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1
Luhar, Salmabanu, Ismail Luhar, and Faiz Uddin Ahmed Shaikh. "Review on Performance Evaluation of Autonomous Healing of Geopolymer Composites." Infrastructures 6, no. 7 (2021): 94. http://dx.doi.org/10.3390/infrastructures6070094.
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It is a universal fact that concrete is one of the most employed construction materials and hence its exigency is booming at a rocket pace, which in turn, has resulted in a titanic demand of ordinary Portland cement. Regrettably, the production of this essential binder of concrete is not merely found to consume restricted natural resources but also found to be associated with emission of carbon dioxide—a primary greenhouse gas (GHG) which is directly answerable to earth heating, resulting in the gigantic dilemma of global warming. Nowadays, in order to address all these impasses, researchers are attracted to innovative Geopolymer concrete technology. However, crack development of various sizes within the concrete is inevitable irrespective of its kind, mix design, etc., owing to external and internal factors viz., over-loading, exposure to severe environments, shrinkage, or error in design, etc., which need to be sealed otherwise these openings permits CO2, water, fluids, chemicals, harmful gases, etc., to pass through reducing service life and ultimately causing the failure of concrete structures in the long term. That is why instant repairs of these cracks are essential, but manual mends are time-consuming and costly too. Hence, self-healing of cracks is desirable to ease their maintenances and repairs. Self-healing geopolymer concrete (SHGPC) is a revolutionary product extending the solution to all these predicaments. The present manuscript investigates the self-healing ability of geopolymer paste, geopolymer mortar, and geopolymer concrete—a slag-based fiber-reinforced and a variety of other composites that endow with multifunction have also been compared, keeping the constant ratio of water to the binder. Additionally, the feasibility of bacteria in a metakaolin-based geopolymer concrete for self-healing the cracks employing Bacteria-Sporosarcina pasteurii, producing Microbial Carbonate Precipitations (MCP), was taken into account with leakage and the healing process in a precipitation medium. Several self-healing mechanisms, assistances, applications, and challenges of every strategy are accentuated, compared with their impacts as a practicable solution of autogenously-healing mechanisms while active concretes are subjected to deterioration, corrosion, cracking, and degradation have also been reviewed systematically.
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Shen, Li’an, Wenlu Yu, Lin Li, et al. "Microorganism, Carriers, and Immobilization Methods of the Microbial Self-Healing Cement-Based Composites: A Review." Materials 14, no. 17 (2021): 5116. http://dx.doi.org/10.3390/ma14175116.
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Low tensile strength, poor elastic modulus, and complex concrete cracking work condition are almost unavoidable due to the intrinsic brittleness. To deal with concrete maintenance and durability, microbial self-healing concretes have been rapidly developed and widely applied recently. The microbial self-healing can specifically patch fractures as well as boost the concrete structure’s capacity, durability, and permeability. This paper presents the state-of-the-art in the microbe induced self-healing in cement-based composites. The microorganism and carriers were classified according to the working theory and repair effects. Additionally, the precise efficiency and effect of various technologies are also evaluated for microbial immobilization. Based on the literature review and summary from the perspective of microorganism, carriers, and immobilization methods, challenges and further works are discussed.
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An, Seongpil, Sam S. Yoon, and Min Wook Lee. "Self-Healing Structural Materials." Polymers 13, no. 14 (2021): 2297. http://dx.doi.org/10.3390/polym13142297.
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Self-healing materials have been developed since the 1990s and are currently used in various applications. Their performance in extreme environments and their mechanical properties have become a topic of research interest. Herein, we discuss cutting-edge self-healing technologies for hard materials and their expected healing processes. The progress that has been made, including advances in and applications of novel self-healing fiber-reinforced plastic composites, concrete, and metal materials is summarized. This perspective focuses on research at the frontier of self-healing structural materials.
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Jiang, Shiping, Zhiyang Lin, Can Tang, and Wenfeng Hao. "Preparation and Mechanical Properties of Microcapsule-Based Self-Healing Cementitious Composites." Materials 14, no. 17 (2021): 4866. http://dx.doi.org/10.3390/ma14174866.
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Self-healing concrete designs can protect against deterioration and improve durability. However, there is no unified conclusion regarding the effective preparation and mechanical properties of self-healing concrete. In this paper, microcapsules are used in cement-based materials, the reasonable dosage of microcapsules is determined, and the self-healing performance of the microcapsule self-healing system under different curing agents is explored. The microcapsules and curing agent are shown to enhance the flexural and compressive strength of mortar specimens at relatively low contents. The optimal microcapsule content in terms of compressive strength is 1–3%. When the content of the microcapsule reaches 7%, the strength of the specimen decreases by approximately 30%. Sodium fluorosilicate is better-suited to the microcapsule self-healing cement-based system than the other two fluorosilicates, potassium fluorosilicate and magnesium, which have similarly poor healing performance as curing agents. Healing time also appears to significantly influence the microcapsule self-healing system; mortar specimens that healed for 28 days are significantly higher than those that healed for 7 days. This work may provide a valuable reference for the design and preparation of self-healing cementitious composite structures.
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Choi, Se-Jin, Ji-Hwan Kim, Hyojin Jeong, et al. "Simulated and Experimental Investigation of the Mechanical Properties and Solubility of 3D-Printed Capsules for Self-Healing Cement Composites." Materials 14, no. 16 (2021): 4578. http://dx.doi.org/10.3390/ma14164578.
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In the concrete industry, various R&D efforts have been devoted to self-healing technology, which can maintain the long-term performance of concrete structures, which is important in terms of sustainable development. Cracks in cement composites occur and propagate because of various internal and external factors, reducing the composite’s stability. Interest in “self-healing” materials that can repair cracks has led researchers to embed self-healing capsules in cement composites. Overcoming the limitations of polymer capsules produced by chemical manufacturing methods, three-dimensional (3D) printing can produce capsules quickly and accurately and offers advantages such as high material strength, low cost, and the ability to fabricate capsules with complex geometries. We performed structural analysis simulations, experimentally evaluated the mechanical properties and solubility of poly(lactic acid) (PLA) capsules, and examined the effect of the capsule wall thickness and printing direction on cement composites embedded with these capsules. Thicker capsules withstood larger bursting loads, and the capsule rupture characteristics varied with the printing angle. Thus, the capsule design parameters must be optimized for different environments. Although the embedded capsules slightly reduced the compressive strength of the cement composites, the benefit of the encapsulated self-healing agent is expected to overcome this disadvantage.
