The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Didier Snoeck - One of the best experts on this subject based on the ideXlab platform.
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Crack Mitigation in Concrete: Superabsorbent Polymers as Key to Success?
Materials, 2017Co-Authors: Arn Mignon, Didier Snoeck, Peter Dubruel, Sandra Van Vlierberghe, Nele De BelieAbstract:Cracking is a major concern in building applications. Cracks may arise from shrinkage, freeze/thawing and/or structural stresses, amongst others. Several solutions can be found but superabsorbent polymers (SAPs) seem to be interesting to counteract these problems. At an early age, the absorbed Water by the SAPs may be used to mitigate autogenous and plastic shrinkage. The formed macro pores may increase the freeze/thaw resistance. The swelling upon Water ingress may seal a crack from intruding fluids and may regain the overall Water-Tightness. The latter Water may promote autogenous healing. The use of superabsorbent polymers is thus very interesting. This review paper summarizes the current research and gives a critical note towards the use of superabsorbent polymers in cementitious materials.
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The use of superabsorbent polymers as a crack sealing and crack healing mechanism in cementitious materials
2012Co-Authors: Didier Snoeck, Nele De Belie, Stijn Steuperaert, Kim Van Tittelboom, Peter DubruelAbstract:As concrete cracks due to its low tensile strength and as harmful fluids may migrate into these cracks, the durability of concrete is endangered if no proper treatment or manual repair is applied. To address this need, this research focusses on the use of superabsorbent polymers (1) to seal cracks from intruding potentially harmful substances and (2) to heal the crack due to further hydration and precipitation of calcium carbonate. The first focus relies on hindering the fluid flow by swelling of superabsorbent polymers after they are exposed to a humid environment. The sealing capacity was measured by means of Water permeability tests and through visualization of permeability tests by neutron radiography. Superabsorbent polymers are able to seal cracks and thus allow a recovery in Water-Tightness as a decrease in permeability is noticed. The second focus relies on healing of small cracks in fibre reinforced cementitious materials, restoring the mechanical properties. The regain in mechanical properties was analyzed by four-point-bending tests and the crack closure was microscopically monitored. Cracks close through the combination of further hydration of unhydrated cement particles, precipitation of calcium carbonate and activation of the pozzolanic reaction of fly ash. Desorption of superabsorbent polymers triggers healing in the vicinity of crack faces and cracks up to 130 μm were able to close completely in wet/dry cycles due to the precipitation of calcium carbonate. Mortar samples containing superabsorbent polymers even showed partial healing when stored under a relative humidity of more than 60%. In this way, a smart cementitious material which is reliable and independent from the conditions is acquired.
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visualization of Water penetration in cementitious materials with superabsorbent polymers by means of neutron radiography
Cement and Concrete Research, 2012Co-Authors: Didier Snoeck, Peter Dubruel, Stijn Steuperaert, K Van Tittelboom, N De BelieAbstract:Concrete cracks due to its low tensile strength. As both harmful gases and fluids may enter the concrete by migrating into cracks, the durability is endangered. The service life decreases, repair costs rise and buildings could structurally decline. In the current research, crack sealing is enhanced by the use of superabsorbent polymers (SAP). When cracking occurs, SAP particles are exposed to the humid environment and swell, sealing the crack. By means of neutron radiography, the moisture distribution is studied during capillary absorption and Water permeability tests. Capillary absorption in a crack and Water permeability through a crack are reduced in specimens containing SAP particles. SAP particles are able to seal the crack, thus allowing a recovery of the Water-Tightness of the structure. The total uptake of potentially harmful substances hereby lowers, leading to an enhanced long-term durability and lower maintenance costs.
Peter Dubruel - One of the best experts on this subject based on the ideXlab platform.
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Crack Mitigation in Concrete: Superabsorbent Polymers as Key to Success?
Materials, 2017Co-Authors: Arn Mignon, Didier Snoeck, Peter Dubruel, Sandra Van Vlierberghe, Nele De BelieAbstract:Cracking is a major concern in building applications. Cracks may arise from shrinkage, freeze/thawing and/or structural stresses, amongst others. Several solutions can be found but superabsorbent polymers (SAPs) seem to be interesting to counteract these problems. At an early age, the absorbed Water by the SAPs may be used to mitigate autogenous and plastic shrinkage. The formed macro pores may increase the freeze/thaw resistance. The swelling upon Water ingress may seal a crack from intruding fluids and may regain the overall Water-Tightness. The latter Water may promote autogenous healing. The use of superabsorbent polymers is thus very interesting. This review paper summarizes the current research and gives a critical note towards the use of superabsorbent polymers in cementitious materials.
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The use of superabsorbent polymers as a crack sealing and crack healing mechanism in cementitious materials
2012Co-Authors: Didier Snoeck, Nele De Belie, Stijn Steuperaert, Kim Van Tittelboom, Peter DubruelAbstract:As concrete cracks due to its low tensile strength and as harmful fluids may migrate into these cracks, the durability of concrete is endangered if no proper treatment or manual repair is applied. To address this need, this research focusses on the use of superabsorbent polymers (1) to seal cracks from intruding potentially harmful substances and (2) to heal the crack due to further hydration and precipitation of calcium carbonate. The first focus relies on hindering the fluid flow by swelling of superabsorbent polymers after they are exposed to a humid environment. The sealing capacity was measured by means of Water permeability tests and through visualization of permeability tests by neutron radiography. Superabsorbent polymers are able to seal cracks and thus allow a recovery in Water-Tightness as a decrease in permeability is noticed. The second focus relies on healing of small cracks in fibre reinforced cementitious materials, restoring the mechanical properties. The regain in mechanical properties was analyzed by four-point-bending tests and the crack closure was microscopically monitored. Cracks close through the combination of further hydration of unhydrated cement particles, precipitation of calcium carbonate and activation of the pozzolanic reaction of fly ash. Desorption of superabsorbent polymers triggers healing in the vicinity of crack faces and cracks up to 130 μm were able to close completely in wet/dry cycles due to the precipitation of calcium carbonate. Mortar samples containing superabsorbent polymers even showed partial healing when stored under a relative humidity of more than 60%. In this way, a smart cementitious material which is reliable and independent from the conditions is acquired.
