The Experts below are selected from a list of 5352 Experts worldwide ranked by ideXlab platform
Scott R. White - One of the best experts on this subject based on the ideXlab platform.
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DEVELOPMENT OF A PROTOCOL FOR MICROVASCULAR SELF-Healing
2020Co-Authors: Kathleen S. Toohey, Scott R. White, Jennifer A. Lewis, Nancy R. SottosAbstract:In a new generation of self-Healing polymers, a three dimensional microvascular network is used for storage and transport of Healing materials enabling multiple Healing cycles for a single crack. Unlike microcapsule-based self-Healing where the fluid in the capsules is consumed after Healing, the microvascular network provides a replenishable supply of Healing Agent. This Healing concept is applied to a coating-substrate system, where damage in a brittle coating containing catalyst particles is repaired by Healing Agent supplied by a microvascular network in the substrate. Under four-point bending a crack is formed in the coating which triggers the flow of Healing Agent from the microchannels into the crack plane. The Healing Agent dissolves catalyst in the coating and polymerization. The crack is reopened with additional bend tests after a rest period to determine the extent of Healing. Preliminary self-activated tests showed that multiple Healing cycles were possible with good Healing efficiency.
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Manufacture of carbon-fiber prepreg with thermoplastic/epoxy resin blends and microencapsulated solvent Healing Agents
Composites Part A-applied Science and Manufacturing, 2019Co-Authors: Nancy R. Sottos, Scott R. WhiteAbstract:Abstract Unidirectional carbon-fiber/thermoplastic/epoxy prepreg is manufactured with embedded microcapsules containing a Healing Agent for a thermoplastic-toughened epoxy matrix. A laboratory-scale prepreg fabrication line was designed to produce a prepreg fabric of which fiber-interstitial spaces accommodate microcapsules of an average diameter of 2.8 µm. Microcapsules containing the Healing Agent, ethyl phenylacetate (EPA), were coated with polydopamine (PDA) to withstand harsh manufacturing conditions. The prepreg fabrics were laminated and hot-pressed to produce composites of a high fiber volume fraction (ca. 62%), exceptional thermal stability ( T g =170 °C) and fracture toughness. The laminated composite achieved a uniform distribution of intact microcapsules with an overall concentration of 3.1 vol% and a 20 wt% thermoplastic-toughened (poly(bisphenol a-co-epichlorohydrin); PBAE) epoxy matrix developed from cure-induced phase separation. The co-existence of intact microcapsules filled with Healing Agent and the phase-separated PBAE/epoxy matrix has significant potential to mitigate small scale damage in the composite.
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A Microvascular System for the Autonomous Regeneration of Large Scale Damage in Polymeric Coatings
Advanced Engineering Materials, 2017Co-Authors: Ryan C. R. Gergely, Nancy R. Sottos, Michael N. Rossol, Sharon Tsubaki, Jonathan Wang, Scott R. WhiteAbstract:Self-Healing polymers are capable of self-repair either in response to the damage or through external stimuli, but are limited in their ability to autonomously control the volume of Healing Agents released, in the length scale of damage they address, and in their ability to respond to multiple damage events. Here, the authors report a novel design for Healing Agent storage and release for vascular coating systems that allows for complete regeneration of a coating with precise and autonomous control of coating thickness. A variety of Healing Agent formulations that cure under ambient sunlight are explored and their cure profiles and mechanical properties are reported. In the proposed vascular coating system, the stored Healing Agent remains stable within the network until large-scale damage (e.g., abrasion) completely removes the protective coating. A precise volume within the network is then released, and cures when exposed to simulated sunlight to reform the protective coating. This coating system facilitates consistent coating thickness and hardness for several cycles of coating removal and regeneration.