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Negrini, Alberto, Marta Roig-Flores, Eduardo J. Mezquida-Alcaraz, Liberato Ferrara, and Pedro Serna. "Effect of crack pattern on the self-healing capability in traditional, HPC and UHPFRC concretes measured by water and chloride permeability." MATEC Web of Conferences 289 (2019): 01006. http://dx.doi.org/10.1051/matecconf/201928901006.
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Concrete has a natural self-healing capability to seal small cracks, named autogenous healing, which is mainly produced by continuing hydration and carbonation. This capability is very limited and is activated only when in direct contact with water. High Performance Fibre-Reinforced Concrete and Engineered Cementitious Composites have been reported to heal cracks for low damage levels, due to their crack pattern with multiple cracks and high cement contents. While their superior self-healing behaviour compared to traditional concrete types is frequently assumed, this study aims to have a direct comparison to move a step forward in durability quantification. Reinforced concrete beams made of traditional, high-performance and ultra-high-performance fibre-reinforced concretes were prepared, sized 150×100×750 mm3. These beams were pre-cracked in flexion up to fixed strain levels in the tensioned zone to allow the analysis of the effect of the different cracking patterns on the self-healing capability. Afterwards, water permeability tests were performed before and after healing under water immersion. A modification of the water permeability test was also explored using chlorides to evaluate the potential protection of this healing in chloride-rich environments. The results show the superior durability and self-healing performance of UHPFRC elements.
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Toader, Tudor Panfil, and Anamaria Cătălina Mircea. "Self-Healing Concrete Mix-Design Based on Engineered Cementitious Composites Principles." Proceedings 63, no. 1 (2020): 5. http://dx.doi.org/10.3390/proceedings2020063005.
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Concrete is the most used material in the construction industry, being prone to cracking. Following the action of aggressive external agents, through cracks, access routes to the embedded reinforcement are created. By enclosing in concrete various materials that can induce the self-healing property, by taking actions when the cracks appear, the access of the external aggressive agents to the reinforcement can be stopped, therefore creating more durable materials. The aim of the research is to design a micro concrete with self-healing properties, based on Engineered Cementitious Composites principles from the literature and using local raw materials.
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Zhang, Wei, Qiaofeng Zheng, Ashraf Ashour, and Baoguo Han. "Self-healing cement concrete composites for resilient infrastructures: A review." Composites Part B: Engineering 189 (May 2020): 107892. http://dx.doi.org/10.1016/j.compositesb.2020.107892.
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Sadam Hussain Jakhrani, Jae-Suk Ryou, Hong-Gi Kim, In Kyu Jeon, Abdul Qudoos, and tta-ur-Rehman. "Review on the self-healing concrete-approach and evaluation techniques." Journal of Ceramic Processing Research 20, no. ll (2019): 1–18. http://dx.doi.org/10.36410/jcpr.2019.20..1.
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Geraldo, R. H., A. M. Guadagnini, and G. Camarini. "Self-healing concrete with crystalline admixture made with different cement content." Cerâmica 67, no. 383 (2021): 370–77. http://dx.doi.org/10.1590/0366-69132021673833118.
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Yoo, Kyung Suk, Seung Yup Jang, and Kwang-Myong Lee. "Recovery of Chloride Penetration Resistance of Cement-Based Composites Due to Self-Healing of Cracks." Materials 14, no. 10 (2021): 2501. http://dx.doi.org/10.3390/ma14102501.
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This study proposed a method of applying coating on uncracked surfaces of test specimens in the electrical migration–diffusion test for the evaluation of the chloride penetration resistance of cracked cement-based composites. It was shown that, by applying the proposed method, the recovery of the chloride penetration resistance from self-healing of cracks can be evaluated more accurately because the application of surface coating reduces the test time and the error introduced by over-simplification. Based on observations of the self-healing-induced recovery of chloride penetration resistance, a phenomenological model for predicting the progress of crack self-healing in cement-based composites was suggested. This model is expected to evaluate the chloride penetration resistance more accurately in actual concrete structures with cracks.
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Mircea, A. C., and T. P. Toader. "Designing Concrete with Self-healing Properties Using Engineered Cementitious Composites as a Model." IOP Conference Series: Materials Science and Engineering 877 (July 18, 2020): 012035. http://dx.doi.org/10.1088/1757-899x/877/1/012035.
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Choi, Heesup, Masumi Inoue, Sukmin Kwon, Hyeonggil Choi, and Myungkwan Lim. "Effective Crack Control of Concrete by Self-Healing of Cementitious Composites Using Synthetic Fiber." Materials 9, no. 4 (2016): 248. http://dx.doi.org/10.3390/ma9040248.
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Wu, Shuyin, Guoyang Lu, Quan Liu, Pengfei Liu, and Jun Yang. "Sustainable High-Ductility Concrete with Rapid Self-Healing Characteristic by Adding Magnesium Oxide and Superabsorbent Polymer." Advances in Materials Science and Engineering 2020 (January 22, 2020): 1–12. http://dx.doi.org/10.1155/2020/5395602.
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As a class of high-ductility concrete, engineered cementitious composites (ECC) have wide application prospects in engineering fields. However, the occurrence of cracks and the limited self-healing ability hinder the development of ECC. Rapid self-healing has important significance for ECC in reducing maintenance costs and prolonging service life, which are conducive to sustainable development of ECC. Therefore, the aim of this paper is to enhance the self-healing property of ECC by adding light-burned magnesium oxide (MgO) and superabsorbent polymer (SAP) on the premise of maintaining the high ductility. First, the effect of MgO and SAP on the ductility property of ECC which is the most important feature was explored with the uniaxial tensile test. The results indicated that MgO is helpful to the strength but not conducive to the ductility of ECC, while SAP has an opposite effect. The effects of MgO and SAP on the ductility of ECC can be balanced. Later, the permeability test, scanning electron microscopy (SEM), and X-ray diffraction (XRD) were used to evaluate the effects of MgO and SAP on the self-healing property of ECC. The results showed that the combined addition of MgO and SAP shows much better effect than the individual addition and can cut the healing time by half. Overall, it is concluded that ECC with MgO and SAP have the potential for self-healing, and the ductility can also be reconciled.
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Lee, Kwang-Myong, Young-Cheol Choi, Byoungsun Park, Jinkyo Choo, and Sung-Won Yoo. "Effect of Clinker Binder and Aggregates on Autogenous Healing in Post-Crack Flexural Behavior of Concrete Members." Materials 13, no. 20 (2020): 4516. http://dx.doi.org/10.3390/ma13204516.
