The Experts below are selected from a list of 3297 Experts worldwide ranked by ideXlab platform
Athanasios I Karabinis - One of the best experts on this subject based on the ideXlab platform.
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effect of patch Repair and strengthening with ebr and nsm cfrp laminates for rc beams with low medium and heavy corrosion
Composites Part B-engineering, 2018Co-Authors: Garyfalia G Triantafyllou, Theodoros C Rousakis, Athanasios I KarabinisAbstract:Abstract The experimental results on the effectiveness of patch Repair and FRP bonded laminates to retrofit reinforced concrete beams with corrosion damage are discussed in this paper. The uncovering of the damaged concrete cover provides a more accurate assessment of the corrosion degree, as the actual mass loss of reinforcement can be better calibrated. The mass loss of the tensile reinforcement varied at approximately 7.5%–24%. The necessity of the removal of the cracked concrete substrate, treatment of corroded reinforcement and Repair by patching with a polymer modified Mortar is highlighted. Two different strengthening techniques are implemented, of externally bonded EBR or NSM Carbon FRP laminates, having equivalent axial rigidity. CFRP wraps were also applied for shear strengthening to replace corroded stirrups. The load-deflection curves showed that the effect of corrosion on load bearing capacity and bond between the concrete and steel was detrimental for high mass losses. A satisfactory force transfer through the old and patch Repaired concrete and through Repair Mortar and CFRP reinforcement interface was noted. The shear strengthening not only prevented the debonding of the EB laminate at the end but also improved the bond performance between the laminate and concrete, especially for the high corroded beam.
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effect of patch Repair and strengthening with ebr and nsm cfrp laminates for rc beams with low medium and heavy corrosion
Composites Part B-engineering, 2018Co-Authors: Garyfalia G Triantafyllou, Theodoros C Rousakis, Athanasios I KarabinisAbstract:Abstract The experimental results on the effectiveness of patch Repair and FRP bonded laminates to retrofit reinforced concrete beams with corrosion damage are discussed in this paper. The uncovering of the damaged concrete cover provides a more accurate assessment of the corrosion degree, as the actual mass loss of reinforcement can be better calibrated. The mass loss of the tensile reinforcement varied at approximately 7.5%–24%. The necessity of the removal of the cracked concrete substrate, treatment of corroded reinforcement and Repair by patching with a polymer modified Mortar is highlighted. Two different strengthening techniques are implemented, of externally bonded EBR or NSM Carbon FRP laminates, having equivalent axial rigidity. CFRP wraps were also applied for shear strengthening to replace corroded stirrups. The load-deflection curves showed that the effect of corrosion on load bearing capacity and bond between the concrete and steel was detrimental for high mass losses. A satisfactory force transfer through the old and patch Repaired concrete and through Repair Mortar and CFRP reinforcement interface was noted. The shear strengthening not only prevented the debonding of the EB laminate at the end but also improved the bond performance between the laminate and concrete, especially for the high corroded beam.
Garyfalia G Triantafyllou - One of the best experts on this subject based on the ideXlab platform.
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effect of patch Repair and strengthening with ebr and nsm cfrp laminates for rc beams with low medium and heavy corrosion
Composites Part B-engineering, 2018Co-Authors: Garyfalia G Triantafyllou, Theodoros C Rousakis, Athanasios I KarabinisAbstract:Abstract The experimental results on the effectiveness of patch Repair and FRP bonded laminates to retrofit reinforced concrete beams with corrosion damage are discussed in this paper. The uncovering of the damaged concrete cover provides a more accurate assessment of the corrosion degree, as the actual mass loss of reinforcement can be better calibrated. The mass loss of the tensile reinforcement varied at approximately 7.5%–24%. The necessity of the removal of the cracked concrete substrate, treatment of corroded reinforcement and Repair by patching with a polymer modified Mortar is highlighted. Two different strengthening techniques are implemented, of externally bonded EBR or NSM Carbon FRP laminates, having equivalent axial rigidity. CFRP wraps were also applied for shear strengthening to replace corroded stirrups. The load-deflection curves showed that the effect of corrosion on load bearing capacity and bond between the concrete and steel was detrimental for high mass losses. A satisfactory force transfer through the old and patch Repaired concrete and through Repair Mortar and CFRP reinforcement interface was noted. The shear strengthening not only prevented the debonding of the EB laminate at the end but also improved the bond performance between the laminate and concrete, especially for the high corroded beam.
