Self-healing Cement Research Articles

Microbial self-healing cement-based materials co-reinforced by Mg2+: using recycled aggregates as carriers

Microbial self-healing cementitious materials have attracted widespread attention due to their targeted repair of cracks, but their practical application is limited by cost. In this study, self-healing mortar was prepared using recycled concrete fine aggregate as a cementitious material to investigate the effect of magnesium ions on crack repair, to explore the compatibility of self-healing components and cement, and to assess the cost and environmental impact of this self-healing mortar. The results showed that the mineralization efficiency was the highest at 31.1% with a Ca/Mg molar ratio of 3, and the 28 d crack repair rate reached 97.8%; yeast and peptones in the self-repairing system slowed down the rate of cement hydration, whereas magnesium chloride and calcium lactate facilitated the hydration reaction. The use of recycled concrete fine aggregate (RCA) reduces the cost of the self-repairing material and the CO2 emission, and improves the application of microbial self-healing cementitious materials potential.

Effect of shell composition on watertightness and mechanical performance of cement-based capsules used as self-healing additives of cement

The aim of this work is the development of cementitious macro-capsules for self-healing cement and concrete materials. Emphasis is placed on shell properties, including size, thickness, strength, and volume to active component ratio. This enhancement is aimed at protecting the healing agent and ensuring adequate reactivity upon crack formation, surpassing survivability considerations. To this direction, core/shell particles have been produced following the pan-coating method, while different types and concentrations of setting acceleration solutions for the shell stabilization were studied. The formation of core-shell capsules encompasses the formation a spherical core through agglomeration, followed by simultaneous spraying of cement powder and a setting acceleration solution for the shell formation, under continuous rotation. The microstructural characteristics of the shell were studied through scanning electron microscopy (SEM), while the reactivity of the protected core (reactive agent) inside the hardened mortar mixtures was evaluated using thermogravimetric analysis (TGA). Moreover, the crushing load of the capsules under compression and their survivability during mixing process were examined and interpreted in relation to their diameter, circularity, and shell thickness.The results revealed the ability of the encapsulation methodology proposed to tailor the shell properties and modify the capsule properties so as satisfy the requirements of different applications. The use of setting accelerators during shell formation proved essential for enhancing the density and the strength of the shell layer. As a consequence, this leads to macro-scale capsules with elevated survivability rate and core reactivity.

Experimental evaluation of the synergistic effect of calcium precursor dosage and bacterial strain interactions on the biogenic healing potential of self-healing cement mortar

This study investigates the microbially induced calcium carbonate precipitation (MICP) in repair mortar, focusing on the impact of calcium precursor dosage and bacterial strain selection. C6H10CaO6·xH2O and (CH3COO)2Ca·xH2O were used as calcium precursors at dosages of 0.1, 0.25, and 0.4 M with Bacillus subtilis VEB4, Priestia megaterium TSB16, and Halobacillus halophilus MCC2188 microbes. Quantitative assessment of precipitate and optimization of precursor dosages were conducted before making mortar cube specimens of size 70.6 × 70.6 × 70.6 mm with bacterial spores and nutrients immobilized in Modified Expanded Perlite. Cracked cube specimens underwent automated wet-dry cycles of 12 h daily for 60 days to induce healing. Comparative analysis of biomortar specimens showed P. megaterium as the most effective in compressive strength recovery (up to 89.33%) and crack healing with a maximum healed crack width of 0.64 mm, followed by B. subtilis with significant CSR improvements. H. halophilus, less efficient in non-saline conditions, healed cracks up to 0.48 mm. Calcium lactate was considered the better calcium source choice for B. subtilis and P. megaterium strains, whereas calcium acetate improved MICP by H. halophilus. Microstructural analysis of healed precipitates collected from cracked cubes identified distinct morphology of MICP and the presence of polymorphs viz, calcite, aragonite, and vaterite. Tailored selection and dosage of calcium precursors for each strain significantly enhanced MICP and improved the quality of healing products in cracks, advancing the understanding of self-healing construction biomaterials.

Analysis of the Current State of Research on Bio-Healing Concrete (Bioconcrete).