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Crack healing has been studied extensively to protect reinforced concrete structures from the ingress of harmful ions. Research examining the regain in the mechanical properties of self-healing composites has focused mostly on the computation of the healing ratio based on the measurement of the tensile and compressive strengths but with poor regard for the flexural performance. However, the regain in the flexural performance should also be investigated for design purposes. The present study performs flexural testing on reinforced concrete members using crushed clinker binder and aggregates as well as crystalline admixtures as healing agents. Healing ratios of 100% for crack widths smaller than 200 μm and 85% to 90% for crack widths of 250 μm were observed according to the admixing of clinker binder and aggregates. Water flow test showed that the members replacing binder by 100% of clinker achieved the best crack healing performance. The crack healing property of concrete improved to some extent the rebar yield load, the members’ ultimate load and energy absorption capacity and ductility index. The crack distribution density from the observed crack patterns confirmed the crack healing effect provided by clinker powder. The fine grain size of clinker made it possible to replace fine aggregates and longer healing time increased the crack healing effect.
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Hee Seok Lee and Kwang Ho Sho. "Feasibility study of inorganic anti-corrosion agents with self-healing capabilities for reinforced concrete structures." Journal of Ceramic Processing Research 20, no. ll (2019): 100–108. http://dx.doi.org/10.36410/jcpr.2019.20..100.
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Mauludin, Luthfi M., Xiaoying Zhuang, and Timon Rabczuk. "Computational modeling of fracture in encapsulation-based self-healing concrete using cohesive elements." Composite Structures 196 (July 2018): 63–75. http://dx.doi.org/10.1016/j.compstruct.2018.04.066.
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Algaifi, Hassan Amer, Suhaimi Abu Bakar, Rayed Alyousef, et al. "Bio-inspired self-healing of concrete cracks using new B. pseudomycoides species." Journal of Materials Research and Technology 12 (May 2021): 967–81. http://dx.doi.org/10.1016/j.jmrt.2021.03.037.
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Hanxing He, Jiantao Zhang, Jinlong Zhang, et al. "Efficiency of gerAa, tupA and ca transformation in Bacillus subtilis for self-healing of concrete cracks." Journal of Ceramic Processing Research 20, no. 5 (2019): 470–78. http://dx.doi.org/10.36410/jcpr.2019.20.5.470.
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Khitab, Anwar. "Nano Wonders in Concrete Technology: Mini Review." Journal of Cement Based Composites 1, no. 1 (2020): 25–28. http://dx.doi.org/10.36937/cebacom.2020.001.005.
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Concrete is one of the most significant materials, man has produced. Conventionally, it is a mixture of cement, sand, coarse aggregates and water. It is versatile, and gains strength in a few weeks after its casting. It can withstand extreme weather conditions. However, traditional concrete also has some drawbacks. It has low tensile strength and develops cracks, which limit its usefulness. The performance of concrete can be enhanced by carefully selecting its ingredients and employing appropriate modern techniques. One such technique is the use of nano particles. Nano particles, due to their small size, possess very high surface area to volume ratio. They can be used as inert filler as well as chemically active ingredients in cementitious composites. Being filler, they can fill up very small voids in the matrix. As active ingredients, they can result in higher chemical reactivity. This work focuses on the wonders, nano particles have brought in concrete technology. The topics include self-healing, de-pollutant, de-icing and energy-saving concrete materials.
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Tomczak, Kamil, Jacek Jakubowski, and Przemysław Fiołek. "Method for Assessment of Changes in the Width of Cracks in Cement Composites with Use of Computer Image Processing and Analysis." Studia Geotechnica et Mechanica 39, no. 2 (2017): 73–80. http://dx.doi.org/10.1515/sgem-2017-0017.
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Abstract Crack width measurement is an important element of research on the progress of self-healing cement composites. Due to the nature of this research, the method of measuring the width of cracks and their changes over time must meet specific requirements. The article presents a novel method of measuring crack width based on images from a scanner with an optical resolution of 6400 dpi, subject to initial image processing in the ImageJ development environment and further processing and analysis of results. After registering a series of images of the cracks at different times using SIFT conversion (Scale-Invariant Feature Transform), a dense network of line segments is created in all images, intersecting the cracks perpendicular to the local axes. Along these line segments, brightness profiles are extracted, which are the basis for determination of crack width. The distribution and rotation of the line of intersection in a regular layout, automation of transformations, management of images and profiles of brightness, and data analysis to determine the width of cracks and their changes over time are made automatically by own code in the ImageJ and VBA environment. The article describes the method, tests on its properties, sources of measurement uncertainty. It also presents an example of application of the method in research on autogenous self-healing of concrete, specifically the ability to reduce a sample crack width and its full closure within 28 days of the self-healing process.
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Song, Jun, Fuyan Chen, and Guangxiu Guo. "Research on Self-Healing Technology of SBS Modified Asphalt Concrete under the Dynamic Loading." Integrated Ferroelectrics 207, no. 1 (2020): 12–26. http://dx.doi.org/10.1080/10584587.2020.1728661.
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Lim, Taeuk, Hao Cheng, Wonil Song, Jasung Lee, Sunghoon Kim, and Wonsuk Jung. "Simulated and Experimental Investigation of Mechanical Properties for Improving Isotropic Fracture Strength of 3D-Printed Capsules." Materials 14, no. 16 (2021): 4677. http://dx.doi.org/10.3390/ma14164677.
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Three-dimensional (3D) printer-based self-healing capsules, embedded in cement composites, were proposed to heal cracks, as they allow for various structural designs of capsules, repeatable fabrication, and strength analysis. Out of many 3D printing methods, such as fusion deposition modeling (FDM), powder layer fusion, and PolyJet printing, FDM was used to design, analyze, and produce new self-healing capsules, which are widely used due to their high-speed, low-cost, and precise manufacturing. However, the PLA extruded in the FDM had low adhesion energy between stacked layers, which caused a degradation of the performance of the self-healing capsule, because it had different strengths depending on the angle between the stacked layers and the applied load within the concrete structure. Therefore, in this paper, specimens were produced, in accordance with ASTM specifications, using the FDM PLA method, and mechanical properties were obtained through tensile, shear, and compression tests. Additionally, the isotropic fracture characteristics of the four types of capsules were analyzed through finite element method analysis. Subsequently, the 3D-printed capsules were produced, and the fracture strength was analyzed in the x, y and z directions of the applied load through a compression test. As a result, the newly proposed capsule design was verified to have an isotropic fracture strength value of 1400% in all directions compared to conventional spherical thin film capsules
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Wittmann, Folker H., Penggang Wang, Peng Zhang, and Tiejun Zhao. "Capillary Absorption and Chloride Penetration into High-Performance Fiber-Reinforced Cement-Based Composites (HPFRCC) as Influenced by Tensile Stress and Self-Healing." Restoration of Buildings and Monuments 21, no. 2-3 (2015): 75–80. http://dx.doi.org/10.1515/rbm-2015-0009.
