Self-healing Potential Research Articles

Improving the Protection Performance of Waterborne Coatings with a Corrosion Inhibitor Encapsulated in Polyaniline-Modified Halloysite Nanotubes

Organic coatings provide an effective way to improve the corrosion resistance of metals. Traditional organic varnishes, however, either contain highly polluting or toxic components or lack self-healing ability. In this article, we report a feasible method of preparing polyaniline-modified halloysite nanotubes (PANI@HNTs). They were loaded with a corrosion inhibitor, benzotriazole (BTA), and were tested as multifunctional anticorrosion additives for environmentally friendly epoxy waterborne coatings. The PANI@HNTs were formed via the in situ polymerization of aniline in the presence of halloysites. The BTA loading was then carried out and reached up to 14.5 wt.%. The BTA retention ability of the PANI@HNTs was significantly improved in comparison to that of pure HNT. Electrochemical impedance spectroscopy (EIS) tests of the coatings immersed in a 3.5 wt.% NaCl solution showed that the barrier and corrosion inhibition effects were enhanced by two to four orders of magnitude with the incorporation of BTA-loaded PANI@HNTs. The salt spray tests on artificially scratched coatings revealed that the surfaces protected by varnishes doped with the BTA-loaded PANI@HNTs exhibited the lowest degree of corrosion compared to the control samples, illustrating the self-healing potential of the modified coatings.

Evaluation of the impact of nanomodification on Self-Healing behavior of asphalt binders

Nanomaterials, due to their higher surface area, smaller particle size, and unique chemical characteristics, might be a potential additive to self-heal microcracks in asphalt pavement and extend pavement life. The goal of this study is to examine the self-healing potential of asphalt binder modified with nanosilica, nanoalumina, and nanoclay at three different dosages. First, factors affecting self-healing behavior (i.e., blending techniques, rest period, and damage level) were investigated following Performance grade, Surface Free Energy, Storage stability, and Fourier Transform Infrared Spectroscopy tests. 1% nanosilica exhibited the highest self-healing potential, while 3% nanoalumina also performed well at higher damage levels.

Experimental realization of Airy beams on incoherent background

We report an experimental realization of recently introduced Airy beams on incoherent background (ABIBs). The ABIBs are structured random beams that defy diffraction in free space, making them attractive to free-space optical communications, information transfer and imaging. We demonstrate here that the (truncated) laboratory realizations of ABIBs are more resilient to diffraction and far more capable of self-healing after having been obstructed by defects than are truncated coherent Airy beams of the same width of the main lobe and truncation length. The combination of remarkable propagation invariance and self-healing potential of ABIBs carries promise for their applications to optical communications in randomly inhomogeneous environments and biological tissue imaging.

Measuring Bone Healing: Parameters and Scores in Comparison.

(1) Background: Bone healing is a complex process that can not be replicated in its entirety in vitro. Research on bone healing still requires the animal model. The critical size femur defect (CSFD) in rats is a well-established model for fractures in humans that exceed the self-healing potential. New therapeutic approaches can be tested here in vivo. Histological, biomechanical, and radiological parameters are usually collected and interpreted. However, it is not yet clear to what extent they correlate with each other and how necessary it is to record all parameters. (2) Methods: The basis for this study was data from three animal model studies evaluating bone healing. The µCT and histological (Movat pentachrome, osteocalcin) datasets/images were reevaluated and correlation analyses were then performed. Two image processing procedures were compared in the analysis of the image data. (3) Results: There was a significant correlation between the histologically determined bone fraction (Movat pentachrome staining) and bending stiffness. Bone fraction determined by osteocalcin showed no prognostic value. (4) Conclusions: The evaluation of the image datasets using ImageJ is sufficient and simpler than the combination of both programs. Determination of the bone fraction using Movat pentachrome staining allows conclusions to be drawn about the biomechanics of the bone. A standardized procedure with the ImageJ software is recommended for determining the bone proportion.