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Room-Temperature Polydimethylsiloxane-Based Self-Healing Polymers
Chemistry of Materials, 2012Co-Authors: Scott R. White, Paul V BraunAbstract:Polymers that respond in a productive fashion to their environment are under active development as they offer significant advantages over traditional materials. For example, polymers with the ability to self-heal and recover a significant fraction of their initial properties after being subjected to a damage event are of significant interest. Here we study the effect of Healing Agent viscosity and catalyst activity on self-Healing at and near room temperature. The viscosity of the PDMS Healing Agent was varied from 14 to 40 000 cP, and the tin-based catalysts di-n-butyltin dilaurate, dimethyl-dineodacanoate tin, di-n-butyl bis(2-ethylenehexanoate), tin II oleate, and tetrakis(acetoxydibutyl tinoxy)silane were studied. Both vinyl ester and epoxy matrices were investigated. By optimizing the viscosity of the PDMS Healing Agent and the catalytic activity, as well as selection of the appropriate adhesion promoter, a PDMS-based self-Healing system which healed at room temperature was obtained.
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performance of self Healing epoxy with microencapsulated Healing Agent and shape memory alloy wires
Polymer, 2009Co-Authors: Eva L. Kirkby, Nancy R. Sottos, Veronique Michaud, J A E Manson, Scott R. WhiteAbstract:We report the first measurements of a self-Healing polymer that combines a microencapsulated liquid Healing Agent and shape memory alloy (SMA) wires. When a propagating crack ruptures the embedded microcapsules, the liquid Healing Agent is automatically released into the crack where it contacts a solid catalyst embedded in the matrix. The SMA wires are then activated to close the crack during the Healing period. We show that dramatically improved Healing performance is obtained by the activation of embedded SMA wires. We conclude that improved Healing is due to a reduction of crack volume as a result of pulling the crack faces closed, and more complete polymerization of the Healing Agent due to the heat produced by the activated SMA wires.
Nancy R. Sottos - One of the best experts on this subject based on the ideXlab platform.
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DEVELOPMENT OF A PROTOCOL FOR MICROVASCULAR SELF-Healing
2020Co-Authors: Kathleen S. Toohey, Scott R. White, Jennifer A. Lewis, Nancy R. SottosAbstract:In a new generation of self-Healing polymers, a three dimensional microvascular network is used for storage and transport of Healing materials enabling multiple Healing cycles for a single crack. Unlike microcapsule-based self-Healing where the fluid in the capsules is consumed after Healing, the microvascular network provides a replenishable supply of Healing Agent. This Healing concept is applied to a coating-substrate system, where damage in a brittle coating containing catalyst particles is repaired by Healing Agent supplied by a microvascular network in the substrate. Under four-point bending a crack is formed in the coating which triggers the flow of Healing Agent from the microchannels into the crack plane. The Healing Agent dissolves catalyst in the coating and polymerization. The crack is reopened with additional bend tests after a rest period to determine the extent of Healing. Preliminary self-activated tests showed that multiple Healing cycles were possible with good Healing efficiency.
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Manufacture of carbon-fiber prepreg with thermoplastic/epoxy resin blends and microencapsulated solvent Healing Agents
Composites Part A-applied Science and Manufacturing, 2019Co-Authors: Nancy R. Sottos, Scott R. WhiteAbstract:Abstract Unidirectional carbon-fiber/thermoplastic/epoxy prepreg is manufactured with embedded microcapsules containing a Healing Agent for a thermoplastic-toughened epoxy matrix. A laboratory-scale prepreg fabrication line was designed to produce a prepreg fabric of which fiber-interstitial spaces accommodate microcapsules of an average diameter of 2.8 µm. Microcapsules containing the Healing Agent, ethyl phenylacetate (EPA), were coated with polydopamine (PDA) to withstand harsh manufacturing conditions. The prepreg fabrics were laminated and hot-pressed to produce composites of a high fiber volume fraction (ca. 62%), exceptional thermal stability ( T g =170 °C) and fracture toughness. The laminated composite achieved a uniform distribution of intact microcapsules with an overall concentration of 3.1 vol% and a 20 wt% thermoplastic-toughened (poly(bisphenol a-co-epichlorohydrin); PBAE) epoxy matrix developed from cure-induced phase separation. The co-existence of intact microcapsules filled with Healing Agent and the phase-separated PBAE/epoxy matrix has significant potential to mitigate small scale damage in the composite.
