Self-healing Concrete Research Articles

Experimental on repair performance and complete stress-strain curve of self-healing recycled concrete under uniaxial loading

The inherent brittle nature, low tensile strength and poor cracking resistance of concrete make it prone to cracking, which leads to the reduction of structural load-bearing capacity. Therefore, based on the loose and porous characteristics of the old mortar attached to the surface of the recycled aggregate, this study prepared self-healing recycled concrete with recycled aggregate as microbial carrier and investigated its crack healing capacity and uniaxial compressive stress–strain full curve. 24 specimens were designed for loading tests, namely: carrier adsorbed bacteria recycled concrete (C-BRC), direct-blended bacterial recycled concrete (D-BRC), no bacteria recycled concrete (NRC), and recycled aggregate concrete (RAC), and were further explored by Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS) and Mercury Intrusion Porosimetry (MIP) tests. The crack healing capacity, stress process and failure mode of each specimen were observed, and the repair performance, complete stress–strain curve, peak stress, peak strain, elastic modulus and Poisson's ratio of each specimens under different conditions were analyzed, and the mechanism analysis of mechanical properties recovery were investigated. The study showed that when the specimen were repaired for 28 days, all the cracks in the C-BRC were repaired to 100% with a maximum healing crack width of 0.27 mm. At the same healing time, the C-BRC had the best healing capacity, followed by the D-BRC, and the NRC had the lowest. The geometric characteristics of the stress–strain curve for self-healing recycled concrete prism specimen under uniaxial compression and the failure mode were similar to those of recycled concrete and ordinary concrete. At 56 days after healing, the peak stress recovery ratio of the C-BRC reached 86.94%, which was 37.01 MPa. The repair performance, peak stress, peak strain and elastic modulus of each specimens increased in different degrees with the increase of healing time. The Poisson's ratio of self-healing recycled concrete was measured to be roughly 0.16–0.23, which is slightly larger than that of recycled concrete.

Self-healing concrete-What Is it Good For?

Self-healing of concrete is the process in which the material regenerates itself repairing inner cracks. This process can be produced by autogenous or autonomous healing. Autogenous healing is a natural process, produced by carbonation and/or continuing hydration. Autonomous healing is based on the use of specific agents to produce self-healing, which can be added directly to the concrete matrix, embedded in capsules or introduced through vascular networks. Some examples are superabsorbent polymers, crystalline admixtures, microencapsulated sodium silicate, and bacteria. This review is structured into two parts. The first part is an overview of self-healing concrete that summarises the basic concepts and the main advances produced in the last years. The second part is a critical discussion on the feasibility of self-healing concrete, its possibilities, current weaknesses, and challenges that need to be addressed in the coming years.

Review: Microbial induced mineralization of calcium carbonate for self-healing concrete

Abstract. Elkhateeb WA, Elnahas MO, Daba GM. 2021. Review: Microbial induced mineralization of calcium carbonate for self-Healing concrete. Asian J Nat Prod Biochem 19: 1-9. Low-cost solutions achieving concrete self-healing are attracting researchers attention. Generally, concrete self-healing mechanism has been so far accomplished by three approaches: autogenous healing, encapsulation of polymeric material, and microbial induced mineralization of calcium carbonate. Microbial approach seems like an attractive potent, relatively cheap way to achieve concrete self-healing. Hence, this review elucidates the microbial concrete self-healing mechanisms, and compare the roles of fungal and bacterial mediated self-healing concrete.

Self-Healing Performance of Biogranule Containing Microbial Self-Healing Concrete Under Intermittent Wet/Dry Cycles

Development of self-sensing and self-healing concrete is essential to minimize the labour-intensive monitoring and repair activities conducted for the maintenance of concrete structures. A type of self-healing concrete can be achieved by using microbial agents that induce calcium carbonate precipitation inside a concrete crack. Recently, biogranules consist of nitrate reducing microorganisms were presented as a new generation microbial healing agent and biogranule containing specimens revealed decent healing performance under completely submerged conditions. However, their performance under intermittent wetting conditions, a common case for various concrete structures, remains unknown. This study presents the self-healing performance of biogranule containing biomortar specimens under intermittent wet/dry conditions. In-house produced biogranules were incorporated into mortar specimens at a dose of 1.45% w/w cement (1.00% of bacteria w/w cement) and self-healing performance of cracked specimens were investigated under alternating wet/dry conditions for a crack width range of 50 to 600 µm. Upon alternating wet/dry treatment for 4 weeks, cracks up to a 400 µm crack width were effectively healed in biomortar specimens. Their water tightness regain was 44% better than control specimens due to their enhanced healing performance. Overall, non-axenic biogranules appear to be useful in development of self-healing bioconcrete for applications under spraying or intermittent wetting conditions.