The relatively small tensile strength of concrete makes this material particularly vulnerable to cracking. However, the reality is that it is not always possible and practically useful to conduct studies on high-quality sealing cracks due to their inaccessibility or small opening width. Despite the fact that currently there are many technologies for creating self-healing cement composites, one of the most popular is the technology for creating a biologically active self-healing mechanism for concrete. It is based on the process of carbonate ion production by cellular respiration or urease enzymes by bacteria, which results in the precipitation of calcium carbonate in concrete. This technology is environmentally friendly and promising from a scientific and practical point of view. This research focuses on the technology of creating autonomous self-healing concrete using a biological crack-healing mechanism. The research methodology consisted of four main stages, including an analysis of the already conducted global studies, ecological and economic analysis, the prospects and advantages of further studies, as well as a discussion and the conclusions. A total of 257 works from about 10 global databases were analyzed. An overview of the physical, mechanical and operational properties of bioconcrete and their changes is presented, depending on the type of active bacteria and the method of their introduction into the concrete mixture. An analysis of the influence of the automatic addition of various types of bacteria on various properties of self-healing bioconcrete is carried out, and an assessment of the influence of the method of adding bacteria to concrete on the process of crack healing is also given. A comparative analysis of various techniques for creating self-healing bioconcrete was performed from the point of view of technical progress, scientific potential, the methods of application of this technology, and their resulting advantages, considered as the factor impacting on strength and life cycle. The main conditions for a quantitative assessment of the sustainability and the possibility of the industrial implementation of the technology of self-healing bioconcrete are identified and presented. Various techniques aimed at improving the recovery process of such materials are considered. An assessment of the influence of the strength of cement mortar after adding bacteria to it is also given. Images obtained using electron microscopy methods are analyzed in relation to the life cycle of bacteria in mineral deposits of microbiological origin. Current gaps and future research prospects are discussed.

Compressive strength, chloride-ion-penetration resistance, and crack-recovery properties of self-healing cement composites containing cementitious material capsules and blast-furnace-slag aggregates

Blast-furnace-slag aggregate (BFSA), a by-product of the steel industry, is an eco-friendly natural, aggregate substitute used in mortar and concrete. However, research on self-healing cement composites using BFSA is rare. In this study, the compressive strength, chloride-ion-penetration resistance, and crack-recovery properties of self-healing cement mortar samples prepared using cementitious material capsules (CMC) and BFSA of different ratios were examined and compared to a control sample. The test samples were: Control; C05B00 (5 % CMC and 0 % BFSA); C05B25 (5 % CMC and 25 % BFSA); C05B50 (5 % CMC and 50 % BFSA); C10B00 (10 % CMC and 0 % BFSA); C10B25 (10 % CMC and 25 % BFSA); and C10B50 (10 % CMC and 50 % BFSA). The compressive-strength recovery rate of the control stopped increasing after 28 days and was approximately 110 % on day 56 – that of C10B50 was approximately 121 %, (∼10 % greater than that of the control) and continued to increase even after 56 d. The chloride-ion-penetration resistance of C10B50 was excellent; the 28-day total charge was approximately 5858 C (∼ 40.2 % lower than that of the control). The crack-recovery rates, on day 28, of C05B50 and C10B25 were 71 % and 70 %, respectively (∼ 29–30 % higher than that of the control).

Study on the Repair Effect of Self-Healing Cementitious Material with Urea-Formaldehyde Resin/Epoxy Resin Microcapsule

Recent studies on microencapsulated self-healing cementitious materials have primarily focused on the particle size and preparation methods of the microcapsules. However, there has been limited attention paid to the microscopic aspects, such as the selection of curing agents and the curing duration of these materials. In this study, urea-formaldehyde resin/epoxy resin E-51 microcapsules were synthesized through in situ polymerization. This research investigates the feasibility of self-healing from a molecular mechanism perspective and evaluates the repair performance of microencapsulated self-healing cement mortar with varying microcapsule concentrations, curing agent types, and curing ages. The findings demonstrate that the microcapsule shells bond effectively with the cementitious matrix, with radial distribution function peaks all located within 3.5 Å. The incorporation of microcapsules enhanced the tensile strength of the modified cement mortar by 116.83% and increased the failure strain by 110%, indicating improved adhesion and mechanical properties. The restorative agent released from the microcapsule core provided greater strength after curing compared to the uncured state. Although the overall strength of the microencapsulated self-healing cement mortar decreased with higher microcapsule concentrations, the repair efficiency improved. The strength recovery rate of 28-day aged modified cement mortar had a significant improvement with the addition of X and Y curing agents, respectively.