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A Microvascular System for the Autonomous Regeneration of Large Scale Damage in Polymeric Coatings
Advanced Engineering Materials, 2017Co-Authors: Ryan C. R. Gergely, Nancy R. Sottos, Michael N. Rossol, Sharon Tsubaki, Jonathan Wang, Scott R. WhiteAbstract:Self-Healing polymers are capable of self-repair either in response to the damage or through external stimuli, but are limited in their ability to autonomously control the volume of Healing Agents released, in the length scale of damage they address, and in their ability to respond to multiple damage events. Here, the authors report a novel design for Healing Agent storage and release for vascular coating systems that allows for complete regeneration of a coating with precise and autonomous control of coating thickness. A variety of Healing Agent formulations that cure under ambient sunlight are explored and their cure profiles and mechanical properties are reported. In the proposed vascular coating system, the stored Healing Agent remains stable within the network until large-scale damage (e.g., abrasion) completely removes the protective coating. A precise volume within the network is then released, and cures when exposed to simulated sunlight to reform the protective coating. This coating system facilitates consistent coating thickness and hardness for several cycles of coating removal and regeneration.
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performance of self Healing epoxy with microencapsulated Healing Agent and shape memory alloy wires
Polymer, 2009Co-Authors: Eva L. Kirkby, Nancy R. Sottos, Veronique Michaud, J A E Manson, Scott R. WhiteAbstract:We report the first measurements of a self-Healing polymer that combines a microencapsulated liquid Healing Agent and shape memory alloy (SMA) wires. When a propagating crack ruptures the embedded microcapsules, the liquid Healing Agent is automatically released into the crack where it contacts a solid catalyst embedded in the matrix. The SMA wires are then activated to close the crack during the Healing period. We show that dramatically improved Healing performance is obtained by the activation of embedded SMA wires. We conclude that improved Healing is due to a reduction of crack volume as a result of pulling the crack faces closed, and more complete polymerization of the Healing Agent due to the heat produced by the activated SMA wires.
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Performance of self-Healing epoxy with microencapsulated Healing Agent and shape memory alloy wires
Polymer, 2009Co-Authors: Eva L. Kirkby, Véronique J. Michaud, Nancy R. Sottos, Jan-anders E. Månson, Scott R. WhiteAbstract:We report the first measurements of a self-Healing polymer that combines a microencapsulated liquid Healing Agent and shape memory alloy (SMA) wires. When a propagating crack ruptures the embedded microcapsules, the liquid Healing Agent is automatically released into the crack where it contacts a solid catalyst embedded in the matrix. The SMA wires are then activated to close the crack during the Healing period. We show that dramatically improved Healing performance is obtained by the activation of embedded SMA wires. We conclude that improved Healing is due to a reduction of crack volume as a result of pulling the crack faces closed, and more complete polymerization of the Healing Agent due to the heat produced by the activated SMA wires. © 2009 Elsevier Ltd. All rights reserved.
Erik Schlangen - One of the best experts on this subject based on the ideXlab platform.
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Selection of Nutrient Used in Biogenic Healing Agent for Cementitious Materials
Frontiers in Materials, 2017Co-Authors: Eirini Tziviloglou, Virginie Wiktor, Henk M. Jonkers, Erik SchlangenAbstract:Biogenic self-Healing cementitious materials target on the closure of micro-cracks with precipitated inorganic minerals originating from bacterial metabolic activity. Dormant bacterial spores and organic mineral compounds often constitute a biogenic Healing Agent. The current paper focuses on the investigation of the most appropriate organic carbon source to be used as component of a biogenic Healing Agent. It is of great importance to use an appropriate organic source, since it will firstly ensure an optimal bacterial performance in terms of metabolic activity, while it should secondly affect the least the properties of the cementitious matrix. The selection is made among three different organic compounds, namely calcium lactate, calcium acetate and sodium gluconate. The methodology that was used for the research was based on continuous and non-continuous oxygen consumption measurements of washed bacterial cultures and on compressive strength tests on mortar cubes. The oxygen consumption investigation revealed a preference for calcium lactate and acetate, but an indifferent behaviour for sodium gluconate. The compressive strength on mortar cubes with different amounts of either calcium lactate or acetate (up to 2.24% per cement weight) was not or it was positively affected when the compounds were dissolved in the mixing water. In fact, for calcium lactate the increase in compressive strength reached 8%, while for calcium acetate the maximum strength increase was 13.4%.
