scholarly journals Comparison of Microbially Induced Healing Solutions for Crack Repairs of Cement-Based Infrastructure

2021 ◽  
Vol 13 (8) ◽  
pp. 4287
Author(s):  
John Milan van der Bergh ◽  
Bojan Miljević ◽  
Snežana Vučetić ◽  
Olja Šovljanski ◽  
Siniša Markov ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Service Life ◽  
Cementitious Materials ◽  
Bacterial Suspension ◽  
Self Healing ◽  
Construction Costs ◽  
Recovery Processes ◽  
Concrete Crack ◽  
Crack Repair ◽  
Water Absorption Test

Reinforced concrete crack repair and maintenance costs are around 84% to 125% higher than construction costs, which emphasises the need to increase the infrastructure service life. Prolongation of the designed service life of concrete structures can have significant economic and ecological benefits by minimising the maintenance actions and related increase of carbon and energy expenditure, making it more sustainable. Different mechanisms such as diffusion, permeation and capillary action are responsible for the transport of fluids inside the concrete, which can impact on the structure service life. This paper presents data on microbially induced repair and self-healing solutions for cementitious materials available in the contemporary literature and compares results of compressive strength test and capillary water absorption test, which are relevant to their sealing and mechanical characteristics. The results of the repair and self-healing solutions (relative to unassisted recovery processes) were “normalized.” Externally applied bacteria-based solutions can improve the compressive strength of cementitious materials from 13% to 27%. The internal solution based solely on bacterial suspension had 19% improvement efficacy. Results also show that “hybrid” solutions, based on both bio-based and non-bio-based components, whether externally or internally applied, have the potential for best repair results, synergistically combining their benefits.

Screening of Different Encapsulated Polymer-Based Healing Agents for Chloride Exposed Self-Healing Concrete Using Chloride Migration Tests

2018 ◽  
Vol 761 ◽  
pp. 152-158 ◽  
Author(s):  
Philip van den Heede ◽  
Bjorn van Belleghem ◽  
Maria Adelaide Araújo ◽  
João Feiteira ◽  
Nele de Belie
Keyword(s):  
Service Life ◽  
High Viscosity ◽  
Cementitious Materials ◽  
Self Healing ◽  
Polymer Precursor ◽  
Marine Environments ◽  
Steel Reinforced Concrete ◽  
Low Viscosity ◽  
Chloride Migration ◽  
The One

The service life of steel reinforced concrete in aggressive marine environments could be increased substantially by embedding a self-healing mechanism that ensures autonomous healing of cracks upon their occurrence. Previous proof-of-concept experiments have shown that the incorporation of encapsulated polymer-based healing agents (HAs) counts as a very appropriate way to achieve this goal. Over the years, several polymer-precursor-capsule systems have been developed in that perspective at our laboratory. Cementitious materials containing either commercial or in-house developed encapsulated HAs have been subjected to preliminary feasibility tests (water absorption, permeability tests, etc.). However, these experiments did not yet allow for a fast and straightforward assessment of the self-healing efficiency (SHE) in relation to the expected durability and service life performance of the material. This approach would have many advantages when having to select the most suitable polymer-precursor-capsule system for a particular concrete application. In this paper, a modified chloride migration test based on the one prescribed in NT Build 492 has been proposed to support the development of self-healing concrete for marine environments. Four polymer-based HAs have been screened that way, i.e. an in-house developed high-viscosity polyurethane (PU) precursor, a commercial low-viscosity PU precursor, the same commercial PU precursor with addition of accelerator and benzoyl peroxide (BPO), and an in-house developed 2-component acrylate-endcapped precursor + cross-linker. For now, a highly repeatable SHE value of 100% could only be obtained for the second option.

scholarly journals Encapsulation Techniques and Test Methods of Evaluating the Bacteria-Based Self-Healing Efficiency of Concrete: A Literature Review

2020 ◽  
Vol 62 (1) ◽  
pp. 63-85
Author(s):  
Rahul Roy ◽  
Emanuele Rossi ◽  
Johan Silfwerbrand ◽  
Henk Jonkers
Keyword(s):  
Service Life ◽  
Polymeric Materials ◽  
Cementitious Materials ◽  
Test Methods ◽  
Self Healing ◽  
Load Factors ◽  
Healing Efficiency ◽  
Healing Agent ◽  
Maximum Crack ◽  
Encapsulated Bacteria