Isocyanate microcapsules recovering automatically impermeability of cement paste through self-hydrophobic broken panels

Cracks are inevitable in the use of cement-based materials. It takes a lot of resources to repair these cracks and prolong the service life of cement-based materials. Self-healing cement-based materials that can automatically repair cracks and improve the self-healing ability of cement-based materials have become the focus of current research. The current self-healing systems achieve impermeability recovery of matrix by the filling cracks. Few scholars have paid attention to the impermeability recovery through self-hydrophobic broken panels. In this paper, SEM, FTIR, core content titration, water flux test and contact angle test were carried out. The morphology, composition, core content and impermeability recovery effect of self-healing cement paste were prepared and characterized. Carbon nanotubes are used to improve the water resistance of isocyanate microcapsules, which possess a diameter of 237.6 ± 59.1 μm, distinct core-shell structure, and good dispersibility. The residual core fraction is 58.2 % after 21 days in Ca(OH)2 aqueous solutions. The microcapsules maintain integrity without breakage when mixed with fresh cement paste and have good bonding compatibility with cement matrix. When microcapsules are embedded into cement paste, the cracks could break the microcapsules releasing isocyanate to wet the broken panels. The isocyanates react with the moisture with the formation of polyurea, changing the contact angle of broken panels from near 0° to 118.4 ± 0.1°. The hydrophobic panels could retard the water penetration and recover the impermeability of cement paste. Based on this, a new self-healing mechanism of self-hydrophobic fracture surface to realize self-healing of impermeability of cement matrix is proposed.

A viscosity-soluble type biomimetic self-healing cement slurry system

With the development of cementing slurry technology, cementing self-healing has become one of the most effective technologies to prevent and treat oil and gas channeling and improve long-term sealing capacity of cement sheath. To solve the technical problem of annulus oil and gas channeling caused by the long-term sealing failure of cement sheath, this paper researches and develops a kind of viscosity-soluble type biomimetic self-healing cement slurry system from the perspective of chemical biomimetics, based on the technical idea of “prevention before blocking”. Then, the engineering performance of this biomimetic self-healing cement slurry system and the mechanical property of self-healing set cement are evaluated respectively. In addition, the mechanical recovery capacity and permeability reducing rate of the self-healing set cement conserved with methane are evaluated by creating fractures through splitting. Finally, the healing mechanisms of the self-healing cement are analyzed by means of SEM microscopic test and infrared spectrography. And the following research results are obtained. First, the set cement has excellent mechanical property. When the compressive strength decreases by 15 %, the elastic modulus of set cement decreases by 41 %, showing good toughness to play the role of “first prevention”. Second, when meeting hydrocarbon, the damaged set cement is excited to generate a kind of viscosity-soluble type gelatinous ester substance, which re-bonds the skeleton of the set cement. When the self-healing set cement is conserved with methane, its compressive strength recovery rate is up to 94.5 %, bending strength recovery rate is 58.6 %, gas log permeability drops by 99 %, and liquid log permeability drops by 100 %, so as to realize “blocking later”. In conclusion, the viscosity-soluble type biomimetic self-healing cement slurry system can effectively achieve cementing integrity and long-term sealing integrity through self-healing after the damage of cement sheath, which provides a strong technical support for preventing the production safety hazard of sustained casing pressure in oil and gas wells and is beneficial to solve the technical problem of annulus oil and gas channeling caused by long-term sealing failure of cement sheath.

