Evaluation of bond strength between steel rebars and concrete for heat-damaged and repaired beam-end specimens

Ghazaly, Nesma; Rashad, Ahmed; Kohail, Mohamed; Nawawy, Omar El

doi:10.1016/j.engstruct.2018.08.056

Cited by 45 publications

(6 citation statements)

References 29 publications

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“…Also, the effect of using superplasticizers with different chemical bases is thoroughly investigated and naphthalin based admixtures seemed to have remarkable merits with Nano additives (Serag, Mohamed et al, 2014;Raouf et al, 2014). Enhancement in concrete mechanical behavior, as compressive strength, bond, durability, permeability, beside corrosion and elevated temperature resistance by using small ratios of Nano Silica (1.5 per cent to 3 per cent) in concrete mixes was not only reported by one of the authors (Ahmed et al, 2018;Serag et al, 2017;El-Feky et al, 2016), but similar results are reported by , Mohamed et al (2016); , ; Sherif (2019), Irshidat and Al-Saleh (2017); Mohammed et al (2014), Morsy et al (2010); Birgisson et al (2012); Ergün et al (2016); Ghazy et al (2015), Shamseldein et al (2018); Ghazaly et al (2018).…”

Section: Introductionsupporting

confidence: 74%

Assessment of mechanical and fire resistance for hybrid nano-clay and steel fibres concrete at different curing ages

Shalby

Elkady

Nasr

et al. 2019

JSFE

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Purpose Nano-Clay (NC) is reported as a candidate partial replacement for cement, due to its abundance and relatively low cost - beside reported promotion of different concrete properties. On the other hand, Steel Fibres (SF) has proven to have a positive effect on post fire exposure residual strength of concrete. This paper aims to present the outcomes of a comprehensive research program assessing a hybrid mix between NC and SF in concrete mixtures (NCSF-CRETE). Design/methodology/approach Physical chemical and physical characterization of NC is performed using different tools as XRF spectrometer, and TEM micrograph. Fresh concrete properties of NSCF-CRETE as slump and air content are investigated. Enhancement in permeability using NSCF is verified by comparing its resistance to the penetration of chlorides resistance with regular concrete mix. Besides, the proposed NCSF-CRETE compressive strength is evaluated compared to mixes with NC and SF each used separately at different curing ages. Besides, NSCF and compared mixes are exposed to an indirect fire testing program – two hours exposure – for: 300, 450 and 600°C. Degradation in compressive strength was investigated after exposure to different temperatures and percentage of residual strength is reported. Findings Results indicated an improved performance of NCSF -CRETE of about 40% compared to regular concrete in compressive strength at normal conditions. This improvement extended to its behavior when subjected to indirect fire exposure NSCF also maintained 40% more strength than the residual in regular concrete mix – which suffered severe damage – after 2 h exposure to 600°C. Originality/value Using NCSF-Crete allows retrofitting the structure after exposure to such drastic conditions.

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Section: Introductionsupporting

confidence: 74%

Assessment of mechanical and fire resistance for hybrid nano-clay and steel fibres concrete at different curing ages

Shalby

Elkady

Nasr

et al. 2019

JSFE

Self Cite

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“…of its value at room temperature. For temperatures above 400 ºC, a distinct fall in maximum residual bond strength is observed [63,73,99,101,109,110,83,86,88,89,92,[94][95][96]. Source: Author (2021).…”

Section: Effect Of Elevated Temperature Exposure On Bond Strength And...mentioning

confidence: 99%

“…Similar conflicting results have been reported for the bar slip at maximum bond strength. In some experiments, a higher slip was observed [63,73,83,86,99], whereas others exhibited a reduction of the slip at bond failure [89,101,110].…”

Section: Effect Of Elevated Temperature Exposure On Bond Strength And...mentioning

confidence: 99%

“…show that increasing the embedment length from 40 to 100 mm reduced the bond strength by up to 41% at room temperature, 46% at 400 ºC, and 55% at 800 ºC. Ghazaly et al [101] evaluated the bond strength for heat-damaged and repaired beam-end specimens. The authors observed a slight decrease in bond strength with the increase of the bonded length from 5d to 8d.…”

Section: Bar Diameter and Embedment Lengthmentioning

confidence: 99%

“…This could be explained by the fact that a thicker concrete cover is able to act better as a thermal barrier and causes fewer thermal cracks [82]. Generally, the thicker the concrete cover, the higher the bond strength and the ultimate slip at failure [81,82,86,87,92,101,104].…”

Section: Concrete Cover and Bar Diametermentioning

confidence: 99%

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Experimental evaluation of the residual concrete-reinforcement bond after exposure to elevated temperatures

Andrade¹

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The composite behavior of reinforced concrete structures is directly related to the bond between concrete and reinforcement. When a reinforced concrete structure is subjected to a fire event, the bond is damaged and the force-transfer mechanism is compromised, as well as the resistant capacity of the structure itself. This study consists of a review of post-fire concrete- reinforcement bond relationship and an experimental assessment of the influence of exposure to elevated temperatures on the bond between these materials. First, it was reviewed the state- of-the-art research on post-fire bond properties, as well as the parameters influencing bond relationship development after exposure to elevated temperatures. This work also presents an experimental assessment of the influence of degradation of concrete and reinforcing steel, induced by elevated temperatures, on the bond relationship between the materials and the influence of concrete cover to bar diameter ratio on concrete-reinforcement bond failure mechanism. The findings showed that bond degradation is directly related to the damage to the concrete and that the reinforcing steel is negligibly affected by temperatures under 600 ºC. It was also observed that exposure at 200 ºC had a positive effect both on the residual mechanical properties of concrete and residual bond strength. Exposure to higher temperatures progressively reduced the mechanical properties of concrete and the bond strength measured after the fire situation. Moreover, the bond failure mechanism was observed to shift from pull- out to splitting due to the concrete damage at elevated temperatures, although it could not be easily distinguished. It was also concluded that, even though the data available on the literature are extremely scattered, the bond strength prescribed by international standards for structures design is safe both at room temperature and after exposure to elevated temperatures. Keywords: Reinforced concrete. Bond strength. Elevated temperatures. Bond-slip relationship. Bond failure mechanism.

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Geopolymer concrete containing nanomaterials—a step toward sustainable construction

Indwar,

Mishra,

Titiksh

2024

Environ Sci Pollut Res

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Evaluation of bond strength between steel rebars and concrete for heat-damaged and repaired beam-end specimens

Cited by 45 publications

References 29 publications

Assessment of mechanical and fire resistance for hybrid nano-clay and steel fibres concrete at different curing ages

Assessment of mechanical and fire resistance for hybrid nano-clay and steel fibres concrete at different curing ages

Experimental evaluation of the residual concrete-reinforcement bond after exposure to elevated temperatures

Geopolymer concrete containing nanomaterials—a step toward sustainable construction

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