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Abstract High-performance fiber-reinforced cement-based composites (HPFRCC) can be characterized by low porosity and fine pores as compared to normal concrete and therefore this interesting material absorbs little water or aqueous salt solutions if exposed to aggressive environment. These properties are indications for excellent durability and long service life of structural members or structures made with this high-performance material. In practice, however, most structures and structural elements are designed to be load bearing. The influence of an applied tensile stress on capillary absorption was investigated and results are presented in this contribution. It was found that the coefficient of capillary absorption increases rapidly if a tensile stress exceeding half of the tensile strength is applied. This observation has to be taken into consideration if HPFRCC is to be applied in aggressive environment. The maximum admissible stress must be reduced accordingly.
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Li, Siqi, Yecheng Feng, and Jinbo Yang. "Expansion Mechanism and Properties of Magnesium Oxide Expansive Hydraulic Cement for Engineering Applications." Advances in Materials Science and Engineering 2021 (May 5, 2021): 1–9. http://dx.doi.org/10.1155/2021/5542072.
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The expansion mechanism of magnesium oxide expansive hydraulic cement as a novel expansive hydraulic cement was reviewed. Anisotropic crystallization results in crystal growth pressure, causing volume expansion while also increasing the porosity of the whole system. The theoretical relationship between porosity and expansion was analyzed. A basic method is given for predicting the expansion rate considering the expansive agent content in MgO expansive hydraulic cement. A concise equation is proposed for calculating the ultimate expansion. A theoretical relationship between porosity and expansion is presented. The compressive strength and durability of magnesium oxide expansive hydraulic cement were analyzed considering porosity changes and compared with hydraulic cement. If the expansion rate exceeds 0.8%, the mechanical properties and durability changes caused by porosity should be considered. If magnesium oxide expansive concrete is used with restraining in real structure, extra compressive stress is generated and the porosity decreases, compared with that during free expansion. In particular, for strain-hardening cementitious composites, expansion confined with the fibers present in the composite is beneficial for refining cracks and improving the self-healing ability of these materials whenever exposed to humid environments. This paper describes the expansion mechanism and properties of magnesium oxide expansive hydraulic cement for engineering applications.
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Guo, Li-Ping, Li-Juan Chai, Yan-Hui Xu, Cong Ding, and Yuan-Zhang Cao. "Corrosion behavior of steel bar embedded in high-ductility cementitious composites under the coupled action of dry–wet cycles and chloride attack." Anti-Corrosion Methods and Materials 68, no. 3 (2021): 209–18. http://dx.doi.org/10.1108/acmm-07-2020-2346.
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Purpose High-ductility cementitious composites (HDCC) have an excellent crack controlled capacity and corrosion resistance capacity, which has a promising application in structure engineering under harsh environment. The purpose of this study is to explore the corrosion mechanism of steel bar in HDCC. Design/methodology/approach Intact and the pre-cracked HDCC specimens under the coupled action of different dry–wet cycles and chloride attack were designed, and intact normal concrete (NC) was also considered for comparison. Corrosion behavior of a steel bar embedded in HDCC was analyzed by an electrochemical method, a chloride permeability test and X-ray computed tomography. Findings Steel corrosion probability is related to the chloride permeability of the HDCC cover, and the chloride permeability resistance of HDCC is better than that of NC. Besides, crack is the key factor affecting the corrosion of steel bars, and the HDCC with narrower cracks have a lower corrosion rate. Slight pitting occurs at the crack tips. In addition, the self-healing products and corrosion products fill up the cracks in HDCC, preventing the external aggressive ions from entering and thereby decreasing the steel corrosion rate. Originality/value HDCC has a superior corrosion resistance than that of NC, effects of variable crack width on corrosion behavior of steel bar in HDCC under the coupled actions of different dry–wet cycles and chloride attack are investigated, which can provide the guide for the design application of HDCC material in structure engineering exposed to marine environment.
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DONG, BIQIN, NINGXU HAN, MING ZHANG, XIANFENG WANG, HONGZHI CUI, and FENG XING. "A MICROCAPSULE TECHNOLOGY BASED SELF-HEALING SYSTEM FOR CONCRETE STRUCTURES." Journal of Earthquake and Tsunami 07, no. 03 (2013): 1350014. http://dx.doi.org/10.1142/s1793431113500140.
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In the study, a novel microcapsule technology based self-healing system for concrete structures has been developed. Through situ-polymerization reaction, the microcapsule is formed by urea formaldehyde resin to pack the epoxy material, which is applied to cementitious composite to achieve self-healing effect. The experimental results revealed that the self-healing efficiency of the composite can be accessed from the recovery of the permeability and strength for the cracked cementitious specimens as the healing agent in the microcapsule acting on the cracks directly. Scanning electronic microscope (SEM/EDX) results show that the epoxy resin is released along with the cracking of the cementitious composite and prevent from cracks continued growth. Further studies show that the self-healing efficiency is affected by the pre-loading of composite, particle size of microcapsule, aging duration of healing agent and so on.
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Zhang, Ming, Feng Xing, Kai Yong Shi, and Xue Xiao Du. "Study on Organic Microcapsule Based Self-Healing Cementitious Composite." Advanced Materials Research 239-242 (May 2011): 764–67. http://dx.doi.org/10.4028/www.scientific.net/amr.239-242.764.
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Base on engineering application need, the subject introduce microcapsule that contains adhesive into cementituous composite for realizing the self-healing characteristics of cracked concrete. The technique has good industry feasibility, process operability, and reproducibility of self-healing characteristic. It is can resolve partial problems that other current self-healing methods are facing.
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Zhou, Shuai, Hehua Zhu, J. Woody Ju, Zhiguo Yan, and Qing Chen. "Modeling microcapsule-enabled self-healing cementitious composite materials using discrete element method." International Journal of Damage Mechanics 26, no. 2 (2017): 340–57. http://dx.doi.org/10.1177/1056789516688835.