Comprehensive microbiological studies on screening bacteria for self-healing concrete

The present study majorly focused on the selection of suitable bacteria through microbiological studies for concrete crack healing. However, Bacillus species of non-pathogenic type bacteria's Viz., Bacillus subtilis, Bacillus cereus, Bacillus licheniformis, and Bacillus halodurans were used as self-healing agents. Also conducted various microbiological studies such as gram staining process, biofilm, Exopolysaccharide, Endospores, Urease Enzyme, and Calcium Carbonate formations. Similarly, the growth pattern of bacteria was measured in different temperatures (25 °C, 30 °C, 35 °C, 37 °C, and 60 °C), environments (such as pH of 3,7,8,9,10,11,12,13, and 14), and concrete composition medium. The gram staining process has identified that the above four bacteria have gram-positive strains and a rod-like shape. The B.halodurans and B.licheniformis have shown more spore formation, urease enzyme production, Exopolysaccharide production, biofilm formation, and calcium carbonate formation than other cultures. The B.licheniformis has shown the highest growth rate at various temperatures and environmental conditions. However, in the case of concrete composition medium B.halodurans has shown the highest growth rate. To determine the above four bacteria's crack healing ability, 40 MPa strengthened concrete samples are prepared and, then 65% and 75% of stress level concentration were applied to form cracks. However, Ultra-sonic pulse velocity values and water absorption values are taken for the concrete specimens to assess the healing capability. From the obtained results, B.halodurans has shown an ultrasonic pulse velocity value of 4.6 km/s and with 1.71% of water absorption, which is optimum among other bacterial cultures. The present study strongly recommends using B.halodurans as self-healing agents in concrete repair works.

Feasibility and Compatibility of a Biomass Capsule System in Self-Healing Concrete.

Cracking can facilitate deteriorations of concrete structures via various mechanisms by providing ingress pathways for moisture and aggressive chemicals. In contrast to conventional maintenance methods, self-healing is a promising strategy for achieving automatic crack repair without human intervention. However, in capsule-based self-healing concrete, the dilemma between capsules’ survivability and crack healing efficiency is still an unfathomed challenge. In this study, the feasibility of a novel property-switchable capsule system based on a sustainable biomass component, polylactic acid, is investigated. Capsules with different geometries and dimensions were studied focusing on the compatibility with concrete, including survivability during concrete mixing, influence on mortar and concrete properties, and property evolution of the capsules. The results indicate that the developed elliptical capsules can survive regular concrete mixing with a survival ratio of 95%. In concrete containing 5 vol.% of gravel-level capsules, the compressive strength was decreased by 13.5% after 90 days, while the tensile strength was increased by 4.8%. The incorporation of 2 vol.% of sand-level capsules did not impact the mortar strength. Degradation and switchable properties triggered by the alkaline matrix of cement were observed, revealing the potential of this novel biomass capsule system in achieving both high survivability and self-healing efficiency in concrete.

Microbial induced calcium carbonate precipitation study using Bacillus subtilis with application to self-healing concrete preparation and characterization