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Bacteria-based self-Healing concrete to increase liquid tightness of cracks
Construction and Building Materials, 2016Co-Authors: Eirini Tziviloglou, Virginie Wiktor, Henk M. Jonkers, Erik SchlangenAbstract:The innovative technology of self-Healing concrete allows the material to repair the open micro-cracks that can endanger the durability of the structure, due to ingress of aggressive gasses and liquids. Various concepts of self-Healing concrete have been developed, with target on the recovery of water tightness after cracking. Among those, bacteria-based self-Healing concrete has shown promising results regarding the improvement of crack sealing performance. In this study, the bacteria-based Healing Agent is incorporated into lightweight aggregates and mixed with fresh mortar. By this means, autogenous Healing of concrete is enhanced and upon cracking the material is capable to recover water tightness. The study focuses on the investigation of the effect of Healing Agent when incorporated into the mortar matrix and the evaluation of the recovery of liquid tightness after cracking and exposure to two different Healing regimes (water immersion and wet-dry cycles) through water permeability tests. It was found that the compressive strength of the mortar containing lightweight aggregates is not affected by the presence of the Healing Agent. The study also reveals that the recovery of water tightness does not differ substantially either for specimens with or without Healing Agent when immersed continuously in water. Conversely, the recovery of water tightness increases significantly for specimens containing the Healing Agent compared to specimens without it, when subjected to wet-dry cycles. Oxygen concentration measurements and bacterial traces on calcite formations confirmed the bacterial activity on specimens containing the Healing Agent.
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Preparation and optimization of bio-based and light weight aggregate-based Healing Agent for application in concrete
2015Co-Authors: Eirini Tziviloglou, Virginie Wiktor, Henk M. Jonkers, Erik SchlangenAbstract:The innovative technology of self-Healing concrete allows the material to repair the open micro-cracks that can endanger the structure’s durability, due to ingress of aggressive liquids. Various concepts of self-Healing concrete use encapsulation techniques, in order to immobilize and protect the Healing Agent during mixing and setting. In this paper the bio-based Healing Agent, consisting of alkaliphilic bacterial spores and organic mineral compounds (feed), is encapsulated into light weight aggregates (LWA). Although, the concept of shielding the Healing Agent in LWA capsules is simple and effective, there are some challenges regarding the incorporation procedure. In this study a method for efficient incorporation of Healing Agent into the LWA is developed. The results obtained in the current study show that the optimized method increases considerably the amount of Healing Agent embedded into LWA, in comparison with what was achieved in a previous study. As a consequence, the LWA treated with the new incorporation procedure are likely to provide better crack sealing and therefore enhanced durability protection for concrete.
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Chloride Transport under Compressive Load in Bacteria-based Self- Healing Concrete
5th Int. Conf. Self-Healing Mater., 2015Co-Authors: M Y Balqis, Erik Schlangen, Henk M. JonkersAbstract:An experiment was carried out in this study to investigate the effect of compressive load on chloride penetration in self-Healing concrete containing bacterial-based Healing Agent. Bacteria-based Healing Agent with the fraction of 2 mm – 4 mm of particles sizes were used in this contribution. ESEM was applied to study samples which were taken by cutting the area of prisms in contact with the chloride solution and together with LIBS method to measure the total chloride content of bacterial concrete. Three load parameters of the compressive load are proposed to describe the phenomena of chloride transportation in bacterial concrete by which the results in prediction analysis of concrete performance within service life were much affected by different percentage of mechanical damage. It was found that the particles sizes of Healing Agent used leads to more porous-structure of concrete, subsequently affect the transport rate of chloride in concrete. Nevertheless, this investigation indicates that bacteria-based Healing Agent can still be considered as a measure of protection to concrete under combined action.