Experimental Study on Bacterial based Self-Healing Concrete

Abstract: The potential of concrete to self-heal has been studied in several works, hence in this study we are analyzing the strength properties of self-healing bacterial concrete by mixing bacteria (Bacillus Subtilis) with calcium source. In the study, bacteria (Bacillus Subtilis) were introduced at 3% and 5%, while calcium lactate was added at 5% and 10%, respectively. As a result, the study addresses economic issues not just for building but also for upkeep. The purpose of this experiment was to look into the strength qualities of bacterial self-healing concrete with varied ratios of Bacillus subtilis and calcium lactate. The researchers prepared concrete specimens with varied ratios of bacterial solution and calcium lactate and tested their compressive and flexural strength. The results revealed that adding Bacillus subtilis and calcium lactate to the concrete enhanced its compressive and flexural strength, with the maximum strength values recorded at a 3% bacterial solution and 5% calcium lactate combination. Furthermore, the concrete's self-healing potential was assessed by putting the samples to crack-healing experiments. The results demonstrated that the bacterial self-healing concrete containing Bacillus subtilis and calcium lactate performed better than the control samples without bacteria. The study reveals that using Bacillus subtilis and calcium lactate in concrete might increase the material's strength and self-healing capabilities, leading to enhanced durability and sustainability of concrete buildings.

Extrinsic Conditions for the Occurrence and Characterizations of Self-Healing Polyurea Coatings for Improved Medical Device Reliability: A Mini Review.

The development of self-healing materials has gained significance in the medical field to enhance the longevity and reliability of medical devices and implants. Material degradation caused by mechanical stress, environmental factors, and damage during use can lead to failure and necessitate manual inspection and maintenance. Self-healing materials, including polymers and elastomers, offer a promising solution by activating microdamage repair mechanisms. Polyurea coatings, known for their durability, flexibility, and versatility, have found widespread applications in various industries to prevent corrosion and abrasion and impact damage. This review focuses on the self-healing capability of polyurethane coatings and the efficacy of fabricated microcapsules. Experimental results elucidate the necessary conditions for achieving self-healing in polyurethane coatings encapsulated with suitable healing agents. These factors directly impact the self-healing potential of polyurea coatings and provide insights for medical device manufacturers seeking optimal coatings. The report also discusses challenges in fabrication and sample preparation, along with limitations of the project and recommendations for future research.

Forecasting the self-healing capacity of engineered cementitious composites using bagging regressor and stacking regressor

Engineered cementitious composite (ECC) is a unique product that can significantly contribute to self-healing when continuously hydrated. To measure its self-healing capacity, it is necessary to evaluate the crack-width once the healing process is complete. ECC has a remarkable ability to self-heal, but predicting its self-healing potential is challenging. In this study, two different ensemble machine learning (ML) algorithms i.e. bagging regressor (BR) and stacking regressor (SR) were employed to estimate ECC’s self-healing capacity. Model effectiveness was assessed using error analysis and k-fold cross-validation methods. The SR model had a higher R2 and was more successful in predicting the outcomes than the BR model. However, both ensemble models with smaller error values also showed improved model performance. Furthermore, the crack-healing characteristics of wheat straw ash, rice husk ash, and pumice powder are recommended to be evaluated in future studies using ML methods.

Presenting the Self-Healing Potential Model by Induction Heating Method in Warm Asphalt Mixtures by Artificial Neural Network

The increasing number of vehicles in the world and the increase in the dimensions of light and heavy vehicles with different combinations, including simple and compound axles, have caused various types of damage in the asphalt, which affects the performance of the roads and requires a suitable pavement. For this reason, engineers try to improve the performance of asphalt mixture in different ways and increase their useful life. Cracking is one of the main failure modes of asphalt pavements. Fatigue cracking is the most common form of asphalt failure and is one of the important factors in reducing the life of road pavements. The purpose of this research is to investigate the index of self-healing potential (HI) of asphalt mixtures containing activated carbon and zycotherm by induction heating method and modelling by artificial neural network. First, by making warm mixture asphalt samples containing activated carbon, self-healing by induction heating method was provided in the pavement, and then the effect of traffic loading and environmental conditions simultaneously in terms of changes in loading parameters, taking into account the conditions of the service life. The results show that the use of activated carbon increases the values of shear modulus. It also improves the properties of modified bitumen at all temperatures. The resistance of the asphalt mixture against breaking and cracking, as well as the maximum force tolerance at the temperature of -16°C is higher than at the temperature of 25°C, which is one of the reasons for the reduction of flexibility of bitumen at low temperature. Also, for modelling, perceptron multi-layer neural network (MLP) with 9 input variables, three hidden layers and one output layer has been used. The results showed that the explanation coefficient of the neural network model for training, validation and evaluation data was 0.99717 for training, 0.62053 for validation and 0.9301 for testing. These values correctly show the high fitting ability of the proposed neural network model. Also, the lowest value obtained for the mean squared error is 4.9223x10^(-5) and in epoch 14.