Study on Bionic Self-healing Cement Slurry System

Aiming at the technical problem of gas channing in annulus caused by long-term sealing performance failure of cementing cement ring, based on the technical idea of “prevent before plugging” and from the perspective of chemical bionics, a kind of bionic self-healing cement slurry system of dissolving viscosity was developed. The indoor evaluation results show that the cement stone has excellent physical properties. When the compressive strength is reduced by 15%, the elastic modulus of the cement stone is reduced by 41%, showing good toughness and playing the role of “first prevention”. When the damaged cement stone is excited by hydrocarbon, a kind of soluble gel ester can be formed, and the cement stone skeleton can be re-bonded. Under the condition of methane curing, the recovery rate of compressive strength is 99%, the recovery rate of flexure strength is 58.2%, the recovery rate of gas permeability is 96.4%, and the recovery rate of liquid permeability is 100%, playing the role of “post-plugging”. Therefore, it is concluded that the adhesive dissolving bionic self-healing cement technology can effectively realize the late integrity and realize the long-term sealing integrity after the cement ring is broken through self-healing, which provides a powerful technical support for preventing the abnormal annulus pressure, a hidden danger of oil and gas well production safety.

STUDY OF ADDITIVES FOR SELF-HEALING OF CEMENT SHEATH

The article discusses a study of cement sheath integrity improvement in oil and gas wells. This problem has been studied for more than 40 years. Nevertheless, every year it inextricably linked with the solution of current problems that challenge drilling specialists. Therefore, the search for solutions to problems in this area has great potential and prospects for further improvement. There are three conceptual approaches to the self-healing of cement stone: self-healing systems based on capsules (granules), in a vessel (fiber) shell and without shells. There is also a definition proposed by the Union of Laboratories and Experts in Building Materials. According to this concept, self-healing can occur during autogenous (natural) process, in which the filling of cement cracks occurs due to its own fund of non-hydrated particles when contact with water. Self-healing can also be autonomous (artificial, due to the introduction of additives such as polymers, bacteria and other components capable of either expanding or producing a substance that fills the void space under certain environmental conditions). However, despite the absence of auxiliary materials, autogenous healing is limited by the size of the cracks formed. Experience also shows that autonomous recovery also has negative aspects, which are associated with the characteristics of a particular material and medium - an activator. Therefore, in each case, the approach to solving the problem should be specific and unique. becomes more and more relevant due to the constant deterioration of mining and geological conditions in the process of drilling new wells. The process of adaptation to new conditions is After a series of successful studies aimed at the effect of water-oil-swelling additives on the self-healing ability of cement stone, the focus of the study was shifted to the problem of integrity of gas and gas condensate wells. In this regard, the study provides a detailed step-by-step description of the various processes aimed at finding a solution to the problem. The process of selecting a modifying additive with an assessment of the swelling ability to obtain the effect of self-healing cement stone in difficult mining and geological conditions is considered. Tests of additives in various conditions and environments are carried out. Attempts are made to create an experimental stand that allows simulating well conditions and evaluating the effect of stone restoration when creating artificial cracks. This study makes a significant contribution to the search and understanding of the performance of various additives in the formation environment. The creation of a test equipment is the first step towards modeling formation conditions at the surface. Further modernization of the stand will allow for more accurate tests and significantly reduce the time for selecting reagents. Thus, the use of this technology will improve the quality of well casing, as well as the safety of work in environmental terms.

Efficient healing of existed cracks in cement via synergistic effects of cement matrix activation and monomer polymerization

The effective repair of existing cracks can prolong the service life of infrastructures, which is of great significance for energy saving and emission reduction. A great deal of research on self-healing cement has been undertaken to efficiently prevent possible future cracking problems in buildings, but these methods do not deal with existing cracks. Herein, the efficient healing of existing cracks is achieved by the synergistic reaction of cement matrix activation and organic polymerization of sodium acrylate (ANa). ANa polymerization was systematically investigated for its effect on stimulated calcium silicate hydrate (C-S-H) and true healing systems in this study. The interconnected porous structure of sodium polyacrylate (PANa) observed during study suggested that ANa had been polymerized successfully under room temperature and the denser short rod-like C-S-H was also formed during the polymerization process. The formation of this organic-inorganic hybrid structure facilitates the rapid healing of existing cracks. When applied to cement, results showed that the compressive strength of specimens with the healing agent SS/PANa recovered 119.99% of its original strength and the micro-cracks of approximately 50 μm were completely sealed after 7-day curing. The ANa in the cracks helps enhance the reactivity of matrix and the polymerization improves the binding ability, forming an organic-inorganic composite network of the PANa and C-S-H. The composition and microstructure of the healed area revealed that the healing products were mainly composed of calcite (CaCO3), calcium hydroxide (CH), C-S-H and PANa.