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effect of patch Repair and strengthening with ebr and nsm cfrp laminates for rc beams with low medium and heavy corrosion
Composites Part B-engineering, 2018Co-Authors: Garyfalia G Triantafyllou, Theodoros C Rousakis, Athanasios I KarabinisAbstract:Abstract The experimental results on the effectiveness of patch Repair and FRP bonded laminates to retrofit reinforced concrete beams with corrosion damage are discussed in this paper. The uncovering of the damaged concrete cover provides a more accurate assessment of the corrosion degree, as the actual mass loss of reinforcement can be better calibrated. The mass loss of the tensile reinforcement varied at approximately 7.5%–24%. The necessity of the removal of the cracked concrete substrate, treatment of corroded reinforcement and Repair by patching with a polymer modified Mortar is highlighted. Two different strengthening techniques are implemented, of externally bonded EBR or NSM Carbon FRP laminates, having equivalent axial rigidity. CFRP wraps were also applied for shear strengthening to replace corroded stirrups. The load-deflection curves showed that the effect of corrosion on load bearing capacity and bond between the concrete and steel was detrimental for high mass losses. A satisfactory force transfer through the old and patch Repaired concrete and through Repair Mortar and CFRP reinforcement interface was noted. The shear strengthening not only prevented the debonding of the EB laminate at the end but also improved the bond performance between the laminate and concrete, especially for the high corroded beam.
Nemkumar Banthia - One of the best experts on this subject based on the ideXlab platform.
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moisture transport and steel rebar corrosion in Repair composites incorporating nano fibrillated cellulose nfc
Construction and Building Materials, 2021Co-Authors: Obinna Onuaguluchi, Nemkumar Banthia, Keith Gourlay, Gurminder MinhasAbstract:Abstract Repair of deteriorating concrete infrastructure remains a major challenge. The concern is that current Repair materials are not able to prevent premature failure after a Repair has been performed. Thus, an engineered Repair Mortar that can enhance the durability of Repaired composites by mitigating moisture transport and its debilitating influence on deterioration mechanisms such as steel rebar corrosion would be highly coveted. In this study, the influence of reinforcing a Repair Mortar with 0.1% by volume of Nano-Fibrillated Cellulose (NFC) on the capillary water transport in monolithic and composite specimens was investigated. Micro Computed Tomography (CT) imaging was also utilized in evaluating the microstructure of sorptivity test specimens. Thereafter, the influence of Repair Mortars on the corrosion behavior of deformed steel rebar was investigated via natural and accelerated tests. In these tests, concrete substrates had an embedded rebar in it, and Repair Mortars were applied on the top creating a composite specimen with a Repair interface. Some of the parameters measured were surface resistivity, half-cell potential, overlay delamination time, residual rebar pullout load and rebar corrosion degree. Sorptivity tests indicated that the NFC is indeed capable of refining the pore structure through internal curing and thus reducing the capillary uptake of water. Moreover, the tendency of the NFC to entrap micro voids, especially near the Repair interface, thereby indirectly reducing moisture transport and saturation of composite specimens was confirmed by CT imaging. Natural and accelerated corrosion test results demonstrated that NFC addition inhibited rebar corrosion as indicated by reduced rebar corrosion degree and delayed delamination of the Repair overlay. The NFC also provided superior surface resistivity and a higher rebar pullout load capacity after corrosion.
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bond strength between concrete substrate and metakaolin geopolymer Repair Mortar effect of curing regime and pva fiber reinforcement
Cement & Concrete Composites, 2017Co-Authors: Cristina Zanotti, Paulo H R Borges, Aamer Bhutta, Nemkumar BanthiaAbstract:Abstract The suitability of Repairing Portland cement concrete with geopolymer Mortars is explored as a viable way to replace Portland cement in concrete Repairs and reduce their carbon footprint. Bond tests are performed through non-standard slant shear tests with variable bond plane inclination to assess concrete-geopolymer shear bond strength under different combinations of normal and shear stresses at the concrete-geopolymer interface. Interfacial cohesion and friction coefficients, two inherent mechanical properties of the substrate-Repair interface, are extrapolated from experimental data and compared among different types of geopolymer Repairs. The adoption of different curing temperatures for the geopolymer Repair Mortar (20°C and 45°C) and its reinforcement with various contents of Polyvinyl Alcohol fibers (volume fractions Vf = 0%, 0.5%, and 1%) are investigated to optimize the substrate-Repair bond. Mechanical tests are supported by statistical analysis and microscope observation.
Nele De Belie - One of the best experts on this subject based on the ideXlab platform.
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bond strength between concrete and Repair Mortar and its relation with concrete removal techniques and substrate composition
Construction and Building Materials, 2020Co-Authors: Mohammad Ali Yazdi, Elien Dejager, Mats Debraekeleer, Elke Gruyaert, Kim Van Tittelboom, Nele De BelieAbstract:Abstract This study investigates how concrete removal techniques affect substrates of different compositions, and as a result, the bonding with Repair Mortar. To this end, substrate surfaces of different concrete compositions, micro-concrete (MC), gravel concrete (GC) and crushed stone concrete (CC), were treated by using three commonly used removal techniques; hydrodemolition/water-jetting (WJ), jack-hammering (JH) and grit blasting (GB). Automated laser measurements (ALM) and the volumetric sand patch technique were employed to determine the surface roughness of the substrates. The effect of the substrates parameters such as aggregate size and uniformity on the bonding and failure modes was investigated. Uniformity of the substrates was evaluated by porosity measurements. According to the results, bond strength, surface tensile strength, failure modes and surface roughness were dependent on the aggregate size, aggregate shape and uniformity of mixture. The largest aggregate size and highest porosity along with the highest microcrack density and roughness belonged to CC mixtures. A high correlation was observed between the measured water transport and bond strength of samples. Micro-cracking and a weak interfacial transition zone (ITZ) seem to be the detrimental factors influencing the bond strength of samples treated with JH and WJ, respectively. The influence of WJ on the bond strength was dependent on the mix composition parameters such as aggregate size.