A comprehensive review on the properties of engineered cementitious composite with a self- healing material

The most common types of cementitious materials used as building materials can be found all over the world. The fact remains, however, that deterioration is unavoidable right from the start of the service life, which is followed by maintenance and repair work. Since the cementitious materials have been observed to exhibit a self-healing phenomenon, which has been the subject of research for quite some time. This paper is focused on the review of the feasibility of (Engineered Cementitious Composite) ECC and its properties such as mechanical, physical, rheological, and chemical properties. ECC is considered to have a high self-healing potential and superior mechanical and durability performance. Self-healing concrete is typically employed for the purpose of minimizing cracks in concrete and enhancing the material's overall durability. These mechanisms are reviewed based on extensive experimental studies and practical experience. Self-healing concretes are typically employed for the purpose of mending cracks in concrete and enhancing the material's overall durability. There are many distinct varieties of self-healing processes, including natural, chemical, and biological ones. Studies were conducted with a primary emphasis on biological processes that are dependent on precipitation. In order to study the properties of self-healing with ECC, a transmission electron microscope (TEM), an environmental scanning electron microscope-energy dispersive spectroscopy system (ESEM-EDS), Fourier transform infrared spectroscopy, and X Ray Diffraction (XRD) were all implemented. To further understand the properties of self-healing, this research was conducted. This review offers a fresh perspective on the research done on the topic of treating unexpected cracking in concrete through the use of a self-healing process.

Uncovering the Mechanism of the Role of Fly Ash in the Self-Healing Ability of Mortar with Different Curing Ages.

As an admixture of cement-based materials, the reaction of fly ash (FA) usually takes place in the late age of curing, so FA will affect the self-healing ability of long-age cement-based materials. The self-healing potential and the characteristics of self-healing products of cementitious materials before and after crack healing were analyzed by microscopic tests, and the mechanism of the effect of fly ash on the self-healing performance of cementitious materials was revealed. The results showed that the increase in fly ash content promoted the improvement of the self-repair performance of cracked specimens at 28 d, especially when the fly ash dosage was 40%, the crack opened after 30 d of healing in water was completely closed, the UPV value after recovery was close to 3000 m/s, the self-repair efficiency of maximum amplitude and main frequency amplitude was up to more than 60%, and the recovery rate of compressive strength was increased to more than 30%. However, the increase in fly ash content was not conducive to the self-repair of cracked samples at 210 d, and with the increase in fly ash content, the crack closure effect weakened, the UPV value after recovery decreased, the crack repair rate based on ultrasonic transmission decreased to about 20%, and the compressive strength recovery rate increased slightly. In addition, calcium carbonate precipitation was the main repair product of crack filling and healing, including calcite and spherulite. With the increase in fly ash content, the content of element C in the self-repair products of 28-day-old specimens gradually increased, and the size of calcium carbonate crystals gradually decreased, but the filling was denser, whereas the calcium carbonate crystals in the self-repair products of 210 d specimens gradually became fine and loose.