Self-Healing Cement: A Review

The self-healing of cementitious materials can be achieved by precipitation of calcium carbonate through the enzymatic hydrolysis of urea. When a crack appears in cement, the damage can be repaired by allowing bacteria to encounter the water seeping through the crack. This forms a calcium carbonate, which heals the cracks. This occurs because microorganisms begin metabolizing and precipitating the mineral, healing the damage caused by the crack. Then, bacteria are incorporated into various containers, which release microorganisms by crushing, leading to the precipitation of calcium carbonate. In addition, this paper references the superabsorbent polymers (SAP) used for self-healing and hybrid organic-inorganic core–shell SAPs, a recently developed, state-of-the-art self-healing technology for cementitious materials.

H2S-responsive zwitterionic hydrogel as a self–healing agent for plugging microcracks in oil-well cement

During cementing construction, H2S gas leak from micro-cracks of cement ring or cementing interface, seriously damaging wellbore integrity and shortening the life of wells. Therefore, microcrack self-healing cement technology is of great significance for oil wells to maintain the durability of cement rings and adapt to complex underground environments. Herein, acrylamide (AM), acrylonitrile (AN) and N-vinylformamide (NVF) were used as functional monomers, and laponite was added to prepare Laponite-poly(acrylamide-acrylonitrile-n-vinylformamide) nanocomposite hydrogel (L-PMAN) with excellent mechanical strength as micro-crack repair agent for gas-triggered cementing cement sheath. Considering the difference of chemical environment in the process of wellbore cement slurry sealing and subsequent micro-fracture plugging, different structural units were selected to design amphoteric structure. The construction of zwitterionic structure makes it exhibit excellent swelling behavior in salt solution while maintaining 80% of the original mechanical strength. More importantly, after adding L-PMAN powder,cement stone (C1) can achieve good repair of microcracks under the trigger of H2S within 3 days, and the maximum gas breakthrough pressure can reach 2.5 MPa, indicating the great potentials of the L-PMAN for plugging microcracks in cement sheath.

Laboratory analysis of self-healing cement composition based on calcium lactate and bacteria

The research aims to evaluate the feasibility of using bacteria-based self-healing concrete using Portland cement and assess the effect of temperature on its performance. The results showed that the inclusion of calcium lactate and bacteria in the mixture accelerates the gain in compressive strength, but after 28 days of curing, the healing agent has no impact on the overall compressive strength value of the mixture. The crack width distribution analysis revealed an inverse relationship between crack width and self-healed area, with wider cracks having lower self-healing rates. Most of the healing occurs within 15 days, with only a small fraction healing between day 15 and 60 days. The study also showed that low temperatures do not produce self-healing in tested samples, and 25°C increases the self-healed area for all crack widths. Finally, chromatography tests of submerged water reveal that reaction to seal the cracks takes calcium from some external source. Keywords: self-healing cement; carbon emission; bacteria; calcium lactate; Portland cement.

Self-healing of cement mortar with partial replacement of cement with silica fume

Many attempts are being made to use alternative building materials for sustainable construction practices. Huge research work being conducted to identify materials which can be partially replaced by cement. Here we tried to use silica fume & pseudomonas fluorescens as a partial replacement of cement which is having capability of self-healing in cement mortar. Efforts has been made to develop resources with minimal use of fossil fuel based on non-renewable resources which has negative impact on environment. Hence reducing ecological disturbances making biologically efficient. Many industries have been exploring way for variety of bacterial properties to introduce in construction line. Cracks occurring in cement mortar will result into the decrease in its durability property. Hence there is a great demand for effective yet eco-friendly alternative technique for reducing cracks in cement mortar. Reduction of cost can be achieved by bacterial self-healing cement mortar in terms of damage spotting and maintenance of cement mortar. This project presents effect of the bacteria (pseudomonas fluorescens) on strength and durability properties of sustainable cement mortar. Optimized bacterial concentrations of 107 cells/ml and 108 cells/ml were used for designing of mortar mix proportions. Silica fume is added at 5%, 10%, 15%, 20%, and 25% by weight of cement for replacing of cement in the 1:3 cement mortar mix. Compressive strength, split tensile strength and flexural strength tests were performed on mortar cubes at the age of 7 & 28 days. The obtained results are evident that, addition of pseudomonas fluorescens bacteria in mortar mix will enhance the mechanical and durability properties in cement mortar.

