The Experts below are selected from a list of 45669 Experts worldwide ranked by ideXlab platform
Nele De Belie - One of the best experts on this subject based on the ideXlab platform.
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neutron radiography based visualization and profiling of water uptake in un cracked and autonomously healed cementitious materials
Materials, 2016Co-Authors: Philip Van Den Heede, Kim Van Tittelboom, Bjorn Van Belleghem, Natalia Mariel Alderete, Nele De BelieAbstract:Given their Low Tensile Strength, cement-based materials are very susceptible to cracking. These cracks serve as preferential pathways for corrosion inducing substances. For large concrete infrastructure works, currently available time-consuming manual repair techniques are not always an option. Often, one simply cannot reach the damaged areas and when making those areas accessible anyway (e.g., by redirecting traffic), the economic impacts involved would be enormous. Under those circumstances, it might be useful to have concrete with an embedded autonomous healing mechanism. In this paper, the effectiveness of incorporating encapsulated high and Low viscosity polyurethane-based healing agents to ensure (multiple) crack healing has been investigated by means of capillary absorption tests on mortar while monitoring the time-dependent water ingress with neutron radiography. Overall visual interpretation and water front/sample cross-section area ratios as well as water profiles representing the area around the crack and their integrals do not show a preference for the high or Low viscosity healing agent. Another observation is that in presence of two cracks, only one is properly healed, especially when using the latter healing agent. Exposure to water immediately after release of the healing agent stimulates the foaming reaction of the polyurethane and ensures a better crack closure.
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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, Stijn Steuperaert, Kim Van Tittelboom, Peter Dubruel, Nele 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.
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Self-healing cementitious materials by the combination of microfibres and superabsorbent polymers
Journal of Intelligent Material Systems and Structures, 2012Co-Authors: Didier Snoeck, Stijn Steuperaert, Kim Van Tittelboom, Peter Dubruel, Nele De BelieAbstract:Concrete cracks due to its Low Tensile Strength. The presence of cracks endangers the durability as they generate a pathway for harmful particles dissolved in fluids and gases. Without a proper treatment, maintenance costs will increase. Self-healing can prevail in small cracks due to precipitation of calcium carbonate and further hydration. Therefore, the use of microfibres is proposed to control the crack width and thus to promote the self-healing efficiency. In the current research, crack sealing is also enhanced by the application of superabsorbent polymers. When cracking occurs, superabsorbent polymers are exposed to the humid environment and swell. This swelling reaction seals the crack from intruding potentially harmful substances. Mortar mixtures with microfibres and with and without superabsorbent polymers were investigated on their crack sealing and healing efficiency. Regain in mechanical properties upon crack healing was investigated by the performance of four-point-bending tests, and the seal...
Kim Van Tittelboom - One of the best experts on this subject based on the ideXlab platform.
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neutron radiography based visualization and profiling of water uptake in un cracked and autonomously healed cementitious materials
Materials, 2016Co-Authors: Philip Van Den Heede, Kim Van Tittelboom, Bjorn Van Belleghem, Natalia Mariel Alderete, Nele De BelieAbstract:Given their Low Tensile Strength, cement-based materials are very susceptible to cracking. These cracks serve as preferential pathways for corrosion inducing substances. For large concrete infrastructure works, currently available time-consuming manual repair techniques are not always an option. Often, one simply cannot reach the damaged areas and when making those areas accessible anyway (e.g., by redirecting traffic), the economic impacts involved would be enormous. Under those circumstances, it might be useful to have concrete with an embedded autonomous healing mechanism. In this paper, the effectiveness of incorporating encapsulated high and Low viscosity polyurethane-based healing agents to ensure (multiple) crack healing has been investigated by means of capillary absorption tests on mortar while monitoring the time-dependent water ingress with neutron radiography. Overall visual interpretation and water front/sample cross-section area ratios as well as water profiles representing the area around the crack and their integrals do not show a preference for the high or Low viscosity healing agent. Another observation is that in presence of two cracks, only one is properly healed, especially when using the latter healing agent. Exposure to water immediately after release of the healing agent stimulates the foaming reaction of the polyurethane and ensures a better crack closure.
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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, Stijn Steuperaert, Kim Van Tittelboom, Peter Dubruel, Nele 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.
