Constraints on CaCO3 precipitation in superabsorbent polymer by aerobic bacteria

Nielsen, Søren Dollerup; Koren, Klaus; Löbmann, Korbinian; Hinge, Mogens; Scoma, Alberto; Kjeldsen, Kasper Urup; Røy, Hans

doi:10.1007/s00253-019-10215-4

Cited by 21 publications

(9 citation statements)

References 39 publications

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“…Different carriers for immobilization of bacteria have been used, such as clay aggregates, perlite, microcapsules, and super absorbent polymers. 245,[251][252][253][254] For example, spore-forming B. subtilis was genetically transformed with a biosilicification gene, BKH2, and incorporated in concrete/mortar matrices. The matrices were subjected to loads to create micro/macroscopic cracks and then immersed in growth media to start the healing process.…”

Section: Other Applications Of Stimuli-responsive Elmsmentioning

confidence: 99%

Stimuli-responsive engineered living materials

2021

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Section: Other Applications Of Stimuli-responsive Elmsmentioning

confidence: 99%

Stimuli-responsive engineered living materials

2021

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“…B. alkalinitrilicus endospores were produced on modified Schaeffer’s medium and encapsulated in an acrylamide polymer cross-linked with bis-acrylamide to give superabsorbent properties. 41 The endospore amended SAPs were freeze-dried until all water had sublimated and ground to <0.5 mm diameter particles in an agate mortar. The SAP particles were placed inside the entire length of the cracks of the well cement specimens with sterile tweezers.…”

Section: Methodsmentioning

confidence: 99%

Optical Sensing of pH and O₂ in the Evaluation of Bioactive Self-Healing Cement

Nielsen¹,

Paegle

Borisov

et al. 2019

ACS Omega

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Leakage from cementitious structures with a retaining function can have devastating environmental consequences. Leaks can originate from cracks within the hardened cementitious material that is supposed to seal the structure off from the surrounding environment. Bioactive self-healing concretes containing bacteria capable of microbially inducing CaCO3 precipitation have been suggested to mitigate the healing of such cracks before leaking occurs. An important parameter determining the biocompatibility of concretes and cements is the pH environment. Therefore, a novel ratiometric pH optode imaging system based on an inexpensive single-lens reflex (SLR) camera was used to characterize the pH of porewater within cracks of submerged hydrated oil and gas well cement. This enabled the imaging of pH with a spatial distribution in high resolution (50 μm per pixel) and a gradient of 1.4 pH units per 1 mm. The effect of fly ash substitution and hydration time on the pH of the cement surface was evaluated by this approach. The results show that pH is significantly reduced from pH >11 to below 10 with increasing fly ash content as well as hydration time. The assessment of bioactivity in the cement was evaluated by introducing superabsorbent polymers with encapsulated Bacillus alkalinitrilicus endospores into the cracks. The bacterial activity was measured using oxygen optodes, which showed the highest bacterial activity with increasing amounts of fly ash substitution in the cement, correlating with the decrease in the pH. Overall, our results demonstrate that the pH of well cements can be reliably measured and modified to sustain the microbial activity.

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“…Activation (germination) of the applied alkaliphilic bacterial spores occurs in pH range from 8 to 11.5 [2]. As the pH of the concrete mix during preparation and casting is well above 11.5, activation of the spores does not occur at this stage but only when pH drops below 11.5 due to external water that ingress cracks [24].…”

Section: Development Of Bacteria-based Self-healing Agentmentioning

confidence: 99%

Bacteria-based self-healing concrete: evaluation of full scale demonstrator projects

Mors¹,

Jonkers

2020

RILEM Tech Lett

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Bacteria-based self-healing concrete is an innovative concrete that contains a self-healing agent that provides the material with enhanced autonomous crack-sealing performance. A specific type of this concrete, based on a healing agent composed of bacterial spores and lactate as carbon source, has been developed and applied by the Delft University of Technology for over ten years. Under laboratory conditions it was proven that, depending on the dosage of healing agent, self-healing of cracks up to 0.8 mm widths occurs. As such the material potentially allows reduction of steel reinforcement used for crack width limitation in watertight constructions. Application of self-healing concrete would therefore not only result in a reduction of costs but also in improvement of environmental performance (lower CO2 footprint) and ease of in situ casting due to reduction of use of steel in waterproof applications. However, according to the EN 1990 Eurocode (Basis of structural design), customary application of a novel type of concrete must be preceded by full scale demonstrators proving evidence for safe and functional performance. In this contribution we portray full scale application of bacteria-based self-healing agent as developed by the Delft research group in two repair mortar-and in two concrete construction demonstrator projects. These demonstrator projects show that addition of the bacteria-based self-healing agent to the concrete mix is safe as no negative side effects on construction performance was observed. However, it also proved difficult to find evidence for increased crack-healing performance as cracking in the demonstrator constructions hardly occurred. In further full scale demonstrators we therefore plan to drastically reduce amount of crack width-restraining reinforcement to show crackhealing capacity and potential to save on use of reinforcement steel in watertight concrete constructions.

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Constraints on CaCO3 precipitation in superabsorbent polymer by aerobic bacteria

Cited by 21 publications

References 39 publications

Stimuli-responsive engineered living materials

Stimuli-responsive engineered living materials

Optical Sensing of pH and O₂ in the Evaluation of Bioactive Self-Healing Cement

Bacteria-based self-healing concrete: evaluation of full scale demonstrator projects

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Constraints on CaCO3 precipitation in superabsorbent polymer by aerobic bacteria

Cited by 21 publications

References 39 publications

Stimuli-responsive engineered living materials

Stimuli-responsive engineered living materials

Optical Sensing of pH and O2 in the Evaluation of Bioactive Self-Healing Cement

Bacteria-based self-healing concrete: evaluation of full scale demonstrator projects

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Product

Resources

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Optical Sensing of pH and O₂ in the Evaluation of Bioactive Self-Healing Cement