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Treatment with nano-silica and bacteria to restore the reduced bond strength between concrete and Repair Mortar caused by aggressive removal techniques
Cement and Concrete Composites, 2026Co-Authors: Mohammad Ali Yazdi, Elke Gruyaert, Kim Van Tittelboom, Nico Boon, Nele De BelieAbstract:Abstract Removal of degraded concrete during Repair activities might have a detrimental impact on the bond strength between the concrete and the Repair Mortar. This research aims to improve the bonding strength in case aggressive removal techniques were used, by the singular and combined application of bacterially induced CaCO3 and colloidal nano-silica (CNS) treatments. Water jetting (WJ) and jackhammering (JH) were compared and the treatments were performed on the substrates prepared with the technique causing the lowest bonding. Pull-off test results on crushed stone concrete (CC) substrates showed that JH substrates possessed the lowest bond strength compared to WJ and unprepared substrates. To assure that reported results are reproducible, pull-off tests were also performed on another type of concrete, gravel concrete (GC). The results showed that in both cases JH-substrates achieved a lower bond strength than unprepared- and WJ-substrates. The reduced bond strength by JH was restored by the CNS treatment irrespective of the concrete composition. Regarding the biodeposition treatment, the spraying technique showed to be superior to the pouring technique. Microstructural analysis confirmed the survival of the bacteria and carbonate precipitation. Porosity of the prepared substrate surfaces was studied by capillary absorption, water absorption (including the gravity effect) and vacuum absorption tests. The reduction in the initial water uptake of CNS-treated samples was evidenced by the precipitation of the silica gel at the superficial layer of the substrate. The efficacy of Energy Dispersive X-Ray Analysis (EDX) to recognize the interlayer of layered composites with a monolithic structure was observed.
Anna Arizzi - One of the best experts on this subject based on the ideXlab platform.
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Mineralogical, Textural and Physical Characterisation to Determine Deterioration Susceptibility of Irulegi Castle Lime Mortars (Navarre, Spain)
MDPI AG, 2019Co-Authors: Graciela Ponce-antón, Anna Arizzi, Maria Cruz Zuluaga, Giuseppe Cultrone, Luis Angel Ortega, Juantxo Agirre MauleonAbstract:Archaeological lime Mortars from the Tower Keep and West perimeter wall of Irulegi Castle (Navarre, Spain) were analysed to determine susceptibility to deterioration. Chemical, mineralogical, textural and physical characterisation was performed by different tests and multianalysis techniques in order to determine the intrinsic features of the original historical Mortars at the castle. Samples from the Tower Keep are more prone to deteriorate compared with the West perimeter wall due to high water absorption capacity and high porosity. A high degree of pore interconnection, high desorption index and the presence of high pore volume in the 0.01 to 1 µm size range affect the Mortar durability since pores retain water longer inside the Mortar. Local environment conditions with persistent annual rainfall, high humidity and temperature variations contribute to the decay process of the original Mortar. Characterisation of historical Mortars not only allows better understanding of susceptibility to deterioration but also helps the design of compatible and durable Repair Mortar for future interventions on historical heritage. Compatibility of new materials with the historical Mortar will be ensured by studying Mortar characteristics and properties
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Repair rendering Mortars for the restoration of the vargas palace in granada spain a comparative study of the Mortar behaviour in the laboratory and on site
Geological Society London Special Publications, 2016Co-Authors: Anna Arizzi, Eduardo Molina, Giuseppe CultroneAbstract:This study gives an example of the steps that a Repair work must include to be successful. It deals with a specific building, Repair material (lime Mortar) and application (render), but also with the study of the Repair Mortar in the laboratory and on site. Firstly, the original materials of the wall were characterized to ensure compatibility with the new Repair Mortars. Secondly, the suitability of different Mortar mixes, made with lime and calcareous aggregate, was assessed by characterizing their properties after 15 months. At the same time, the Repair Mortars were applied in testing panels, and their behaviour under environmental conditions was studied and compared with that of the laboratory Mortars. Mortar properties (shrinkage, adhesion, mineralogy, microstructure and texture) developed differently according to the curing conditions. The carbonation degree was higher in Mortars cured on site (especially those with higher aggregate content), although in both cases it depended on Mortar porosity. Testing the type of application on site was helpful to define the best performance of the designed mixes and to choose the most suitable one among them, which was found to be the 1:6 binder-to-sand ratio Mortar applied in both layers of the render.