Impact of Bio-Carrier Immobilized with Marine Bacteria on Self-Healing Performance of Cement-Based Materials

The present study evaluated the self-healing efficiency and mechanical properties of mortar specimens incorporating a bio-carrier as a self-healing agent. The bio-carrier was produced by immobilizing ureolytic bacteria isolated from seawater in bottom ash, followed by surface coating with cement powder to prevent loss of nutrients during the mixing process. Five types of specimens were prepared with two methods of incorporating bacteria, and were water cured for 28 days. To investigate the healing ratio, the specimens with predefined cracks were treated by applying a wet–dry cycle in three different conditions, i.e., seawater, tap water, and air for 28 days. In addition, a compression test and a mercury intrusion porosimetry analysis of the specimens were performed to evaluate their physico-mechanical properties. The obtained results showed that the specimen incorporating the bio-carrier had higher compressive strength than the specimen incorporating vegetative cells. Furthermore, the highest healing ratio was observed in specimens incorporating the bio-carrier. This phenomenon could be ascribed by the enhanced bacterial viability by the bio-carrier.

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Recyclable Self-Healing Polyurethane Cross-Linked by Alkyl Diselenide with Enhanced Mechanical Properties

Polymers ◽

10.3390/polym11050773 ◽

2019 ◽

Vol 11 (5) ◽

pp. 773 ◽

Cited By ~ 3

Author(s):

Yuqing Qian ◽

Xiaowei An ◽

Xiaofei Huang ◽

Xiangqiang Pan ◽

Jian Zhu ◽

...

Keyword(s):

Mechanical Properties ◽

Room Temperature ◽

Amide Bond ◽

Self Healing ◽

Healing Efficiency ◽

Polyurethane Networks ◽

Combined Action ◽

Cross Linker ◽

Dynamic Structures ◽

External Interventions

Dynamic structures containing polymers can behave as thermosets at room temperature while maintaining good mechanical properties, showing good reprocessability, repairability, and recyclability. In this work, alkyl diselenide is effectively used as a dynamic cross-linker for the design of self-healing poly(urea–urethane) elastomers, which show quantitative healing efficiency at room temperature, without the need for any catalysts or external interventions. Due to the combined action of the urea bond and amide bond, the material has better mechanical properties. We also compared the self-healing effect of alkyl diselenide-based polyurethanes and alkyl disulfide-based polyurethanes. The alkyl diselenide has been incorporated into polyurethane networks using a para-substituted amine diphenyl alkyl diselenide. The resulting materials not only exhibit faster self-healing properties than the corresponding disulfide-based materials, but also show the ability to be processed at temperatures as low as 60 °C.

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Evaluation of the Katz-Thompson model for estimating the water permeability of cement-based materials from mercury intrusion porosimetry data

Cement and Concrete Research ◽

10.1016/0008-8846(94)90131-7 ◽

1994 ◽

Vol 24 (3) ◽

pp. 443-455 ◽

Cited By ~ 72

Author(s):

A.S. El-Dieb ◽

R.D. Hooton

Keyword(s):

Water Permeability ◽

Mercury Intrusion Porosimetry ◽

Mercury Intrusion ◽

Cement Based Materials

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Numerical Studies of the Effects of Water Capsules on Self-Healing Efficiency and Mechanical Properties in Cementitious Materials

Advances in Materials Science and Engineering ◽

10.1155/2016/8271214 ◽

2016 ◽

Vol 2016 ◽

pp. 1-10 ◽

Cited By ~ 1

Author(s):

Haoliang Huang ◽

Guang Ye

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Elastic Modulus ◽

Cementitious Materials ◽

Self Healing ◽

Negative Effects ◽

Numerical Studies ◽

Healing Efficiency ◽

The Impact ◽

Positive Effect

In this research, self-healing due to further hydration of unhydrated cement particles is taken as an example for investigating the effects of capsules on the self-healing efficiency and mechanical properties of cementitious materials. The efficiency of supply of water by using capsules as a function of capsule dosages and sizes was determined numerically. By knowing the amount of water supplied via capsules, the efficiency of self-healing due to further hydration of unhydrated cement was quantified. In addition, the impact of capsules on mechanical properties was investigated numerically. The amount of released water increases with the dosage of capsules at different slops as the size of capsules varies. Concerning the best efficiency of self-healing, the optimizing size of capsules is 6.5 mm for capsule dosages of 3%, 5%, and 7%, respectively. Both elastic modulus and tensile strength of cementitious materials decrease with the increase of capsule. The decreasing tendency of tensile strength is larger than that of elastic modulus. However, it was found that the increase of positive effect (the capacity of inducing self-healing) of capsules is larger than that of negative effects (decreasing mechanical properties) when the dosage of capsules increases.

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

International Journal of Damage Mechanics ◽

10.1177/10567895211011239 ◽

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.

