self ◽  
Self Healing ◽  
Bacterial Strains ◽  
Crack Sealing ◽  
Healing Efficiency ◽  
Maximum Crack ◽  
Encapsulated Bacteria ◽  
Curing Regime ◽  
Bacterial Concrete

Bacterial concrete has become one of the most promising self-healing alternatives owing to its capability to seal crack widths through microbial-induced calcite precipitation (MICP). In this study, two bacterial strains were embedded at varying dosages (by weight of cement) in concrete. Beam specimens were used to quantify the maximum crack-sealing efficiency, whereas cylinder samples were used to determine their effects on the intrinsic mechanical properties of concrete, as well as its stiffness recovery over time after inducing damage. The concrete specimens were cured in wet–dry cycles to enable healing. Results showed that the specimen groups with the highest calcium alginate concentrations (including the control specimens with embedded alginate beads but no bacteria) resulted in the greatest increase in stiffness recovery. Similarly, the beam samples containing alginate beads (also including the Control 3%C specimen group) had superior crack-healing efficiencies to the control samples without alginate beads (Control NC). This was attributed to the alginate beads acting as a reservoir that can further enhance the autogenous healing capability of concrete. Based on the results of this study, further research is recommended to explore factors that can maximize the self-healing mechanism of bacterial concrete through MICP and determine whether an alternative encapsulation mechanism, nutrient selection, curing regime, or bacterial strain is needed.

scholarly journals Application of bacteria in concrete: a critical evaluation of the current status

2016 ◽  
Vol 1 ◽  
pp. 56 ◽  
Author(s):  
Nele De Belie
Keyword(s):  
Concrete Strength ◽  
Critical Evaluation ◽  
Current Status ◽  
Carbonate Precipitation ◽  
Self Healing ◽  
Calcium Carbonate Precipitation ◽  
Healing Efficiency ◽  
New Strategy ◽  
Concrete Elements ◽  
Urea Decomposition

Microbially induced carbonate precipitation has been tested over more than a decade as a technique to enhance concrete properties. Mainly bacteria following the pathways of urea decomposition, oxidation of organic acids, or nitrate reduction have been studied for this purpose. For bacteria mixed into fresh concrete, it is difficult to prove that they actively contribute to calcium carbonate precipitation and the effects on concrete strength are variable. Application of bacteria for surface consolidation has been shown to reduce water absorption and increase durability. Microbial self-healing of cracks in concrete shows promising results at the laboratory scale. Especially the use of self-protected mixed cultures opens perspectives for practical application. However, their self-healing efficiency needs to be further proven in larger concrete elements, and under non-ideal conditions. The use of denitrifying cultures for concurrent self-healing and production of corrosion inhibiting nitrites is a promising new strategy.

Mechanical responses of microencapsulated self-healing cementitious composites under compressive loading based on a micromechanical damage-healing model

2021 ◽  
pp. 105678952110112
Author(s):  
Kaihang Han ◽  
Jiann-Wen Woody Ju ◽  
Yinghui Zhu ◽  
Hao Zhang ◽  
Tien-Shu Chang ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Compressive Strength ◽  
Micromechanical Model ◽  
Cementitious Composites ◽  
Self Healing ◽  
Damage Degree ◽  
Healing Efficiency ◽  
The Matrix ◽  
Healing Agent ◽  
Damage Healing

The cementitious composites with microencapsulated healing agents have become a class of hotspots in the field of construction materials, and they have very broad application prospects and research values. The in-depth study on multi-scale mechanical behaviors of microencapsulated self-healing cementitious composites is critical to quantitatively account for the mechanical response during the damage-healing process. This paper proposes a three-dimensional evolutionary micromechanical model to quantitatively explain the self-healing effects of microencapsulated healing agents on the damage induced by microcracks. By virtue of the proposed 3 D micromechanical model, the evolutionary domains of microcrack growth (DMG) and corresponding compliances of the initial, extended and repaired phases are obtained. Moreover, the elaborate studies are conducted to inspect the effects of various system parameters involving the healing efficiency, fracture toughness and preloading-induced damage degrees on the compliances and stress-strain relations. The results indicate that relatively significant healing efficiency, preloading-induced damage degree and the fracture toughness of polymerized healing agent with the matrix will lead to a higher compressive strength and stiffness. However, the specimen will break owing to the nucleated microcracks rather than the repaired kinked microcracks. Further, excessive higher values of healing efficiency, preloading-induced damage degree and the fracture toughness of polymerized healing agent with the matrix will not affect the compressive strength of the cementitious composites. Therefore, a stronger matrix is required. To achieve the desired healing effects, the specific parameters of both the matrix and microcapsules should be selected prudently.

Effect of Using Magnesium Acetate on the Self-Healing Efficiency of Hydrogel-Encapsulated Bacteria in Concrete

2021 ◽  
Author(s):  
Ricardo Hungria ◽  
Momen Mousa ◽  
Marwa Hassan ◽  
Omar Omar ◽  
Andrea Gavilanes ◽  
...  
Keyword(s):  
The Self ◽  
Magnesium Acetate ◽  
Self Healing ◽  
Healing Efficiency ◽  
Encapsulated Bacteria

scholarly journals Design of self-healing catalysts for aircraft application

2018 ◽  
Vol 9 (6) ◽  
pp. 723-736 ◽  
Author(s):  
Elisa Calabrese ◽  
Pasquale Longo ◽  
Carlo Naddeo ◽  
Annaluisa Mariconda ◽  
Luigi Vertuccio ◽  
...  
Keyword(s):  
Ruthenium Catalysts ◽  
The Self ◽  
Self Healing ◽  
Catalytic Systems ◽  
Content Type ◽  
Aerospace Applications ◽  
Healing Efficiency ◽  
Relevant Role ◽  
Aircraft Application