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Concrete with a micro-encapsulated healing agent is appealing due to its self-healing capacity. The discrete element method (DEM) is emerging as an increasingly used approach for investigating the damage phenomenon of materials at the microscale. It provides a promising way to study the microcapsule-enabled self-healing concrete. Based on the experimental observation and DEM, a three-dimensional damage-healing numerical model of microcapsule-enabled self-healing cementitious materials under compressive loading is proposed. The local healing effect can be simulated in our model, as well as the stress concentration effect and the partial healing effect. The healing variable of the DEM model is developed to describe the healing process. We examine the dependence of the mechanical properties of the microcapsule-enabled self-healing material on (a) the stiffness of the solidified healing agent, (b) the strength of the solidified healing agent, (c) the initial damage of specimens, and (d) the partial healing effect. In particular, the proposed numerical damage-healing model demonstrates the potential capability to explain and simulate the physical behavior of microcapsule-enabled self-healing materials on the microscale.
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Litina, Chrysoula, and Abir Al-Tabbaa. "Development of sustainable concrete repair materials via microencapsulated agents." MATEC Web of Conferences 289 (2019): 11002. http://dx.doi.org/10.1051/matecconf/201928911002.
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Identification of non-structural damage in concrete infrastructure and actuation of preventive repair solutions is an established approach to avoid further structural damages and more expensive repair regimes. However the repair of concrete itself is not infallible with 55% of reported repairs in the EU failing within 5 years of service. Thus the already once repaired concrete structure is then subject to a constant cycle of repeated repair and a cumulative associated life cycle cost. The development of external repair material with self-healing capabilities, can affect a real step-change on the life-cycle costs and maintenance of existing and new infrastructure. Developed polymeric microcapsules containing liquid sodium silicate were used to impart autonomic self-healing to readily available commercial repair mortars for the first time. These materials cover a range of potential real time repair applications. Initially the compatibility between the developed self-healing agents and commercial products was established and the self-healing performance of the novel composite system was then evaluated. The results underlined the huge potential for the proposed composite systems as a stepping stone toward commercial uptake of self-healing microcapsule-based cementititious materials.
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Zhang, Zhigang, Shunzhi Qian, Hezhi Liu, and Victor C. Li. "Ductile Concrete Material with Self-Healing Capacity for Jointless Concrete Pavement Use." Transportation Research Record: Journal of the Transportation Research Board 2640, no. 1 (2017): 78–83. http://dx.doi.org/10.3141/2640-09.
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The existence of joints in concrete pavement tends to cause many distresses and driving discomfort, thus resulting in high maintenance and shortened service life. This study achieved jointless function in concrete pavement by utilizing the high ductility and self-healing capacity of engineered cementitious composite (ECC). From the preliminary experimental results, ECC showed high strain capacity of 4.4% and deflection capacity of 7.9 mm under tension and bending, overcoming the brittleness of normal concrete. The flexural and compressive strengths of ECC are 12.2 and 45.8 MPa, respectively, which could meet the requirements of heavy-duty concrete pavement in accordance with design guidance in China. Under restrained shrinkage, ECC also shows a very low tendency to form fracture failure. In addition, the self-healing phenomenon is observed in ECC. Its stiffness, tensile strain capacity, tensile strength, and resonant frequency value show a very high recovery level after self-healing, nearly approaching that of virgin ECC of the same age. The water permeability coefficient of predamaged ECC decreases gradually with self-healing age, and eventually is close to that of the undamaged specimens. Based on the experimental results, it is concluded that ECC material, as expected, has the potential to be used in jointless concrete pavement.
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Chen, Qing, Zhengwu Jiang, Hehua Zhu, et al. "A multiphase micromechanical model for unsaturated concrete repaired by electrochemical deposition method with the bonding effects." International Journal of Damage Mechanics 27, no. 9 (2018): 1307–24. http://dx.doi.org/10.1177/1056789518773633.
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Most concrete structures repaired by the electrochemical deposition method are not fully saturated and the healing interfaces are not always perfect in reality. To demonstrate these issues, micromechanical models are presented for unsaturated concrete repaired by electrochemical deposition method with the healing interfacial transition zone based on our latest work. The repaired unsaturated concrete is represented as a multiphase composite made up of the water, unsaturated pores, intrinsic concrete, deposition products and the healing interfacial transition zone between the latter two components. The equivalent particle, matrix and composite for repaired unsaturated concrete are obtained by modifying the differential-scheme and the generalized self-consistent method. Modifications are utilized to rationalize the differential-scheme based estimations by taking into the water (including further hydration and viscosity effects), interfacial transition zone and the shapes of the pores into considerations. Furthermore, our predictions are compared with those of the existing models and available experimental results, thus illustrating the feasibility and capability of the proposed micromechanical framework.
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Jefferson, Anthony, Tharmesh Selvarajoo, Brubeck Freeman, and Robert Davies. "An experimental and numerical study on vascular self-healing cementitious materials." MATEC Web of Conferences 289 (2019): 01004. http://dx.doi.org/10.1051/matecconf/201928901004.
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This paper gives an overview of a combined experimental-numerical study on vascular self-healing (SH) systems for cementitious composite materials. The work aimed to bridge the gap between numerical and experimental investigations for this type of SH system and to provide a set of data for developing, calibrating and validating a finite element model for these materials. The study investigated both healing-agent transport and mechanical damage-healing processes, including healing-agent curing. The experimental programme included mechanical tests on notched concrete beams and compact direct-tension specimens with inbuilt vascular healing systems, as well as tests to measure the transport properties of healing-agent within discrete concrete cracks and through the concrete matrix. The new coupled model employs elements with embedded strong discontinuities to simulate cracks and mechanical healing behaviour. A damage-healing constitutive model is described that simulates multiple damage-healing ‘events’. This mechanical model is coupled to discrete and continuum flow models that simulate healing-agent transport. The transport model accounts for pressurised and capillary flow, as well as curing-dependent flow properties. The main focus of this contribution is to show how these parallel programmes of work were combined so that the experimental observations guided the numerical developments and modelling questions were answered using experimental findings.
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Choi, Inoue, Kim, Choi, and Sengoku. "Effect of Addition of Ca2+ and CO32− Ions with Temperature Control on Self-Healing of Hardened Cement Paste." Materials 12, no. 15 (2019): 2456. http://dx.doi.org/10.3390/ma12152456.
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: Concrete has a remarkably low ratio of tensile strength to compressive strength, and is widely used in construction. However, the occurrence of cracks in a concrete structure is inevitable. Nevertheless, in the presence of adequate moisture, small cracks in the concrete structure exhibit a propensity to self-heal by getting filled due to the rehydration of cement particles and the subsequent precipitation of calcium carbonate (CaCO3). According to previous studies, the self-healing performance can be maximized by optimizing the temperature and pH to control the crystal formation of CaCO3. This study focused on the crystal form of CaCO3 generated in the self-healing of a cement-based composite material. To evaluate the self-healing performance depending on the type of aqueous solution and the temperature, the weight change, the weight change rate, and the porosity reduction in each case were evaluated. Moreover, to increase the generation of CaCO3 (which is a self-healing precipitate), nanosized ultrafine CO2 bubbles using CO2 gas were used, along with an adequate supply of Ca2+ by adjusting the aqueous solution (Ca(OH)2, CaO + ethanol). For greater pore-filling effects by controlling the CaCO3 crystal forms in the cement matrix, the change in the crystal form of the precipitated CaCO3 in the hardened cement paste with changing temperature was analyzed by scanning electron microscopy and X-ray diffraction. As a result, the possibility of the effective generation and control of vaterite with a dense pore structure together with calcite was confirmed by adjusting the temperature to approximately 40 °C at a pH of 12.