The Induced Heating–Healing of Inductive Warm-Mix Asphalt Mixture Containing Copper-Slag Filler

Due to environmental pollution and the shortage of nonrenewable natural resources in road construction, the use of copper slag as a new material in asphalt pavement has been recently evaluated for its ability to reduce the accumulation of waste and lower the cost of asphalt mixture production. The main purpose of this study was to assess the feasibility of using copper-slag filler as a substitute for lime in warm-mix asphalt (WMA) to enhance its self-healing and thermal/electrical conductivity potential. To this end, an X-ray fluorescence (XRF) test was first conducted to analyze the copper-slag filler constituent elements that affect its microwave heating. Then, the self-healing potential of asphalt samples containing copper-slag filler under microwave heating was investigated using thermal imaging, and an index was presented to analyze the fracture energy and load-bearing capacity at each stage of the fracture-healing test. Moreover, an image processing technique was used to determine its capability for uniform heat transfer. Finally, some tests were performed to study the asphalt mixture heat-transfer potential and determine its thermal/electrical conductivity. The results show that the mixtures containing copper slag had high thermal/electrical conductivity. Thermal conductivity, microwave heating uniformity, and self-healing potential (asphalt resistance against reloading) of asphalt mixtures increased with an increase in the copper-slag filler content. With 40, 50, and 60 s of microwave heating, the samples containing copper slag had an average of 14%, 31%, and 37% better recovery, respectively, than the asphalt samples containing 100% of lime filler.

Ecological assessment of the soil cover exposed to phosphogypsum dumps

Nowadays, the basis of the production of phosphorous and phosphorous fertilizers in the Republic of Kazakhstan is concentrated at the mineral fertilizers plant of "Kazphosphate" LLP in Zhambyl region. One of the current problems is the study of the negative impact on the ecosystem as a result of the storage of phosphogypsum in the landfills of the mineral fertilizers plant formed during the decomposition of phosphate raw materials, and the study of the self-healing process of an object exposed to anthropogenic impact. The research purpose - ecological assessment of the soil cover exposed in phosphogypsum dumps and the assessment of reclamation potential of this object. The data obtained as a result of the study can be used in the future to monitor objects where fofogypsa residues have accumulated, and for restoration work of damaged soil coverings. During the research were used chemical, geobotanical and landscape-ecological methods. Analysis of the total phosphorus content in soil samples in the study area showed that its toxicity in all objects is not dangerous. It can be seen that the mobile content of zinc and copper in all the obtained soil samples did not exceed the maximum permissible concentration, and the concentration of cadmium in all the obtained points exceeded the maximum permissible concentration and in all other directions except the east increased as it moved away from the center. The self-healing potential of the soil and vegetation cover, conditionally obtained by us, impact-buffer-background zones, respectively, very low-low-satisfactory.

Self-healing master curves of bituminous binders: a non-linear viscoelastic continuum damage framework

In this paper the viscoelastic continuum damage theory was used to investigate the damage and self-healing potential of bituminous binders, considering the effects of rest temperature, thixotropy, and non-linearity. Experimental testing was carried out by using a procedure in which continuous oscillatory shear loading was imparted to the specimens with the inclusion of a single rest period under multiple temperature conditions. Quantification of self-healing included the determination of material integrity gained and damage parameter recovered after the rest period. Such parameters were calculated by excluding time-dependent and non-linear biasing effects, which were directly evaluated by means of a distinct set of experiments. Results were modelled by using the so-called self-healing master curves, constructed by applying the linear viscoelastic time-temperature shift factors. These self-healing master curves are intended to be used as straightforward tools for the prediction of the self-healing response of neat and polymer modified binders in various time-temperature combinations.

A review of the efficiency of self-healing concrete technologies for durable and sustainable concrete under realistic conditions

ABSTRACT Self-healing is recognized as a promising technique for increasing the durability of concrete structures by healing cracks, thereby reducing the need for maintenance activities over the service life and decreasing the environmental impact. Various self-healing technologies have been applied to a wide range of cementitious materials, and the performance has generally been assessed under ‘ideal’ laboratory conditions. Performance tests under ideal conditions, tailored to the self-healing mechanism, can demonstrate the self-healing potential. However, there is an urgent need to prove the robustness and reliability of self-healing under realistic simulated conditions and in real applications before entering the market. This review focuses on the influence of cracks on degradation phenomena in reinforced concrete structures, the efficiency of different healing agents in various realistic (aggressive) scenarios, test methods for evaluating self-healing efficiency, and provides a pathway for integrating self-healing performance into a life-cycle encompassing durability-based design.