PurposeThe purpose of this paper is to highlight the relevant role of the stereochemistry of two Ruthenium catalysts on the self-healing efficiency of aeronautical resins.Design/methodology/approachHere, a very detailed evaluation on the stereochemistry of two new ruthenium catalysts evidences the crucial role of the spatial orientation of phenyl groups in the N-heterocyclic carbene ligands in determining the temperature range within the curing cycles is feasible without deactivating the self-healing mechanisms (ring-opening metathesis polymerization reactions) inside the thermosetting resin. The exceptional activity and thermal stability of the HG2MesPhSyncatalyst, with the syn orientation of phenyl groups, highlight the relevant potentiality and the future perspectives of this complex for the activation of the self-healing function in aeronautical resins.FindingsThe HG2MesPhSyncomplex, with the syn orientation of the phenyl groups, is able to activate metathesis reactions within the highly reactive environment of the epoxy thermosetting resins, cured up to 180°C, while the other stereoisomer, with the anti-orientation of the phenyl groups, does not preserve its catalytic activity in these conditions.Originality/valueIn this paper, a comparison between the self-healing functionality of two catalytic systems has been performed, using metathesis tests and FTIR spectroscopy. In the field of the design of catalytic systems for self-healing structural materials, a very relevant result has been found: a slight difference in the molecular stereochemistry plays a key role in the development of self-healing materials for aeronautical and aerospace applications.

scholarly journals Healing Performance of a Self-Healing Protective Coating According to Damage Width

Coatings ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 543
Author(s):  
Dong-Min Kim ◽  
Junseo Lee ◽  
Ju-Young Choi ◽  
Seung-Won Jin ◽  
Kyeong-Nam Nam ◽  
...  
Keyword(s):  
Protective Coating ◽  
Coating Thickness ◽  
Chloride Ion ◽  
The Self ◽  
Self Healing ◽  
Chloride Ion Penetration ◽  
Healing Efficiency ◽  
Sem Study ◽  
Capsule Size ◽  
Ion Penetration

Although self-healing protective coatings have been widely studied, systematic research on healing performance of the coating according to damage width has been rare. In addition, there has been rare reports of self-healing of the protective coating having damage width wider than 100 µm. In this study, self-healing performance of a microcapsule type self-healing protective coating on cement mortar was studied for the coating with damage width of 100–300 µm. The effect of capsule-loading (20 wt%, 30 wt% and 40 wt%), capsule size (65-, 102- and 135-µm-mean diameter) and coating thickness (50-, 80- and 100-µm-thick undercoating) on healing efficiency was investigated by water sorptivity test. Accelerated carbonation test, chloride ion penetration test and scanning electron microscope (SEM) study were conducted for the self-healing coating with a 300-µm-wide damage. Healing efficiency of the self-healing coating decreased with increasing damage width. As capsule-loading, capsule size or coating thickness increased, healing efficiency of the self-healing coating increased. Healing efficiency of 76% or higher was achieved using the self-healing coating with a 300-µm-wide scratch. The self-healing coating with a 200-µm-wide crack showed healing efficiency of 70% or higher. The self-healing coating having a 300-µm-wide scratch showed effective protection of the substrate mortar from carbonation and chloride ion penetration, which was supported by SEM study.

scholarly journals Self-Healable Supramolecular Vanadium Pentoxide Reinforced Polydimethylsiloxane-Graft-Polyurethane Composites

Polymers ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 41 ◽  
Author(s):  
Ali Berkem ◽  
Ahmet Capoglu ◽  
Turgut Nugay ◽  
Erol Sancaktar ◽  
Ilke Anac
Keyword(s):  
Tensile Strength ◽  
Vanadium Pentoxide ◽  
Coupling Reaction ◽  
Optical Microscope ◽  
Mechanical Tests ◽  
Healing Time ◽  
The Self ◽  
Supramolecular Polymer ◽  
Self Healing ◽  
Healing Efficiency

The self-healing ability can be imparted to the polymers by different mechanisms. In this study, self-healing polydimethylsiloxane-graft-polyurethane (PDMS-g-PUR)/Vanadium pentoxide (V2O5) nanofiber supramolecular polymer composites based on a reversible hydrogen bonding mechanism are prepared. V2O5 nanofibers are synthesized via colloidal route and characterized by XRD, SEM, EDX, and TEM techniques. In order to prepare PDMS-g-PUR, linear aliphatic PUR having one –COOH functional group (PUR-COOH) is synthesized and grafted onto aminopropyl functionalized PDMS by EDC/HCl coupling reaction. PUR-COOH and PDMS-g-PUR are characterized by 1H NMR, FTIR. PDMS-g-PUR/V2O5 nanofiber composites are prepared and characterized by DSC/TGA, FTIR, and tensile tests. The self-healing ability of PDMS-graft-PUR and composites are determined by mechanical tests and optical microscope. Tensile strength data obtained from mechanical tests show that healing efficiencies of PDMS-g-PUR increase with healing time and reach 85.4 ± 1.2 % after waiting 120 min at 50 °C. The addition of V2O5 nanofibers enhances the mechanical properties and healing efficiency of the PDMS-g-PUR. An increase of healing efficiency and max tensile strength from 85.4 ± 1.2% to 95.3 ± 0.4% and 113.08 ± 5.24 kPa to 1443.40 ± 8.96 kPa is observed after the addition of 10 wt % V2O5 nanofiber into the polymer.

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