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Sarsam, Saad Issa. "Implication of Nondestructive Test NDT for Evaluation of Crack Healing in Asphalt Concret." Civil Engineering Beyond Limits 2, no. 1 (2020): 1–5. http://dx.doi.org/10.36937/cebel.2021.001.001.
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Asphalt concrete practices heavy loading and environmental impacts through the service life of the pavement. Micro cracks usually initiate and accumulate to form various types of distresses. However, asphalt concrete has the ability of self-healing under rest period and environment conditioning. Asphalt concrete is a composite material consisting of aggregates, bitumen, and air voids. Its mechanical behavior is complex due to its dependency of temperature, loading frequency, and strain level. In this investigation, asphalt concrete specimens of wearing course have been prepared in the laboratory and subjected to repeated indirect tensile stresses to initiate the micro-cracks. The test was stopped after 1200 load repetitions, and the specimens were stored in an oven at 60°C for 120 minutes to allow the crack healing process by external heating to start. Specimens were returned to the testing chamber and were subjected to another round of load repetitions. Specimens were tested before and after load repetitions and crack healing with the aid of ultrasonic pulse velocity traversing the specimen using pundit instrument. The healing indicator was the change in pulse velocity before and after the repeated load test and before and after healing process. It was concluded that the velocity decreases as the loading cycles proceeds indicating the start of damage, while the ultrasonic pulse velocity increases after the micro-crack healing process.
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Tomczak, Kamil, Jacek Jakubowski, and Łukasz Kotwica. "Key Factors Determining the Self-Healing Ability of Cement-Based Composites with Mineral Additives." Materials 14, no. 15 (2021): 4211. http://dx.doi.org/10.3390/ma14154211.
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This paper reveals the relationships between key factors that determine the ability of cementitious composites to self-heal autogenously and specific measures for quantifying the effects of this process. The following material factors: water-to-binder ratio (w/b), uniaxial compressive strength and age of the composite at the time of defect formation were considered, as well as the method and degree of damage to the tested material. The subjects of this study were mortars and concretes in which Portland cement was partially replaced, to varying degrees, with mechanically activated fluidized bed combustion fly ash (MAFBC fly ash) and siliceous fly ash. The samples were subjected to three-point bending or cyclic compression tests after 14 or 28 days of aging, in order to induce defects and then cured in water for 122 days. Microscopic (MO) and high-resolution scanning (HRS) observations along with computer image processing techniques were used to visualize and quantify the changes occurring in the macro-crack region near the outer surface of the material during the self-sealing process. Techniques based on the measurement of the ultrasonic pulse velocity (UPV) allowed the quantification of the changes occurring inside the damaged materials. Mechanical testing of the composites allowed quantification of the effects of the activity of the binder-supplementary cementitious materials (SCMs) systems. The analysis of the results indicates a significant influence of the initial crack width on the ability to completely close the cracks; however, there are repeated deviations from this rule and local variability of the self-sealing process. It has been shown that the compressive strength of a material is an important indicator of binder activity concerning crack width reduction due to self-sealing. Regardless of the crack induction method, the internal material changes caused by self-sealing are dependent on the degree of material damage.
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Zawad, Md Fahad Shahriar, Md Asifur Rahman, and Sudipto Nath Priyom. "Bio-Engineered Concrete: A Critical Review on The Next Generation of Durable Concrete." Journal of the Civil Engineering Forum 7, no. 3 (2021): 335. http://dx.doi.org/10.22146/jcef.65317.
Full textAbstract:
Concrete is a prerequisite material for infrastructural development, which is required to be sufficiently strong and durable. It consists of fine, coarse, and aggregate particles bonded with a fluid cement that hardens over time. However, micro cracks development in concrete is a significant threat to its durability. To overcome this issue, several treatments and maintenance methods are adopted after construction, to ensure the durability of the structure. These include the use of bio-engineered concrete, which involved the biochemical reaction of non-reacted limestone and a calcium-based nutrient with the help of bacteria. These bio-cultures (bacteria) act as spores, which have the ability to survive up to 200 years, as they are also found to start the mineralization process and the filling of cracks or pores when in contact with moisture. Previous research proved that bio-engineered concrete is a self-healing technology, which developed the mechanical strength properties of the composite materials. The mechanism and healing process of the concrete is also natural and eco-friendly. Therefore, this study aims to critically analyze bio-engineered concrete and its future potentials in the Structural Engineering field, through the use of literature review. The data analysis was conducted in order to provide gradual and informative ideas on the historical background, present situation, and main mechanism process of the materials. According to the literature review, bio-engineered concrete has a promising outcome in the case of strength increment and crack healing. However, the only disadvantage was its less application in the practical fields. The results concluded that bio-engineered concrete is a new method for ensuring sustainable infrastructural development. And also, it indicated that more practical outcome-based analysis with extensive application in various aspects should be conducted, in order to assess the overall durability.
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Vysotskaya, Marina, Anastasia Kurlykina, Artem Shiryaev, Anna Tkacheva, and Dmitry Litovchenko. "Modification of bituminous binders for guss asphalt." E3S Web of Conferences 274 (2021): 02011. http://dx.doi.org/10.1051/e3sconf/202127402011.
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Over the past few years, the research of the use of cast asphalt concrete mixtures in the upper layers of the coating of bridge structures has been actively carried out. The experience gained allows us to conclude that one of the most common effective ways to improve the durability and thermal stability of cast asphalt concrete pavements is the use of modified bituminous binders. The modified bitumen part of cast asphalt concrete acts as a medium capable of initiating the «self-healing» of the composite, independently eliminating structural defects. This study aims to research the rheological characteristics of modified bituminous binders. Bitumen grade BND 50/70 was used as a raw material in the study; the following types of additives were used as its modifiers: rubber modifier (RM), EVATHERM and SBS. The optimal concentrations of the proposed additives for modification allowing to achieve the effect of structuring the mastic component of cast asphalt concrete with insignificant increases in the temperatures of mixing and compaction of mixtures based on them have been revealed.