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Influence of Coarse Aggregates and Silica Fume on the Mechanical Properties, Durability, and Microstructure of Concrete

Materials ◽

10.3390/ma12203324 ◽

2019 ◽

Vol 12 (20) ◽

pp. 3324 ◽

Cited By ~ 4

Author(s):

Seong Soo Kim ◽

Abdul Qudoos ◽

Sadam Hussain Jakhrani ◽

Jeong Bae Lee ◽

Hong Gi Kim

Keyword(s):

Electron Microscopy ◽

Mechanical Properties ◽

Silica Fume ◽

Mercury Intrusion Porosimetry ◽

Construction Material ◽

Chloride Penetration ◽

Mercury Intrusion ◽

Coarse Aggregates ◽

Overall Performance ◽

Scanning Electron

Globally, concrete is the most widely used construction material. The composition of concrete plays an important role in controlling its overall performance. Concrete is composed of approximately 70%–80% aggregates, by volume. Therefore, it is mandatory to investigate the effect of aggregates on the performance of concrete. For this purpose, this study investigated the effect of three different coarse aggregates on the mechanical properties, durability, and microstructure of concrete. Concrete specimens were made using aggregates obtained from three regions with different mineralogies. The specimens were also made by replacing cement with silica fume. The specimens were analyzed in terms of compressive, flexural, and splitting tensile strengths, chloride penetration, carbonation, mercury intrusion porosimetry, and scanning electron microscopy. The results demonstrate that the specimens made with rougher coarse aggregates and silica fume had enhanced performance in comparison to those made with smoother aggregates.

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Dynamic Mussel-Inspired Chitin Nanocomposite Hydrogels for Wearable Strain Sensors

Polymers ◽

10.3390/polym12061416 ◽

2020 ◽

Vol 12 (6) ◽

pp. 1416 ◽

Cited By ~ 3

Author(s):

Pejman Heidarian ◽

Abbas Z. Kouzani ◽

Akif Kaynak ◽

Ali Zolfagharian ◽

Hossein Yousefi

Keyword(s):

Mechanical Properties ◽

Polyacrylic Acid ◽

Strain Sensors ◽

Self Healing ◽

Network Stability ◽

Ferric Ions ◽

Trade Off ◽

Nanocomposite Hydrogels ◽

Healing Efficiency ◽

Hydrogel Network

It is an ongoing challenge to fabricate an electroconductive and tough hydrogel with autonomous self-healing and self-recovery (SELF) for wearable strain sensors. Current electroconductive hydrogels often show a trade-off between static crosslinks for mechanical strength and dynamic crosslinks for SELF properties. In this work, a facile procedure was developed to synthesize a dynamic electroconductive hydrogel with excellent SELF and mechanical properties from starch/polyacrylic acid (St/PAA) by simply loading ferric ions (Fe3+) and tannic acid-coated chitin nanofibers (TA-ChNFs) into the hydrogel network. Based on our findings, the highest toughness was observed for the 1 wt.% TA-ChNF-reinforced hydrogel (1.43 MJ/m3), which is 10.5-fold higher than the unreinforced counterpart. Moreover, the 1 wt.% TA-ChNF-reinforced hydrogel showed the highest resistance against crack propagation and a 96.5% healing efficiency after 40 min. Therefore, it was chosen as the optimized hydrogel to pursue the remaining experiments. Due to its unique SELF performance, network stability, superior mechanical, and self-adhesiveness properties, this hydrogel demonstrates potential for applications in self-wearable strain sensors.

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Adaptable Eu-containing polymeric films with dynamic control of mechanical properties in response to moisture

Soft Matter ◽

10.1039/c9sm02440a ◽

2020 ◽

Vol 16 (9) ◽

pp. 2276-2284 ◽

Cited By ~ 7

Author(s):

Zichao Wei ◽

Srinivas Thanneeru ◽

Elena Margaret Rodriguez ◽

Gengsheng Weng ◽

Jie He

Keyword(s):

Mechanical Properties ◽

Optical Properties ◽

Polymer Films ◽

Dynamic Control ◽

Polymeric Films ◽

Self Healing ◽

Healing Efficiency

Moisture that competes with dipicolylamine to bind Eu dynamically controls the mechanical and optical properties of polymer films, as well as their self-healing efficiency.

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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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Meta-Analysis and Machine Learning Models to Optimize the Efficiency of Self-Healing Capacity of Cementitious Material

Materials ◽

10.3390/ma14164437 ◽

2021 ◽

Vol 14 (16) ◽

pp. 4437

Author(s):

Shashank Gupta ◽

Salam Al-Obaidi ◽

Liberato Ferrara

Keyword(s):

Meta Analysis ◽

Cementitious Materials ◽

Initial Crack ◽

Supplementary Cementitious Materials ◽

Structural Performance ◽

Self Healing ◽

Design Strategies ◽

Healing Efficiency ◽

Cement Based Materials ◽

Artificial Neural Network Ann

Concrete and cement-based materials inherently possess an autogenous self-healing capacity. Despite the huge amount of literature on the topic, self-healing concepts still fail to consistently enter design strategies able to effectively quantify their benefits on structural performance. This study aims to develop quantitative relationships through statistical models and artificial neural network (ANN) by establishing a correlation between the mix proportions, exposure type and time, and width of the initial crack against suitably defined self-healing indices (SHI), quantifying the recovery of material performance. Furthermore, it is intended to pave the way towards consistent incorporation of self-healing concepts into durability-based design approaches for reinforced concrete structures, aimed at quantifying, with reliable confidence, the benefits in terms of slower degradation of the structural performance and extension of the service lifespan. It has been observed that the exposure type, crack width and presence of healing stimulators such as crystalline admixtures has the most significant effect on enhancing SHI and hence self-healing efficiency. However, other parameters, such as the amount of fibers and Supplementary Cementitious Materials have less impact on the autogenous self-healing. The study proposes, through suitably built design charts and ANN analysis, a straightforward input–output model to quickly predict and evaluate, and hence “design”, the self-healing efficiency of cement-based materials.

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