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application of bacteria as self Healing Agent for the development of sustainable concrete
Ecological Engineering, 2010Co-Authors: Henk M. Jonkers, Arjan Thijssen, Oğuzhan Çopuroğlu, Gerard Muyzer, Erik SchlangenAbstract:Abstract The application of concrete is rapidly increasing worldwide and therefore the development of sustainable concrete is urgently needed for environmental reasons. As presently about 7% of the total anthropogenic atmospheric CO 2 emission is due to cement production, mechanisms that would contribute to a longer service life of concrete structures would make the material not only more durable but also more sustainable. One such mechanism that receives increasing attention in recent years is the ability for self-repair, i.e. the autonomous Healing of cracks in concrete. In this study we investigated the potential of bacteria to act as self-Healing Agent in concrete, i.e. their ability to repair occurring cracks. A specific group of alkali-resistant spore-forming bacteria related to the genus Bacillus was selected for this purpose. Bacterial spores directly added to the cement paste mixture remained viable for a period up to 4 months. A continuous decrease in pore size diameter during cement stone setting probably limited life span of spores as pore widths decreased below 1 μm, the typical size of Bacillus spores. However, as bacterial cement stone specimens appeared to produce substantially more crack-plugging minerals than control specimens, the potential application of bacterial spores as self-Healing Agent appears promising.
Eva L. Kirkby - One of the best experts on this subject based on the ideXlab platform.
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performance of self Healing epoxy with microencapsulated Healing Agent and shape memory alloy wires
Polymer, 2009Co-Authors: Eva L. Kirkby, Nancy R. Sottos, Veronique Michaud, J A E Manson, Scott R. WhiteAbstract:We report the first measurements of a self-Healing polymer that combines a microencapsulated liquid Healing Agent and shape memory alloy (SMA) wires. When a propagating crack ruptures the embedded microcapsules, the liquid Healing Agent is automatically released into the crack where it contacts a solid catalyst embedded in the matrix. The SMA wires are then activated to close the crack during the Healing period. We show that dramatically improved Healing performance is obtained by the activation of embedded SMA wires. We conclude that improved Healing is due to a reduction of crack volume as a result of pulling the crack faces closed, and more complete polymerization of the Healing Agent due to the heat produced by the activated SMA wires.
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Performance of self-Healing epoxy with microencapsulated Healing Agent and shape memory alloy wires
Polymer, 2009Co-Authors: Eva L. Kirkby, Véronique J. Michaud, Nancy R. Sottos, Jan-anders E. Månson, Scott R. WhiteAbstract:We report the first measurements of a self-Healing polymer that combines a microencapsulated liquid Healing Agent and shape memory alloy (SMA) wires. When a propagating crack ruptures the embedded microcapsules, the liquid Healing Agent is automatically released into the crack where it contacts a solid catalyst embedded in the matrix. The SMA wires are then activated to close the crack during the Healing period. We show that dramatically improved Healing performance is obtained by the activation of embedded SMA wires. We conclude that improved Healing is due to a reduction of crack volume as a result of pulling the crack faces closed, and more complete polymerization of the Healing Agent due to the heat produced by the activated SMA wires. © 2009 Elsevier Ltd. All rights reserved.
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Embedded shape-memory alloy wires for improved performance of self-Healing polymers
Advanced Functional Materials, 2008Co-Authors: Eva L. Kirkby, Joseph D. Rule, Scott R. White, Nancy R. Sottos, Veronique Michaud, Jan-anders E. MånsonAbstract:We report the first measurements of self-Healing polymers with embedded shape-memory alloy (SMA) wires. The addition of SMA wires shows improvements of healed peak fracture loads by up to a factor of 1.6, approaching the performance of the virgin material. Moreover, the repairs can be achieved with reduced amounts of Healing Agent. The improvements in performance are due to two main effects: (i) crack closure, which reduces the total crack volume and increases the crack fill factor for a given amount of Healing Agent and (ii) heating of the Healing Agent during polymerization, which increases the degree of cure of the polymerized Healing Agent.