AbstractCrack formation in concrete structures due to various load and non-load factors leading to degradation of service life is very common. Repair and maintenance operations are, therefore, necessary to prevent cracks propagating and reducing the service life of the structures. Accessibility to affected areas can, however, be difficult as the reconstruction and maintenance of concrete buildings are expensive in labour and capital. Autonomous healing by encapsulated bacteria-based self-healing agents is a possible solution. During this process, the bacteria are released from a broken capsule or triggered by water and oxygen access. However, its performance and reliability depend on continuous water supply, protection against the harsh environment, and densification of the cementitious matrix for the bacteria to act. There are vast methods of encapsulating bacteria and the most common carriers used are: encapsulation in polymeric materials, lightweight aggregates, cementitious materials, special minerals, nanomaterials, and waste-derived biomass. Self-healing efficiency of these encapsulated technologies can be assessed through many experimental methodologies according to the literature. These experimental evaluations are performed in terms of quantification of crackhealing, recovery of durability and mechanical properties (macro-level test) and characterization of precipitated crystals by healing agent (micro-level test). Until now, quantification of crack-healing by light microscopy revealed maximum crack width of 1.80mm healed. All research methods available for assesing self-healing efficiency of bacteria-based healing agents are worth reviewing in order to include a coherent, if not standardized framework testing system and a comparative evaluation for a novel incorporated bacteria-based healing agent.

scholarly journals Evaluation of the chloride penetration and service life of self-healing concretes activated by crystalline catalyst

2018 ◽  
Vol 11 (3) ◽  
pp. 544-563 ◽  
Author(s):  
P. HELENE ◽  
G. GUIGNONE ◽  
G. VIEIRA ◽  
L. RONCETTI ◽  
F. MORONI
Keyword(s):  
Compressive Strength ◽  
Service Life ◽  
Blended Cement ◽  
Good Alternative ◽  
Chloride Ions ◽  
Self Healing ◽  
Chloride Permeability ◽  
Concrete Mixtures ◽  
Colorimetric Indicator ◽  
Astm C1202

Abstract The main cause of concrete structures deterioration is related to the resistance against the penetration of aggressive agents. Aiming at increase the impermeability and reduce the diffusivity of concrete elements, making it less susceptible to the ingress of chloride ions, the use of crystalline catalyst emerges as a good alternative. Its mechanism of autogenous healing enhances the natural pore-filling process of concrete. The aim of this study is to investigate the influence of the use of crystalline catalyst on the chloride ions penetration and service life prediction of concrete. For the concrete mixtures production, it was used blast-furnace slag blended cement, three different water/cement (w/c) ratios (0.45; 0.55; 0.65), with and without crystalline catalyst, totaling six different mixtures. The concrete specimens were cured in a moist chamber and tested at 28 and 91 days. It was performed tests of compressive strength, rapid chloride permeability (ASTM C1202:12), and silver nitrate colorimetric indicator. The results show that, compared to the reference mixture, the use of crystalline catalyst conserved the compressive strength and reduced the chloride ions penetration up to 30%, increasing service life up to 34%.

scholarly journals Key Factors Determining the Self-Healing Ability of Cement-Based Composites with Mineral Additives

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4211
Author(s):  
Kamil Tomczak ◽  
Jacek Jakubowski ◽  
Łukasz Kotwica
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Crack Width ◽  
Defect Formation ◽  
Cementitious Materials ◽  
The Self ◽  
Supplementary Cementitious Materials ◽  
Self Healing ◽  
Key Factors ◽  
Important Indicator

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.

scholarly journals Concrete crack repair analysis with metakaolin-based geopolymer cement

2020 ◽  
Vol 13 (2) ◽  
pp. 298-313
Author(s):  
B. J. FRASSON ◽  
F. PELISSER ◽  
B. V. SILVA
Keyword(s):  
Compressive Strength ◽  
Epoxy Resin ◽  
Mechanical Performance ◽  
Epoxy Adhesive ◽  
Steel Sheets ◽  
Concrete Crack ◽  
Repair Materials ◽  
Crack Repair ◽  
Geopolymer Cements ◽  
Geopolymer Cement