Design and optimization parameters of cement-based spherical macrocapsules for self-healing cement applications

Encapsulated healing agents is a promising solution for extending the service life of critical infrastructure, providing long-term healing efficiency. This research focuses on the shell properties of cement-based spherical macro-capsules, aiming to achieve increased survivability during mixing of mortar mixtures and efficient triggering upon crack propagation. In this framework, the pan coating technique was examined for the production of capsules with a cementitious shell, developed for the protection of powder healing agents. The main properties that were studied included the crushing load as a function of capsules size and the shell hydration facilitated by different setting accelerators, and their consequent effect on the survivability and the triggering efficiency of the capsules. The results show that the use of setting accelerators allows the rapid densification of the shell microstructure and improves the crushing load of capsules, resulting in high survivability during mixing process. The enhanced compatibility of capsules with the matrix allowed the efficient triggering of capsules during crack propagation, initiating the autonomous healing process.

Studi Pengaruh Kontaminasi Properti Rheology Water Based Mud di Lapangan Sunyu

Studi Pengaruh Kontaminasi Properti Rheology Water Based Mud di Lapangan Sunyu

Influence of ultrasonic triggering parameters on recovery performance of microcapsule-mediated self-healing cement mortar

This study investigated the recovery performance of cement mortar incorporating UF/E microcapsules subjected to ultrasonic irradiations at different frequencies and powers. Results showed that ultrasonic trigger mode was superior to mechanical trigger mode in both strength and durability repair efficiency. At fixed frequency and time, there was a threshold value of ultrasonic power density towards the strength and durability repair efficiency. An appropriate increase in ultrasonic frequency can also effectively promote repair efficiencies. Pore structure analysis showed that ultrasonic wave has a competing effect (healing and damaging) on self-healing mortars. With increasing the ultrasonic power density, the damaging effect gradually became more significant, which was the essential reason for having a threshold value of ultrasonic power density.

Properties and mechanism of self-healing cement paste containing microcapsule under different curing conditions

This paper used the grouting method to maintain the cracks of subsea tunnel lining concrete, and the grouting materials was given the self-healing capacity by Urea-Formaldehyde/Epoxy (UF/E) microcapsules. The properties and mechanism of grouting slurry and hardened paste body exposed to seawater were investigated. Firstly, the microcapsule was synthesized by means of an in-situ polymerization method. Then the fluidity and dispersion of microcapsules were investigated. Besides, the mechanical properties and pore structure of the composites were measured. Meanwhile, the strength and porosity recovery rates were calculated after pre-damage treatment. Finally, the self-healing mechanism of microcapsule was researched through Scanning Electron Microscope (SEM) and Energy Dispersive Spectrometer (EDS). The results indicated that the microcapsule had a negative effect on the mechanical properties and porosity. With the increasing microcapsule dosage, the self-healing capacity first increased and then decreased, and the highest capacity was achieved with 1% dosage. Meanwhile, the self-healing capacity decreased with the increased pre-damage level. The SEM and EDS analysis showed that the microcapsule could repair the micro-cracks within the cement paste.

Elaboration of mending additives for the cement sheath repair

The dynamic loads and internal stresses applied onto a well during its operation period, gradually leads to deterioration of the cement sheath that usually exists behind the casings. Such mechanical and chemical exposure causes the cement to develop severe cracks that enables cross feeds behind casings and uncontrollable flow between formations leading to oil-gas mixture and migration of hydrocarbons into freshwater aquifers causing immediate harm to local water sources [1], affecting the zonation capability of the cement itself behind the casings.
 This issue has been in the industry of oil and gas for ages, leading us to investigate the possibility of maintaining the integrity of the cement stone behind the casings through the principle of self-healing materials, through this principle a self-healing cement was formulated adding secret agents into the ordinary cement powder which will be able to cure cracks in the cement stone under special conditions without human intervention. This can be an effective measure for loss of well integrity prophylaxis and eliminates well shutdowns for well workover operations.