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Embedded shape-memory alloy wires for improved performance of self-Healing polymers
Advanced Functional Materials, 2008Co-Authors: Eva L. Kirkby, Véronique J. Michaud, Joseph D. Rule, Scott R. White, Nancy R. Sottos, Veronique Michaud, Jan-anders E. MånsonAbstract:We report the first measurements of self-Healing polymers with embedded shape-memory alloy (SMA) wires. The addition of SMA wires shows improvements of healed peak fracture loads by up to a factor of 1.6, approaching the performance of the virgin material. Moreover, the repairs can be achieved with reduced amounts of Healing Agent. The improvements in performance are due to two main effects: (i) crack closure, which reduces the total crack volume and increases the crack fill factor for a given amount of Healing Agent and (ii) heating of the Healing Agent during polymerization, which increases the degree of cure of the polymerized Healing Agent. © 2008 WILEY-VCH Verlag GmbH and . Co. KGaA.
Henk M. Jonkers - One of the best experts on this subject based on the ideXlab platform.
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Selection of Nutrient Used in Biogenic Healing Agent for Cementitious Materials
Frontiers in Materials, 2017Co-Authors: Eirini Tziviloglou, Virginie Wiktor, Henk M. Jonkers, Erik SchlangenAbstract:Biogenic self-Healing cementitious materials target on the closure of micro-cracks with precipitated inorganic minerals originating from bacterial metabolic activity. Dormant bacterial spores and organic mineral compounds often constitute a biogenic Healing Agent. The current paper focuses on the investigation of the most appropriate organic carbon source to be used as component of a biogenic Healing Agent. It is of great importance to use an appropriate organic source, since it will firstly ensure an optimal bacterial performance in terms of metabolic activity, while it should secondly affect the least the properties of the cementitious matrix. The selection is made among three different organic compounds, namely calcium lactate, calcium acetate and sodium gluconate. The methodology that was used for the research was based on continuous and non-continuous oxygen consumption measurements of washed bacterial cultures and on compressive strength tests on mortar cubes. The oxygen consumption investigation revealed a preference for calcium lactate and acetate, but an indifferent behaviour for sodium gluconate. The compressive strength on mortar cubes with different amounts of either calcium lactate or acetate (up to 2.24% per cement weight) was not or it was positively affected when the compounds were dissolved in the mixing water. In fact, for calcium lactate the increase in compressive strength reached 8%, while for calcium acetate the maximum strength increase was 13.4%.
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Bacteria-based self-Healing concrete to increase liquid tightness of cracks
Construction and Building Materials, 2016Co-Authors: Eirini Tziviloglou, Virginie Wiktor, Henk M. Jonkers, Erik SchlangenAbstract:The innovative technology of self-Healing concrete allows the material to repair the open micro-cracks that can endanger the durability of the structure, due to ingress of aggressive gasses and liquids. Various concepts of self-Healing concrete have been developed, with target on the recovery of water tightness after cracking. Among those, bacteria-based self-Healing concrete has shown promising results regarding the improvement of crack sealing performance. In this study, the bacteria-based Healing Agent is incorporated into lightweight aggregates and mixed with fresh mortar. By this means, autogenous Healing of concrete is enhanced and upon cracking the material is capable to recover water tightness. The study focuses on the investigation of the effect of Healing Agent when incorporated into the mortar matrix and the evaluation of the recovery of liquid tightness after cracking and exposure to two different Healing regimes (water immersion and wet-dry cycles) through water permeability tests. It was found that the compressive strength of the mortar containing lightweight aggregates is not affected by the presence of the Healing Agent. The study also reveals that the recovery of water tightness does not differ substantially either for specimens with or without Healing Agent when immersed continuously in water. Conversely, the recovery of water tightness increases significantly for specimens containing the Healing Agent compared to specimens without it, when subjected to wet-dry cycles. Oxygen concentration measurements and bacterial traces on calcite formations confirmed the bacterial activity on specimens containing the Healing Agent.