Abstract Among the advances in the use of geopolymer cements is their use as repair materials in concrete structures. The objective of this work was to use a geopolymer cement to repair cracks in concrete specimens, observing its mechanical performance and fracture modes. Cubic test specimens were produced and two types of cracks were evaluated as variables. Cracks were induced by steel sheets during concreting. The geopolymer cement paste and an epoxy adhesive, as reference, were used for the repairs. The results showed a 13% decrease in compressive strength for unrepaired concrete, and 3.7% in concrete repaired with geopolymer. The binder presented mechanical performance similar to that of the epoxy resin regarding crack recovery. In conclusion, repairs made with geopolymer cement are a viable and efficient means of crack recovery.

Mechanical Properties of Self-Healing System in Cementitious Material with Microcapsule

2018 ◽  
Vol 913 ◽  
pp. 1090-1096 ◽  
Author(s):  
Peng Liang ◽  
Qian Jin Mao ◽  
Zi Ming Wang ◽  
Su Ping Cui
Keyword(s):  
Particle Size ◽  
Compressive Strength ◽  
In Situ Polymerization ◽  
Urea Formaldehyde ◽  
Strength Loss ◽  
Cementitious Materials ◽  
Self Healing ◽  
Healing System ◽  
The Matrix

In this paper, several urea–formaldehyde/epoxy microcapsules with different particle sizes were synthesized by in-situ polymerization. The chemical structure and compressive rupture load of microcapsule were characterized. The effect of microcapsule dosage, particle size and preload pressure on compressive strength of cementitious materials was studied. The result shows: when the particle size of microcapsule is 2 mm~2.5 mm, the rupture load of microcapsule is highest, more than 3N; When the microcapsule dosage is less than 2.5%, the strength loss of the matrix is relatively small; With the increase of the particle size of the capsule, the strength of the matrix decrease greatly; When the dosage of microcapsule is 2.5%, the particle size is 1.5 mm and the preload pressure is 30%~45%fmax, the compressive strength of the self-healing specimen is 8% higher than that of the non-preloaded specimens, which shows a certain self-healing performance.

scholarly journals Self-Healing Concrete by Biological Substrate

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4099 ◽  
Author(s):  
How-Ji Chen ◽  
Ching-Fang Peng ◽  
Chao-Wei Tang ◽  
Yi-Tien Chen
Keyword(s):  
Calcium Carbonate ◽  
Lightweight Aggregate Concrete ◽  
White Crystal ◽  
Repair Material ◽  
Self Healing ◽  
Bacterial Strains ◽  
Calcium Carbonate Precipitation ◽  
Bacillus Pasteurii ◽  
Concrete Crack ◽  
Crack Repair

At present, the commonly used repair materials for concrete cracks mainly include epoxy systems and acrylic resins, which are all environmentally unfriendly materials, and the difference in drying shrinkage and thermal expansion often causes delamination or cracking between the original concrete matrix and the repair material. This study aimed to explore the feasibility of using microbial techniques to repair concrete cracks. The bacteria used were environmentally friendly Bacillus pasteurii. In particular, the use of lightweight aggregates as bacterial carriers in concrete can increase the chance of bacterial survival. Once the external environment meets the growth conditions of the bacteria, the vitality of the strain can be restored. Such a system can greatly improve the feasibility and success rate of bacterial mineralization in concrete. The test project included the microscopic testing of concrete crack repair, mainly to understand the crack repair effect of lightweight aggregate concrete with implanted bacterial strains, and an XRD test to confirm that the repair material was produced by the bacteria. The results show that the implanted bacterial strains can undergo Microbiologically Induced Calcium Carbonate Precipitation (MICP) and can effectively fill the cracks caused by external concrete forces by calcium carbonate deposition. According to the results on the crack profile and crack thickness, the calcium carbonate precipitate produced by the action of Bacillus pasteurii is formed by the interface between the aggregate and the cement paste, and it spreads over the entire fracture surface and then accumulates to a certain thickness to form a crack repairing effect. The analysis results of the XRD test also clearly confirm that the white crystal formed in the concrete crack is calcium carbonate. From the above test results, it is indeed feasible to use Bacillus pasteurii in the self-healing of concrete cracks.

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