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visualization of Water penetration in cementitious materials with superabsorbent polymers by means of neutron radiography
Cement and Concrete Research, 2012Co-Authors: Didier Snoeck, Peter Dubruel, Stijn Steuperaert, K Van Tittelboom, N De BelieAbstract:Concrete cracks due to its low tensile strength. As both harmful gases and fluids may enter the concrete by migrating into cracks, the durability is endangered. The service life decreases, repair costs rise and buildings could structurally decline. In the current research, crack sealing is enhanced by the use of superabsorbent polymers (SAP). When cracking occurs, SAP particles are exposed to the humid environment and swell, sealing the crack. By means of neutron radiography, the moisture distribution is studied during capillary absorption and Water permeability tests. Capillary absorption in a crack and Water permeability through a crack are reduced in specimens containing SAP particles. SAP particles are able to seal the crack, thus allowing a recovery of the Water-Tightness of the structure. The total uptake of potentially harmful substances hereby lowers, leading to an enhanced long-term durability and lower maintenance costs.
Henk M. Jonkers - One of the best experts on this subject based on the ideXlab platform.
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Feasibility of lactate derivative based agent as additive for concrete for regain of crack Water Tightness by bacterial metabolism
Industrial Crops and Products, 2017Co-Authors: R.m. Mors, Henk M. JonkersAbstract:Abstract Lactate, produced by fermentation of e.g. cane or corn residues, can serve as a carbon source in bacterial healing for cement-based materials such as concrete. Bacterial spores, activation nutrients and a carbon source are mixed in with dry concrete or mortar constituents upon material production. Upon cracking of the concrete matrix and ingress of Water, an active bacterial colony forms and starts to convert the included carbon source to CO 2 . In the alkaline surrounding of concrete carbonates form and deposit as minerals on the crack surface, sealing the entrance to further ingress. In this work a lactate derivative based healing agent containing bacteria and activation nutrients is added to a commercial mortar, exerting negligible effect on the mortar strength development. Functionality of the agent is indicated by oxygen consumption under aerobic conditions and shown by regain of crack Water Tightness beyond the autogenous healing capacity in a permeability test. In order to indicate feasibility for healing agent application in a commercial setting, the environmental burden is discussed and a competitive production price is estimated.
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Effect on Concrete Surface Water Absorption upon Addition of Lactate Derived Agent
THE Coatings, 2017Co-Authors: R.m. Mors, Henk M. JonkersAbstract:Water Tightness of a concrete cover layer is important, as it is typically used as a protective coating of the steel reinforcement. Water Tightness can be impaired by crack formation or by permeability. A bacteria-based lactate-derived healing agent (HA) can be added to concrete to enhance the potential for restoration of Water Tightness. Bacterial conversion of the included carbon source results in CO2 production and subsequent CaCO3 precipitation, similar to the mechanism of concrete carbonation. Carbonation is known to densify concrete, particularly when using ordinary Portland cement (OPC), but to a much lower extend in slag-based concrete (CEM III/B). To identify the effect of HA addition on concrete properties, this study focusses on the ingress of moisture in non-cracked concrete surfaces by assessing capillary Water absorption. Surface properties were determined for sealed and unsealed surfaces of concrete—either based on OPC or CEM III/B—before and after curing under three different conditions: Dry, wet, or humid. HA addition to concrete containing slag cement generated a surface less prone to continued drying, but resulted in higher Water absorption. In contrast, surface Water absorption significantly decreased upon HA addition to OPC-based samples, independent of the curing regime. It is therefore concluded that HA in its current form is suitable for application in OPC, but less in CEM III/B-based mixtures.
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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.
Erik Schlangen - One of the best experts on this subject based on the ideXlab platform.
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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.
N De Belie - One of the best experts on this subject based on the ideXlab platform.
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visualization of Water penetration in cementitious materials with superabsorbent polymers by means of neutron radiography
Cement and Concrete Research, 2012Co-Authors: Didier Snoeck, Peter Dubruel, Stijn Steuperaert, K Van Tittelboom, N De BelieAbstract:Concrete cracks due to its low tensile strength. As both harmful gases and fluids may enter the concrete by migrating into cracks, the durability is endangered. The service life decreases, repair costs rise and buildings could structurally decline. In the current research, crack sealing is enhanced by the use of superabsorbent polymers (SAP). When cracking occurs, SAP particles are exposed to the humid environment and swell, sealing the crack. By means of neutron radiography, the moisture distribution is studied during capillary absorption and Water permeability tests. Capillary absorption in a crack and Water permeability through a crack are reduced in specimens containing SAP particles. SAP particles are able to seal the crack, thus allowing a recovery of the Water-Tightness of the structure. The total uptake of potentially harmful substances hereby lowers, leading to an enhanced long-term durability and lower maintenance costs.