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Preparation and optimization of bio-based and light weight aggregate-based Healing Agent for application in concrete
2015Co-Authors: Eirini Tziviloglou, Virginie Wiktor, Henk M. Jonkers, Erik SchlangenAbstract:The innovative technology of self-Healing concrete allows the material to repair the open micro-cracks that can endanger the structure’s durability, due to ingress of aggressive liquids. Various concepts of self-Healing concrete use encapsulation techniques, in order to immobilize and protect the Healing Agent during mixing and setting. In this paper the bio-based Healing Agent, consisting of alkaliphilic bacterial spores and organic mineral compounds (feed), is encapsulated into light weight aggregates (LWA). Although, the concept of shielding the Healing Agent in LWA capsules is simple and effective, there are some challenges regarding the incorporation procedure. In this study a method for efficient incorporation of Healing Agent into the LWA is developed. The results obtained in the current study show that the optimized method increases considerably the amount of Healing Agent embedded into LWA, in comparison with what was achieved in a previous study. As a consequence, the LWA treated with the new incorporation procedure are likely to provide better crack sealing and therefore enhanced durability protection for concrete.
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Chloride Transport under Compressive Load in Bacteria-based Self- Healing Concrete
5th Int. Conf. Self-Healing Mater., 2015Co-Authors: M Y Balqis, Erik Schlangen, Henk M. JonkersAbstract:An experiment was carried out in this study to investigate the effect of compressive load on chloride penetration in self-Healing concrete containing bacterial-based Healing Agent. Bacteria-based Healing Agent with the fraction of 2 mm – 4 mm of particles sizes were used in this contribution. ESEM was applied to study samples which were taken by cutting the area of prisms in contact with the chloride solution and together with LIBS method to measure the total chloride content of bacterial concrete. Three load parameters of the compressive load are proposed to describe the phenomena of chloride transportation in bacterial concrete by which the results in prediction analysis of concrete performance within service life were much affected by different percentage of mechanical damage. It was found that the particles sizes of Healing Agent used leads to more porous-structure of concrete, subsequently affect the transport rate of chloride in concrete. Nevertheless, this investigation indicates that bacteria-based Healing Agent can still be considered as a measure of protection to concrete under combined action.
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Potential of bacteria-based repair solution as Healing Agent for porous network concrete
2013Co-Authors: Virginie Wiktor, Henk M. Jonkers, Senot Sangadji, H.e.j.g. SchlangenAbstract:Bacterially induced calcium carbonate precipitation has received considerable attention for its potential application in enforcing or repairing construction material. The mechanism of bacterially mediated calcite precipitation in those studies is primarily based on the enzymatic hydrolysis of urea. Besides calcite precipitation, this reaction mechanism leads also to the production of ammonium ions which may result in excessive environmental pressure. More recently, bacterially mediated calcite precipitation thanks to metabolic conversion of calcium lactate has been successfully applied in self-Healing concrete. This concept is also now considered for the development of bio-based repair system for concrete structures. The bio-based repair system as presented in this paper is a liquid-based system which transports the bio-based Agent into concrete. This paper presents the recent advances on the development of the bacteria-based repair system and especially its possible application as Healing Agent in porous network concrete. To assess the repair capacity of the system the bacteria-based solution is injected into porous cores, and the production of the biomineral in time is monitored by X-ray micro-tomography. In parallel, water permeability testing is conducted before and after the injection of the bacteria-based solution to determine the sealing efficiency of the system. The precipitate is analyzed with FTIR and thermal analysis for identification and quantification. Finally, at the end of the Healing period, polished sections of injected specimens are observed with ESEM/EDS to analyze and locate precipitated biominerals. FTIR results coupled with thermal analysis and ESEM observations showed that CaCO3 has been formed in pores after 21 days, with increased amount after 28 days. Moreover, the evidence that CaCO3 precipitation was indeed mediated by bacteria has been found with observations of bacteria imprints on Ca-based minerals. It can be concluded that the bacteria-based repair system can successfully be injected as Healing Agent into porous network concrete.