This study aimed to develop novel bacteria-based self-healing concrete by microbial induced calcium carbonate precipitation mechanism. A group of spore-forming bacterium related with gen Bacillus subtilis were selected for cultivation at elevated pH solution. The derived alkali-resistant Bacillus subtilis M9 was applied for biomineralization test whereas the precipitate mineral was calcium carbonate in calcite phase according to X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) results. With B. subtilis M9 as the healing agent, the self-healing concrete beam specimens were then prepared by incorporating polyvinyl alcohol fibers. Air-entraining agent was utilized to yield micro pores in cement paste mixture to provide ecological niches for microbe. 3-point-bending test was conducted to form 0.3-mm-width cracks on the beam bottom. After 28 days curing, the micro cracks were autonomously healed with calcium carbonate precipitation fillings due to the bacteria metabolic activity. The sequent SEM tests implied that calcite is the dominant mineral phase with some bacterial imprints on the crystal surface. Furthermore, flexural strength of the sealed beam subjected to repeated bending was enhanced by about 14% compared to residual flexural strength. The beam flexural strength recover was realized by remediation of the cracks in matrix as well as repairing of fiber–matrix interface bond.

The Impact of Using Nano Self-Healing Concrete in Flexible Houses

In recent decades, modernist ideology almost lodging questions the designs of life and, approaches the building as something that can alter over time and, not harm the environment. On the other hand, a wide range of advanced materials has affected the prospects of science and technology in construction. In the same way, self-healing materials lead to the advancement of economical innovation within the field of nanotechnology. Although it has been claimed that self-healing materials a sort of Nano materials to form multidimensional values for sustainability and green buildings, the results of value creation are still insufficiently understood and taken into account in decision making. For this reason, the purpose of this project is to examine the structure of self-healing materials and their impact on the design process of green buildings. This paper provides a comprehensive assessment of nanomaterial-based self-healing concrete using grounded theory, a type of qualitative study that includes environmental impacts, sustainability, and methods of use and its placement in the design of flexible houses by a type of quantitative method, a Causal-Comparative. It will be discussed and sought to determine what the future of Nano-materials and their implications for flexible architecture will be.

LABORATORY STUDY ON SELF HEALING CONCRETE PAVEMENT – REVIEW PAPER

Concrete could be a variable material having several blessings. thus it's the foremost wide used material within the housing industry. several researchers created makes an attempt to use waste materials with the target of eliminating the disposal issues and at constant time up the properties of concrete. Self-healing concrete is that the want of the hour within the current state of affairs. Deterioration is inevitable though innovations square measure streaming within the field of concrete technology. Admixtures return handy in economy purpose of read for achieving self healing in concrete structures thus on scale back the cracks within the earlier stage itself. Self-healing technology could be a new field at intervals material technology. It represents a revolution in materials engineering and is dynamical the means that materials behave. Incorporating self healing technology into the road style method has the potential to rework building and maintenance processes by increasing the period of time of roads and eliminating the necessity for road maintenance.

Bio-Mineralization process on concrete substituted with different types of waste materials

Million tons of waste materials were produced in the world each year and most of it is not recyclable. To protect the environment from pollution and depletion, it is imperative to find explication for the safe disposal of waste materials. Using waste material in concrete production is a propitious method for eliminating the waste and reducing the cost of concrete. Also, the green concrete technology is expanding, it is necessary to utilize wastes in concrete that is generated from all the sectors. In construction large amounts of concrete from buildings was generated and demolitions made up 30-40 % of total wastes. Around 33 tons of Copper slag is produced across the world and 6 to 6.5 tons in India. Electronic waste is emerging as a serious public health and environmental issue in India and approximately 2 million tons of e-waste is generated annually. Concrete produced from wastes will have declination over the strength and it is necessary to improve the properties by some other technique. Self-healing concrete is a brand-new technology that ‘heals’ its own cracks and indicates a promising future in reducing the inevitable deterioration of concrete structures and the high maintenance costs involved. This research includes the inclusion of waste materials into the concrete and determination of compressive Strength of waste substituted concrete. Three major Wastes such as Demolition Wastes, Copper slag and E-Wastes were chosen to replace for aggregate and Bacteria subtilis a spore forming bacteria was used as an admixture to improve the properties of concrete. From the results obtained it has been observed that self-healing technology proves to be the fruitful and considerable increase in mechanical properties.