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Wang, Xianfeng, Wei Xie, Taoran Li, et al. "Molecular Dynamics Study on Mechanical Properties of Interface between Urea-Formaldehyde Resin and Calcium-Silicate-Hydrates." Materials 13, no. 18 (2020): 4054. http://dx.doi.org/10.3390/ma13184054.
Full textAbstract:
Microcapsule based self-healing concrete can automatically repair damage and improve the durability of concrete structures, the performance of which depends on the binding behavior between the microcapsule wall and cement matrix. However, conventional experimental methods could not provide detailed information on a microscopic level. In this paper, through molecular dynamics simulation, three composite models of Tobermorite (Tobermorite 9 Å, Tobermorite 11 Å, Tobermorite 14 Å), a mineral similar to Calcium-Silicate–Hydrate (C–S–H) gel, with the linear urea–formaldehyde (UF), the shell of the microcapsule, were established to investigate the mechanical properties and interface binding behaviour of the Tobermorite/UF composite. The results showed that the Young’s modulus, shear modulus and bulk modulus of Tobermorite/UF were lower than that of ‘pure’ Tobermorite, whereas the tensile strength and failure strain of Tobermorite/UF were higher than that of ‘pure’ Tobermorite. Moreover, through radial distribution function (RDF) analysis, the connection between Tobermorite and UF found a strong interaction between Ca, N, and O, whereas Si from Tobermorite and N from UF did not contribute to the interface binding strength. Finally, high binding energy between the Tobermorite and UF was observed. The research results should provide insights into the interface behavior between the microcapsule wall and the cement matrix.
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Vysotskaya, M., A. Kurlykina, D. Kuznecov, and A. Tkacheva. "ROAD SURFACE OF THE PAVEMENT COATING BRIDGE." Bulletin of Belgorod State Technological University named after. V. G. Shukhov 6, no. 4 (2021): 21–35. http://dx.doi.org/10.34031/2071-7318-2021-6-4-21-35.
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The current topic of the reliability of bridge structures in modern conditions and the role of the structural layers of the roadway (road surface) in increasing and maintaining their operational reliability and durability are considered. The existing standard designs of road surface clothing and the materials used for their arrangement are considered. The analysis and systematization of information from Russian and foreign sources on the construction of the clothing of the driving road indicates the prospects and technical and operational advantages of using cast asphalt concrete mixtures in the upper layers of the bridge pavement. It is noted that an effective road surface made of this material is capable of resisting existing loads, taking into account the specifics of the operation of the asphalt concrete surface during the established service life, additionally performing the protective waterproofing function of the metal structures of the bridge structure. The analysis of the literature demonstrates that active scientific research on the development and creation of effective cast asphalt concrete mixtures is primarily associated with the production and modification of its bituminous part, as a medium capable of initiating "self-healing" of the composite, independently eliminating structural defects. The rich experience of various methods of modifying bituminous binders, accumulated over the past few decades, allows to predict the prospects for using cast asphalt concrete in the construction of the roadway of bridge structures, based on improved binders, in order to create new high-quality materials that can improve the quality of the bridge network in the country.
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Krouma, Abla, and Zubair Imam Syed. "A Review on the Use of Engineered Cementitious Composite in Bridges." Materials Science Forum 860 (July 2016): 125–34. http://dx.doi.org/10.4028/www.scientific.net/msf.860.125.
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Engineered Cementitious Composite (ECC) is a material with high ductility, tensile strength and self-healing more than the standard concrete. Applications of ECC are beneficial due to its long life cycle, high strength, low cost in the long-term, low maintenance and environmentally friendly nature. Properties and hardened behavior of ECC highlights that ECC has a tight crack width development, which increases its ability to resist long-term effects of hot, frost and humid weather. Additionally, it results low water permeability coefficient and high steel corrosion resistance compared to other common alternative materials. One of the promising areas of application for ECC is in highway structures, especially highway bridges. Highway structures suffer constantly from adverse environmental loads and often require frequent repairing or replacing due to cracks; expansion; water and chlorides effects which cause steel corrosion or the slope between the pavement, slab and the support at the end of a bridge. Detailed review on different properties and characteristics of ECC and the current applications of ECC clearly highlights the motivation to enhance the use of ECC for bridge construction. In addition, ECC can be introduced in jointless bridges by putting an ECC link slab instead of the expandable mechanical joint.
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Vladimir, Erofeev, Al-Dulaimi Salman Dawood Salman, and Smirnov Vacili. "Bacteria for self-healing concretes." Russian journal of transport engineering 5, no. 4 (2018). http://dx.doi.org/10.15862/07sats418.
Full textAbstract:
Self-healing concrete is a product in which, with the help of microorganisms, limestone will be produced to fill cracks appearing on the surface of concrete structures. The author presents that specially selected types of bacteria of the genus Bacillus, a calcium-based nutrient known as calcium lactate, as well as nitrogen and phosphorus, are added to the ingredients of concrete when mixing it. These self-healing agents can be at rest inside the concrete for up to 200 years. Self-healing materials are a special type of materials that regenerate their strength properties after minor destruction caused to the material during its service life. Self-healing technology is particularly useful in the case of composite materials, as composites have low damage detection capacity and are susceptible to sudden and brittle fracture. Modern artificial materials have excellent mechanical properties. However, they lack the ability to self-repair. Therefore, in case of damage, there is a possibility of loss of mechanical strength, and over time, a gradual loss of functional strength in the absence of human intervention. Different types of bacteria, along with abiotic factors such as mineralization, pH value of the surrounding area, temperature, availability of nutrients and habitat composition, play a significant role in the deposition of calcium carbonate in a wide range of different media. There are four key factors that determine the MICP process: (i) calcium concentration, (ii) dissolved inorganic carbon concentration, (iii) pH value and (iv) presence of nucleation centers.
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Erofeev, Vladimir, Valeriy Kruglov, Nikolay Vatin, and Salman Dawood Salman Al-Dulaimi. "Intelligent composites and their use for self-healing concrete." Russian journal of transport engineering 6, no. 4 (2019). http://dx.doi.org/10.15862/12sats419.