Hot mixing: Mechanistic insights into the durability of ancient Roman concrete

Ancient Roman concretes have survived millennia, but mechanistic insights into their durability remain an enigma. Here, we use a multiscale correlative elemental and chemical mapping approach to investigating relict lime clasts, a ubiquitous and conspicuous mineral component associated with ancient Roman mortars. Together, these analyses provide new insights into mortar preparation methodologies and provide evidence that the Romans employed hot mixing, using quicklime in conjunction with, or instead of, slaked lime, to create an environment where high surface area aggregate-scale lime clasts are retained within the mortar matrix. Inspired by these findings, we propose that these macroscopic inclusions might serve as critical sources of reactive calcium for long-term pore and crack-filling or post-pozzolanic reactivity within the cementitious constructs. The subsequent development and testing of modern lime clast-containing cementitious mixtures demonstrate their self-healing potential, thus paving the way for the development of more durable, resilient, and sustainable concrete formulations.

Properties and improvement of ultra-high performance concrete with coarse aggregates and polypropylene fibers after high-temperature damage

Ultra-high performance concrete containing coarse aggregates (UHPC-CA) is more cost-effective, with its low cost and easy access to materials, but its high-temperature performance and self-healing capability after post-fire curing remain to be further explored. In this paper, after high temperature, the compressive strength increases by approximately 20 MPa within 400 °C, and the micro-characteristics reveal that this is mainly because the temperature promotes the cement hydration reaction and pozzolanic reaction, which plays the role of secondary accelerated curing. Due to the continuous decomposition of substances, the flexural strength and ultrasonic pulse velocity gradually decrease; the mass loss, total porosity, and the amount of absorbed water increase, especially the sorptivity coefficient, which increases by more than 100 times after 800 °C. The residual values of all properties of UHPC-CA are best maintained by adding all of the finer PP fibers. Relying on many unhydrated gelling materials, UHPC has a more significant self-healing potential, improving its mechanical properties and permeability in all three post-fire curing environments. The most significant effect is seen in the water environment, where its recovery rate of strength exceeds 50 % in all cases. The self-healing enhancement of UHPC does not come from a single source, but from multiple combinations of physical and chemical reaction processes.

Insight into the temperature stimulation on the self-healing properties of cement-based materials

The concrete constructions under the complex and variable external loads easily produce structural cracks, severely limiting the service life. Traditional methods for crack repairing such as spraying and chemical grouting, are usually with the high cost and potential environmental problems. In recent years, microbial self-healing has aroused great attention in the crack repair of concrete due to its environmental safety and high self-healing potential. Nevertheless, previous studies have shown that the healing efficiency of microbial cement stones at low temperatures was not ideal. Temperature stimulation seems to be feasible to accelerate the healing process because temperature is one of the critical factors impacting microbial mineralization. To verify the applicability of temperature stimulation to the regulation of microbial healing efficiency, this paper investigated the changes in growth rate, urease activity, cell shape, and mineralization rate of Sporosarcina pasteurii under temperature stimulation at first. And then, the healing properties of cement stones without cracking and cracked cement stones under temperature stimulation were evaluated. The interaction mechanism of temperature stimulation on the healing properties was revealed by establishing the relationship between the microstructure parameters and macro performance. This paper proved that it was capable to improve the healing efficiency of microbial cement stones by temperature stimulation. Besides, the results showed that at 7 ∼ 37 °C, the growth rate and mineralization rate of bacteria were improved by raising the culturing temperature. Moreover, we found that temperature stimulation impacted the growth and the mineralization of bacteria, thus, influencing the microstructure and healing properties of microbial cement stones. In addition, the healing efficiency was dominated by microbial mineralization rather than cement hydration at 7 ∼ 43 °C. More importantly, the temperature stimulation on the microbial cement stones with Sporosarcina pasteurii should be limited within 43 °C. This paper provides a reference for the research on the improvement of the healing efficiency in microbial cement materials with temperature stimulation.