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Self-healing cementitious materials by the combination of microfibres and superabsorbent polymers
Journal of Intelligent Material Systems and Structures, 2012Co-Authors: Didier Snoeck, Stijn Steuperaert, Kim Van Tittelboom, Peter Dubruel, Nele De BelieAbstract:Concrete cracks due to its Low Tensile Strength. The presence of cracks endangers the durability as they generate a pathway for harmful particles dissolved in fluids and gases. Without a proper treatment, maintenance costs will increase. Self-healing can prevail in small cracks due to precipitation of calcium carbonate and further hydration. Therefore, the use of microfibres is proposed to control the crack width and thus to promote the self-healing efficiency. In the current research, crack sealing is also enhanced by the application of superabsorbent polymers. When cracking occurs, superabsorbent polymers are exposed to the humid environment and swell. This swelling reaction seals the crack from intruding potentially harmful substances. Mortar mixtures with microfibres and with and without superabsorbent polymers were investigated on their crack sealing and healing efficiency. Regain in mechanical properties upon crack healing was investigated by the performance of four-point-bending tests, and the seal...
S Y Hwang - One of the best experts on this subject based on the ideXlab platform.
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mechanical properties of high Strength steel fiber reinforced concrete
Construction and Building Materials, 2004Co-Authors: P. -s. Song, S Y HwangAbstract:Abstract The marked brittleness with Low Tensile Strength and strain capacities of high-Strength concrete (HSC) can be overcome by the addition of steel fibers. This paper investigated the mechanical properties of high-Strength steel fiber-reinforced concrete. The properties included compressive and splitting Tensile Strengths, modulus of rupture, and toughness index. The steel fibers were added at the volume fractions of 0.5%, 1.0%, 1.5%, and 2.0%. The compressive Strength of the fiber-reinforced concrete reached a maximum at 1.5% volume fraction, being a 15.3% improvement over the HSC. The splitting Tensile Strength and modulus of rupture of the fiber-reinforced concrete improved with increasing the volume fraction, achieving 98.3% and 126.6% improvements, respectively, at 2.0% volume fraction. The toughness index of the fiber-reinforced concrete improved with increasing the fraction. The indexes I 5 , I 10 , and I 30 registered values of 6.5, 11.8, and 20.6, respectively, at 2.0% fraction. Strength models were established to predict the compressive and splitting Tensile Strengths and modulus of rupture of the fiber-reinforced concrete. The models give predictions matching the measurements.
N H Thom - One of the best experts on this subject based on the ideXlab platform.
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damage propagation rate and mechanical properties of recycled steel fiber reinforced and cement bound granular materials used in pavement structure
Construction and Building Materials, 2018Co-Authors: Ahmed Hilal Farhan, Andrew Dawson, N H ThomAbstract:Abstract Cement-bound granular mixtures (CBGMs) represent an attractive option to increase load-carrying capacity and sustainability in highway construction. However, reflection cracking of overlying pavement layers due to the Low Tensile Strength of CBGMs represents an important obstacle limiting their use. This study is undertaken to investigate how incorporation, in CBGMs, of recycled steel fibers extracted from old tires, at different cement levels may affect their Tensile properties related to pavement design. A combination of three levels of cement (3%, 5% and 7% by wt. of aggregate and fiber) and two reinforcement contents (0% and 0.5 by volume of aggregate) was investigated. To comprehensively quantify the benefits of fibers in the presence of variable cement contents, time-dependent fracture and damage propagation were examined quantitatively utilizing a combination of macro-surface cracks, fractal analysis and both image monitoring and processing techniques. The results indicated better Tensile Strength and toughness after cement and fiber inclusion. Furthermore, increasing the amount of cement accelerates the crack propagation and damage dispersion rate while these two parameters reduced significantly in the case of fiber-reinforced cemented aggregate. All benefits gained from fiber usage are more evident at higher cement contents.
Didier Snoeck - 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, Stijn Steuperaert, Kim Van Tittelboom, Peter Dubruel, Nele 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.
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Self-healing cementitious materials by the combination of microfibres and superabsorbent polymers
Journal of Intelligent Material Systems and Structures, 2012Co-Authors: Didier Snoeck, Stijn Steuperaert, Kim Van Tittelboom, Peter Dubruel, Nele De BelieAbstract:Concrete cracks due to its Low Tensile Strength. The presence of cracks endangers the durability as they generate a pathway for harmful particles dissolved in fluids and gases. Without a proper treatment, maintenance costs will increase. Self-healing can prevail in small cracks due to precipitation of calcium carbonate and further hydration. Therefore, the use of microfibres is proposed to control the crack width and thus to promote the self-healing efficiency. In the current research, crack sealing is also enhanced by the application of superabsorbent polymers. When cracking occurs, superabsorbent polymers are exposed to the humid environment and swell. This swelling reaction seals the crack from intruding potentially harmful substances. Mortar mixtures with microfibres and with and without superabsorbent polymers were investigated on their crack sealing and healing efficiency. Regain in mechanical properties upon crack healing was investigated by the performance of four-point-bending tests, and the seal...