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It is shown that during operation reinforced concrete structures are very often susceptible to cracking, which leads to a deterioration in the quality and expected life of them. The traditional methods of restoration and strengthening of structures are methods of building up, impregnating the structure of concrete with polymer and other materials, applying monolithic coatings or gluing metal polymer and other elements. Known repair methods are characterized by high complexity of execution, high cost, etc. It is shown that there is a pressing economic incentive for the development of concrete capable of self-repairing and repairing damage. Recently, tendencies toward the creation of new materials that are capable of actively interacting with external factors have been outlined towards world practice; such materials have received the name “intellectual”. The use of «intelligent» materials allows you to monitor and predict the state of various structures and structures, at the required time and even in hard-to-reach areas, significantly increase the resource of engineering systems and their reliability. It has been shown that to date, various chemical methods have been developed for creating self-healing concrete. One of the breakthrough technologies in the field of obtaining effective materials and structures based on them are biotechnologies based on the use of microorganisms. Many researchers have studied the use of calcite produced by bacteria to increase the life of concrete-based structures and restore buildings by eliminating cracks, increasing the strength of concrete, reducing permeability, and reducing water absorption. The article provides an overview of the work of foreign specialists in these areas.
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Dinarvand, Parya, and Alireza Rashno. "Review of the potential application of bacteria in self-healing and the improving properties of concrete/mortar." Journal of Sustainable Cement-Based Materials, June 10, 2021, 1–34. http://dx.doi.org/10.1080/21650373.2021.1936268.
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Chen, Qing, Xiangyong Liu, Hehua Zhu, et al. "Continuum damage-healing framework for the hydration induced self-healing of the cementitious composite." International Journal of Damage Mechanics, November 1, 2020, 105678952096803. http://dx.doi.org/10.1177/1056789520968037.
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The self-healing materials have become more and more popular due to their active capacity of repairing the (micro-) damages, such as the (micro-) cracks, the (micro-) voids and the other defects. In this paper, the thermodynamic based damage-healing framework is presented for the hydration induced self-healing composite with a compatible healing variable. The new variable is incorporated to consider the time-dependent properties of the hydration products, with which a new damage healing law is proposed. The hydration kinetics are employed to describe the healing process. The properties of the hydration products are arrived with the multiscale and multilevel homogenization scheme. The presented damage-healing model is applied to an isotropic cementitious composite under the tensile loading histories. The presented framework is compared with the classic continuum damage-healing theory and the experimental data. The results show that the presented damage-healing model is capable of describing the hydration induced self-healing of the cementitious composite. It can describe the behavior of the partially and fully healed concrete material. The effects of the healing time and the compatible healing variables on the damage-healing results are investigated based on our proposed framework.
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Siad, Hocine, Mohamed Lachemi, Mustafa Sahmaran, and Anwar Hossain. "MULTI-FUNCTIONAL CEMENTITIOUS COMPOSITES WITH SENSING AND HEALING CAPABILITIES." Proceedings of International Structural Engineering and Construction 4, no. 1 (2017). http://dx.doi.org/10.14455/isec.res.2017.101.
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For smart concretes to be developed, it must be gathering high mechanical and durability properties, in addition to satisfying special characteristics such as self-monitoring of damage. This study outlines attempts to develop advanced Engineered Cementitious Composites (ECC) with combined self-sensing and self-healing capabilities. The aim is to maintain or improve the high mechanical and ductility properties of ECC, while enhancing the self-monitoring and self-healing capabilities. To assure the self-sensing functionality, carbon-based materials with different volumes were incorporated in ECC formulations. The self-healing rates of control and piezoresistive ECC’s were assessed by pre-cracking specimens up to 60% of their original flexure deformations and left those samples to heal under moist curing. The mechanical performances and ductility were evaluated based on compressive and flexural strengths, and mid-span beam deflection capacity measurements. The self-healing/self-sensing efficiency was tested by assessing the electrical resistivity (ER) variations of cylindrical specimens. Mechanical results of carbon-based ECC mixtures showed better or comparable performances than the corresponding control ECC. This study also reveals that the type of carbon-based materials and moisture state of specimens considerably influence the self-sensing/self-healing ability of ECC mixtures.
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"Concrete Canvas: A Multifaceted Construction Material." International Journal of Recent Technology and Engineering 8, no. 3 (2019): 1898–901. http://dx.doi.org/10.35940/ijrte.c4462.098319.
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Cement concrete is a most used construction material, due to its enormous demand worldwide in the construction sector. Concrete serves many purposes in different adverse conditions, there are many advantages but there is one limitation that is concrete is not flexible. Concrete Canvas brought a revolutionary change in the construction materials called Geosynthetic Cementitious Composite Mats (GCCMs) which as many applications and used as an alternative to conventional concrete. It is a flexible, concrete canvas that gets hardens on hydration to form a thin, durable, waterproof and low-carbon concrete layer. Concrete Canvas may find its tremendous scope in the Construction sector as fire resistance and water proofing material. The concrete canvas has a self healing property thereby adds good benefit to the life of material and economically because of its zero percent repairs maintenance. Even though if the concrete canvas gets damaged after a period of time, it gets self healed with the contact of water which helps in the hydration process. This paper mainly focuses on the case study done on the applicability of concrete canvas for fire resistant, Water proof and bulletproofing with the help of AP State Police and to explore different applications in Construction sector as well as Defense sector.
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Hong, Minyoung, Indong Jang, Yongjun Son, Chongku Yi, and Woojun Park. "Agricultural by-products and oyster shell as alternative nutrient sources for microbial sealing of early age cracks in mortar." AMB Express 11, no. 1 (2021). http://dx.doi.org/10.1186/s13568-020-01166-5.
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AbstractBio-concrete using bacterially produced calcium carbonate can repair microcracks but is still relatively expensive due to the addition of bacteria, nutrients, and calcium sources. Agricultural by-products and oyster shells were used to produce economical bio-concrete. Sesame meal was the optimal agricultural by-product for low-cost spore production of the alkaliphilic Bacillus miscanthi strain AK13. Transcriptomic dataset was utilized to compare the gene expressions of AK13 strain under neutral and alkaline conditions, which suggested that NaCl and riboflavin could be chosen as growth-promoting factors at alkaline pH. The optimal levels of sesame meal, NaCl, and riboflavin were induced with the central composite design to create an economical medium, in which AK13 strain formed more spores with less price than in commercial sporulation medium. Calcium nitrate obtained from nitric acid treatment of oyster shell powder increased the initial compressive strength of cement mortar. Non-ureolytic calcium carbonate precipitation by AK13 using oyster shell-derived calcium ions was verified by energy-dispersive X-ray spectroscopy and X-ray diffraction analysis. Stereomicroscope and field emission scanning electron microscopy confirmed that oyster shell-derived calcium ions, along with soybean meal-solution, increased the bacterial survival and calcium carbonate precipitation inside mortar cracks. These data suggest the possibility of commercializing bacterial self-healing concrete with economical substitutes for culture medium, growth nutrient, and calcium sources.