Evaluation of self-healing in cementitious materials with superabsorbent polymers through ultrasonic mapping

The maintenance and repair of concrete infrastructure covers an increasing portion of the annual construction budget. For this reason, self-healing cementitious materials have been investigated thoroughly in literature. One way to achieve an effective self-healing composite is by promoting their inherent repair ability through the inclusion of superabsorbent polymers (SAPs). Thanks to their large absorption capacity upon contact with water, SAPs allow to preserve the humidity inside the cracks for a longer period of time, which is essential to promote the autogenous healing process. In order to encourage the application of SAPs for self-healing purposes, adequate assessment techniques should be at hand in order to evaluate a SAP’s effectiveness for self-repair. Whereas various methods, such as water permeability tests and microscopic analysis, are used to assess a material’s self-healing potential, mechanical tests are needed to determine the regain in mechanical performance. Due to the destructive nature of these methods, the monitoring of the self-healing mechanism over time is practically impossible. In the present research, a non-destructive testing methodology based on ultrasonic wave through transmission was investigated, due to its sensitivity to the elastic properties of the material under study. By means of ultrasonic mapping, the interior was visualized and allowed to determine the degree and uniformity of healing along the depth for different healing times for the first time in literature.

Individualized Assessment and Therapeutic Intervention for Mental Health of American Postmodern Novelists.

Objective Therapeutic intervention can improve the overall level of mental health of American postmodern fiction writers by improving their social communication skills and overall well-being. This paper discusses the application of art therapy in the mental health education of American postmodern novel creators and proves that expressive art therapy intervention is effective in improving the mental health level of American postmodern novel creators. Method This article attempts to help American postmodernist novel creators understand their own mental health status by means of individualized assessment and therapeutic intervention and to analyze and discover their own potential mental health problems. The writers of postmodernist novels in the USA were measured and screened by means of scales and questionnaires, and the members who met the experimental intervention were divided into experimental group and control group, and the experimental group received a 30-day reception music therapy intervention. After the intervention, the data will be counted, and the quantitative and qualitative aspects will be analyzed to comprehensively evaluate the effect of the intervention. Results/Discussion. Receptive music therapy intervention has a significant effect in relieving the anxiety of American postmodernist novel creators and plays a positive role in helping American postmodernist novel creators better adapt to study life and build good emotional psychology and interpersonal relationships. Psychological counseling relies more on external forces to correct cognition and adjust psychology, while music therapy intervention, as a nonsemantic art, can arouse inner functions and mobilize the self-healing potential of American postmodern novel creators. Practice has proven that when the language intervention of traditional psychotherapy encounters resistance and silence, music as a special language plays a vital role. The nonlinguistic nature of music, through a mode of reproduction of sounds in nature, makes the beautiful and soothing melody stimulate a pleasant and peaceful psychological experience through human hearing.

Self-Healing Potential of Porous Asphalt Concrete Containing Different Aggregates and Metal Wastes Through Microwave Heating

Asphalt is known as a self-healing material due to its temperature-related flow behavior. When damage occurs in asphalt concrete, bitumen can flow into cracks with heat and provide recovering by filling the cracks. Much of the current literature on self-healing pays particular attention to artificially heat asphalt concrete by several methods, including microwave heating. Although there is a growing body of literature that recognizes using steel fibers in microwave healing asphalt, there are no data on the use of aluminum fibers to improve microwave healing. This paper evaluates the microwave healing potential of asphalt concrete that contains metal wastes such as aluminum and steel shavings. Besides, the use of basalt and limestone aggregate (BA and LA) in asphalt concrete were evaluated. To achieve this, firstly, microwave absorption capabilities of BA and LA were determined. In the second step of the study, porous asphalt concrete specimens were prepared, and they were damaged by the indirect tensile (IDT) strength test at low temperatures. After that, damaged specimens were healed via microwave heating, and they were damaged again by the IDT strength test. In the end, the healing index of the specimens was determined as the proportion of healed specimen’s strength to the original. It has been found that BA is almost three times more microwave absorber material than LA, and asphalt specimens containing BA showed better healing performance. It has also been demonstrated for the first time that aluminum shavings might be a better option than steel shavings to accelerate microwave healing.