Innovative Use of Self-Healing Concrete for Sustainable Infrastructure

Self-healing concrete has emerged as a promising technology in the field of sustainable infrastructure due to its ability to repair cracks and prolong the lifespan of structures. This innovative material has the potential to revolutionize the construction industry by reducing maintenance costs, minimizing environmental impact, and enhancing the durability of infrastructure. In this abstract, we explore the concept of self-healing concrete, its mechanisms, and its application in creating sustainable infrastructure. The concept of self-healing concrete involves the incorporation of various healing agents within the concrete matrix, which are activated upon the occurrence of cracks or damage. These healing agents can be in the form of capsules, fibres, or other admixtures. When cracks occur, these agents are released and react with the surrounding environment to initiate the healing process. The healing agents can fill the cracks, restore the structural integrity, and prevent further deterioration, thus extending the service life of the infrastructure. The innovative use of self-healing concrete presents significant opportunities for sustainable infrastructure development. By incorporating healing agents, this technology enables autonomous repair of cracks, reduces maintenance costs, and extends the lifespan of structures. Furthermore, self-healing concrete contributes to sustainability by minimizing environmental impact and enhancing durability. Its wide-ranging applications make it a promising solution for creating resilient infrastructure that meets the challenges of the future. Embracing self-healing concrete in construction practices will undoubtedly revolutionize the industry and pave the way for a more sustainable built environment.

On the Applicability of a Precursor Derived from Organic Waste Streams for Bacteria-Based Self-Healing Concrete

Bacteria-based self-healing concrete has the ability to heal cracks due to the bacterial conversion of incorporated organic compounds into calcium carbonate. Precipitates seal the cracks, theoretically increasing the service life of constructions. The aim of this paper is to propose a precursor for bacteria-based self-healing concrete derived from organic waste streams, produced is in line with the circular economy principle and ideally more affordable than other substrates. To verify the applicability of the proposed healing agent, some fundamental requirements of the proposed system are studied, such as its influence on functional properties, crack sealing capacity and evidence of bacterial activity in concrete.

Engineering application of microbial self-healing concrete in lock channel wall

In this paper, the engineering application of microbial self-healing concrete in ship lock engineering was studied. Researches including the design and batch preparation of microbial self-healing agent, and laboratory tests of microbial self-healing concrete were carried out. A class of self-healing agents containing microbial spores and calcium sources was designed and batch-produced by spray drying method, which was tested to show that the addition of self-healing agent in concrete has no significant effect on the performance of the concrete mixture and the development of the compressive strength of hardened concrete specimens. Then the self-healing agents were applied to the production of commercial concrete, and a corresponding microbial concrete production system was formulated. After applying the produced microbial self-healing concrete to the side wall of the ship lock, it was observed that the cracking of the concrete was completely healed after 60 days, and the leakage of the crack was effectively blocked. Thus microbial self-healing concrete is expected to be widely used in concrete crack self-healing in hydraulic environment.

Self-healing Concrete Technology Utilizing Bacteria

Self-healing Concrete Technology Utilizing Bacteria

A review of bacteria-based self-healing concrete

A review of bacteria-based self-healing concrete

Experimental Evaluation of Bacterial Self-Healing Concrete Embodying Bacillus Pumilus Cured in Normal and Accelerated Modes

Experimental Evaluation of Bacterial Self-Healing Concrete Embodying Bacillus Pumilus Cured in Normal and Accelerated Modes

Recent advances in microbial viability and self-healing performance in bacterial-based cementitious materials: A review

In efforts to secure long-term concrete durability performances, studies on bio-mineralization mediated self-healing concrete as an eco-friendly and sustainable crack-healing method have been widely conducted. In the self-healing mechanism using bio-mineralization, carbonate minerals generated by biochemical metabolism of bacteria fill cracks and/or voids in the concrete. The microbial viability and biochemical metabolism in the concrete could be influenced by various environmental factors in the interior and exterior of the concrete. Moreover, the bacterial viability could be significantly reduced upon exposure to extreme environments formed as the cement hydration proceeds during concrete curing. This paper covers the various factors affecting the bacterial viability and self-healing performance. Furthermore, advanced applications for enhancing the bacterial viability and self-healing efficiency are reviewed. The present review paper summarizes the current issues and proposes needs for further research in order to promote the efficient application of bio-mineralization for self-healing concrete.

