Fire Resistance of Structural Concrete Retrofitted with Carbon Fiber–Reinforced Polymer Composites

Reddy, D. V.; Sobhan, Khaled; Young, Jody D.

doi:10.3141/2522-15

Cited by 5 publications

(10 citation statements)

References 5 publications

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“…When CFRP composite suffers from an actual fire [21,22], the carbon fibers on the surfaces of the CFRP close to the fire are considered to be exposed to an oxygen-rich environment. The heat generated from a fire will transfer to the CFRP surface far away from the fire via radiation or convection [23].…”

Section: Introductionmentioning

confidence: 99%

Experimental and Modeling Study of the Evolution of Mechanical Properties of PAN-Based Carbon Fibers at Elevated Temperatures

Xian

2019

Materials

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In the present article, the degradation of the tensile properties of polyacrylonitrile (PAN)-based carbon fibers at elevated temperatures in air was studied experimentally and modeled. The tensile properties, mass loss, surface morphology, and elements and functional groups of carbon fibers were characterized. It can be concluded that the tensile strength and modulus of the carbon fibers decreased remarkably when the exposure temperature exceeded 500 °C. Oxidation at elevated temperatures etched the carbon layer from the skin to the core of the carbon fibers, leading to mass loss. According to the rule of mixtures, an exponential decay model was put forward to describe the degradation behavior of tensile modulus exposed to different temperatures and times. The thickness of the outer layer (Touter) of carbon fibers was obtained to be 0.818 μm. The ultimate exposure temperature was predicted to be 699.4 °C for 30 min, and the ultimate exposure time was 13.2 h at 500 °C. Furthermore, the time–temperature equivalence equation of tensile modulus was deduced. Through the introduction of the normalized oxidation degree, a degradation model of the tensile modulus at any exposure temperature (~800 °C) and time (~800 min) was also proposed. From the elastic mechanics theory for anisotropic solids, the degradation model of tensile strength exposed to elevated temperature was confirmed. It can be observed that the proposed model had good agreement with the experimental results.

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Section: Introductionmentioning

confidence: 99%

Experimental and Modeling Study of the Evolution of Mechanical Properties of PAN-Based Carbon Fibers at Elevated Temperatures

Xian

2019

Materials

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“…The current investigation is a follow-up to earlier studies addressing the size-effect on fire exposure of uncorroded reinforced concrete beams (Reddy et al , 2015a, 2015b). In those studies, series of fire tests were performed on 152.4 mm × 152.4 mm × 533.4 mm (6 in.…”

Section: Introductionmentioning

confidence: 94%

“…It was determined that the 30-min exposure time retained the integrity better than the 2-h and 1-h exposure times. This was based on dimensional analysis, conducted to develop a relationship between full-scale and small-scale specimens that would allow fire testing to be conducted on small-scale specimens with truncated time durations (Reddy et al , 2015a). Using this relationship, small-scale specimens could be exposed to fire conditions in accordance with ASTM E-119-12a (2012) at a reduced exposure time, 30 min, demonstrating comparable full-scale behavior.…”

Section: Introductionmentioning

confidence: 99%

Fire resistance of corroded high-strength structural concrete

Sobhan

Reddy

Martínez

2020

JSFE

Self Cite

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Purpose The exposure of reinforced concrete structures such as high-rise residential buildings, bridges and piers to saline environments, including exposure to de-icing salts, increases their susceptibility to corrosion of the reinforcing steel. The exposure to fire can further deteriorate the structural integrity of corroded concrete structures. This combined effect of corrosion damage and fire exposure is not generally addressed in the structural concrete design codes. The synergistic combination of the effects of corrosion and fire forms the basis of this paper. Design/methodology/approach Concrete beam specimens with different strengths were prepared, moist-cured and corroded with impressed current. Later, they were “crack-scored” for corrosion evaluation, after which half were exposed to fire in a gas kiln. The fire damage was evaluated by nondestructive testing using ultrasonic pulse velocity. Next, all specimens were tested for residual flexural strength. They were then autopsied, and the level of corrosion was determined based on mass loss of the reinforcement. Findings For corroded specimens, the flexural capacity loss because of fire exposure increases as the compressive strength increases. In general, the higher the crack score, the higher the corresponding mass loss, unless some partial/segmental debonding of the reinforcement occurred. The degree of corrosion increases with decreasing compressive strength. The residual moment capacity, based on analytically determined capacities of uncorroded and nonfire-exposed beams, was significantly lower than those of uncorroded beams exposed to fire. Originality/value The combined effects of corrosion and fire on the mechanical properties of structural concrete are relatively unknown, and no guidance is available in the existing design codes to address this issue. Accordingly, the findings of the paper are expected to be valuable to both researchers and design engineers and can be regarded as the initial investigation on this topic.

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“…A reduction in the fire resistance rating was observed in the reduced cross-section via the good protection layer during elevated temperature exposure tests [11], [12]. Utilization of carbon nanotubes (CNTs) is highlighted amongst the research areas in the field of nanotechnology.…”

Section: Introductionmentioning

confidence: 99%

Use of Carbon Nanotubes in the Retrofitting of Reinforced Concrete Beams With an Opening and the Effect of Direct Fire on Their Behaviour

Hassan¹

2018

GEOMATE

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Carbon nanotubes (CNTs) are used to enhance the performance of nano-composites because of their high strength and remarkable physical properties. An experimental study was designed to investigate the use of CNTs in a ferrocement mix as an advanced technique for externally retrofitting for shear zone opening of reinforced concrete beams. The main parameters in this work are opening size, ferrocement techniques (CNTs and wire mesh), and fire exposure. The ferrocement technique is used to retrofit the reduction of open beams strength, whether exposure to fire occurred or not. The burned beams are loaded at 30 kN at room temperature and then subjected to a direct fire, followed by cooling with water before the load was finally increased to failure. In addition, the strength reduction of the test specimens was increased during firing with an increase in the opening size; strengthening with ferrocement decreased this reduction, deflection, and change in crack pattern shape and improved beam ductility. Carbon nanotubes improve the efficiency of retrofitting by ferrocement compared to the use of steel wire mesh in the ferrocement mix.

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Fire Resistance of Structural Concrete Retrofitted with Carbon Fiber–Reinforced Polymer Composites

Cited by 5 publications

References 5 publications

Experimental and Modeling Study of the Evolution of Mechanical Properties of PAN-Based Carbon Fibers at Elevated Temperatures

Experimental and Modeling Study of the Evolution of Mechanical Properties of PAN-Based Carbon Fibers at Elevated Temperatures

Fire resistance of corroded high-strength structural concrete

Use of Carbon Nanotubes in the Retrofitting of Reinforced Concrete Beams With an Opening and the Effect of Direct Fire on Their Behaviour

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