Self-healing of early-age cracks in cement mortars with artificial functional aggregates

Cracking seriously affects the functionality and durability of the concrete structure. Therefore, the development of robust self-healing concrete is important to extend the service life of the structure. In this study, artificial functional aggregates with fly ash, silica fume, metakaolin, limestone powder and sodium carbonate powder were designed and prepared by the powder granulation technology to promote the self-healing efficiency of concrete. Mortar specimens with artificial functional aggregates which partially replaced the sand were prepared to verify the feasibility of the approach. Crack self-healing efficiency was evaluated by visual observation and the water ingress test. In addition, healing products formed in the crack were analyzed with XRD, TG and SEM, respectively. Experimental results indicated that the artificial functional aggregates were well combined with the mortar matrix and could be intersected by cracking. The addition of artificial functional aggregates improved the self-healing capacity of mortar specimens. Mortar specimens with artificial functional aggregates exhibited higher closure ratio of surface crack and better regain of water tightness compared with the control specimens. The maximum crack width that can be healed was about 0.47 mm in the mortar specimen with artificial functional aggregates. Microstructure investigation showed that the major healing products in the crack mouth were calcite precipitations which firstly deposited on both walls of the crack and then gradually overlapped together to become denser and denser with the extension of healing time. More calcium carbonate precipitations were observed in internal crack of mortars with artificial functional aggregates compared to the control mortar due to the effective supply of carbonate ions from the artificial functional aggregates. Typical hydration product C-S-H gel was also detected by SEM observation in the internal crack wall.

RESEARCH ON THE USE OF SELF-HEALING CONCRETE

Concrete is currently the main man-made structural building material. It takes on extreme loads, undergoes periodic processes of freezing and thawing, which affects its integrity and, as a result, the process of cracking is observed. A promising direction of development in improving the performance properties of concrete is the use of self-healing elastic concrete, which allows increasing the strength characteristics of the concrete structure and preventing corrosion of the reinforcing elements. The article discusses the technology for the production of self-healing concrete, indicates the necessary conditions for self-healing and defines the features of its application. Also, the calculation of production costs was made and the economic effect from the basic version of the production of self-healing concrete was calculated, the relationship between the service life and cost was determined using the correlation method. As a result of the work, it was confirmed that the new method of self-healing has the prospect of implementation and is more effective in places where the production of repair work, and regular inspection of the condition of structures, in practical terms, is impossible: underground construction, underwater construction, high-rise buildings, bridge-type transport structures. The use of self-healing concrete ensures the preservation of the bearing capacity of concrete and reinforced concrete structures, which significantly increases the service life without damage and equally helps to reduce additional material costs for maintaining the facility. The same research method revealed that bio-concrete with the use of Bacillus subtilis bacteria allows reducing the level of environmental pollution by minimizing hydrocarbon emissions during the preparation of the mixture.

Application potential of Bacillus megaterium encapsulated by low alkaline sulphoaluminate cement in self-healing concrete

With the help of microbial mineralization to accelerate carbonate deposition, microbial self-healing concrete has developed into a promising technology because it is environmentally friendly. At the same time, how to assemble properly microorganisms and nutrients to reduce the negative impact on the performance of concrete itself has become a bottleneck of this technology. In this research, microbial spores of Bacillus megaterium, nutrients and low-alkaline carriers were assembled as a whole by extrusion. Low alkali calcium sulphoaluminate (CSA) cement was used as the carrier to protect spores from the high alkalinity environment caused by cement hydration. After studying the protective effect of this assembly method on spores, this integrated self-healing agent was applied in concrete, and then repairing efficiency of cracks was evaluated by area repairing ratio, recovery of water resistance, recovery of resistance to chloride ions and healing depth. Meanwhile, the repairing products were analyzed by XRD and SEM equipped with an EDS. Moreover, two different nutrients were used as precursors for microbial mineralization, and their negative effects have also been studied. The results showed that Bacillus megaterium could use glucose and calcium lactate as the precursors, and this new repairing system significantly improves the efficiency of self-healing. Compared to glucose, calcium lactate has a better repair effect when used as a precursor, and the average healing depth reached 4000 µm. At the same time, CSA cement was an excellent carrier for spores and could reduce the negative impact of nutrients on concrete when microorganisms and nutrients were assembled with CSA cement.