Mechanical Properties of Microsteel Fiber Reinforced Concrete and Its Gradient Design in the Partially Reinforced RC Beam

He, Xiujuan; Fang, Yakun; Luo, Qi; Cao, Yong; Lu, Han; Ma, Ruijuan

doi:10.1155/2020/6639312

Cited by 10 publications

(5 citation statements)

References 22 publications

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“…Increasing the steel fibre content at ambient temperature increased the concrete modulus of elasticity. This agrees with previous findings [44,46,[61][62][63][64][65][66][67][68][69][70]. The relatively high modulus of elasticity for steel fibre and good bond with the surrounding matrix limited the strain development during loadings.…”

Section: Modulus Of Elasticity and Modulus Of Resiliencesupporting

confidence: 92%

Impact Behaviour of Steel-Fibre-Reinforced Alkali-Activated Slag Concrete Exposed to Elevated Temperatures

Soliman

2023

Materials

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Concrete protective structures are mainly meant to withstand impact loads. However, fire events weaken concrete and reduce its impact resistance. This study investigated the impact behaviour of steel-fibre-reinforced alkali-activated slag (AAS) concrete before and after exposure to elevated temperatures (i.e., 200 °C, 400 °C, and 600 °C). Hydration products’ stability under elevated temperatures, their effects on the fibre–matrix bond, and, consequently, AAS’s static and dynamic responses were investigated. The results reveal that adopting the performance-based design concept to achieve a balance between AAS mixtures’ performance under ambient and elevated temperatures is a crucial designing aspect. Advancing hydration products’ formation will increase the fibre–matrix bond at ambient temperature while negatively affecting it at elevated temperatures. High amounts of formed and, eventually, decomposed hydration products at elevated temperatures reduced the residual strength due to lowering the fibre–matrix bond and developing internal micro-cracks. Steel fibre’s role in reinforcing the hydrostatic core formed during impact loads and delaying crack initiation was emphasized. These findings highlight the need to integrate material and structure design to achieve optimum performance and that low-grade materials can be desired based on the targeted performance. A set of empirical equations for the correlation between steel fibre content in the AAS mixture and corresponding impact performance before and after fire exposure was provided and verified.

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Section: Modulus Of Elasticity and Modulus Of Resiliencesupporting

confidence: 92%

Impact Behaviour of Steel-Fibre-Reinforced Alkali-Activated Slag Concrete Exposed to Elevated Temperatures

Soliman

2023

Materials

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“…The vertical coordinate is the shear strength v = V/(bh0), and the horizontal coordinate is the beam group number. It can be seen that the interface treatment between the ECC and concrete has no significant effect on the cracking load and ultimate load of the beams [34]. The results of the present study show that, in comparison with RC beams subjected to the same conditions, the average increase in shear capacity for beams with a combination of web reinforcement within the designed shear-to-span ratio is 6%.…”

Section: Effect Of Interlayer Interface Treatment On Shear-bearing Ca...mentioning

confidence: 51%

“…The vertical coordinate is the shear strength v = V/(bh0), and the horizontal coordinate is the beam group number. It can be seen that the interface treatment between the ECC and concrete has no significant effect on the cracking load and ultimate load of the beams [34]. The available FE analysis software ABAQUS was used to build the FE analysis model of the combined ECC-concrete beam.…”

Section: Effect Of Interlayer Interface Treatment On Shear-bearing Ca...mentioning

confidence: 99%

Experimental Study of the Shear Performance of Combined Concrete–ECC Beams without Web Reinforcement

Cheng,

Du,

Wang

et al. 2023

Materials

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Background: Shear damage of beams is typically brittle damage that is significantly more detrimental than flexural damage. Purpose: Based on the super-high toughness and good crack control ability of engineered cementitious composites (ECC), the shear performance of concrete–ECC beams was investigated by replacing a portion of the concrete in the tensile zone of reinforced concrete beams with ECC and employing high-strength reinforcing bars to design concrete–ECC beams. The purpose of this investigation is to elucidate and clarify the shear performance of concrete–ECC beams. Methodology/approach: Experimental and FE analyses were conducted on the shear performance of 36 webless reinforced concrete–ECC composite beams with varied concrete strengths, shear-to-span ratios, ECC thicknesses, and interfacial treatments between the layers. Results: The results indicate that the effect of the shear-to-span ratio is greater, the effect of the form of interface treatment is smaller, the effect is weakened after the ECC thickness is greater than 70 mm (i.e., the ratio of the replacement height to section height is approximately 0.35), the shear resistance is reduced when the hoop rate is greater, and the best shear resistance is obtained when the ECC 70 mm thickness and the hoop rate of 0.29% are used together. Conclusions: This study can serve as a technical reference for enhancing the problems of low durability and inadequate fracture control performance of RC beams in shear and as a guide for structural design research.

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“…Compared with the carbon fiber sheet, the interface between epoxy/concrete is more vulnerable to damage under hygrothermal conditions . Although reinforcement of concrete structures is a systemic issue, − understanding the mechanism of the epoxy/concrete interfacial degradation is essential for ensuring a good bearing capacity as well as long-term durability of CFRP composites in a hygrothermal environment.…”

Section: Introductionmentioning

confidence: 99%

Interfacial Degradation of Calcium Silicate Hydrate and Epoxy under a Hygrothermal Environment: An Experimental and Molecular Model Study

Luo

Zhang

et al. 2023

J. Phys. Chem. C

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The adhesion at the concrete/epoxy interface is crucial to the reinforcement of carbon fiber-reinforced polymer (CFRP) sheets. The multiscale mechanism of adhesion, particularly under a hygrothermal environment, yet remains largely unclear. This paper combines molecular dynamics (MD) and synthesis experiments of a novel single-phase calcium silicate hydrate (C-S-H) and epoxy composite to investigate the combined effects of aggressive chemicals and temperature on the bonding properties. MD models were constructed under various conditions on C-S-H/epoxy composites, whose equilibrium configuration, dynamic property, bond connection, interfacial interaction energy, and mechanical properties were quantified. In addition, the experiments were carried out under different temperatures and humidity conditions to explore the macroscopic splitting tensile property of the composites and further validate the MD results. The MD results suggest that the Ca ions on the C-S-H surface are crucial to the adhesion by forming Ca−O and Ca−N bonds with epoxy. However, these bonds were reduced in the presence of water molecules, with a reduction also of the interfacial energy. The degradation effects are exacerbated by the presence of NaCl solution, as Na ions gather around the interfacial region of C-S-H/ epoxy, further accumulating water molecules by forming hydrated ion clusters. This process is accelerated by elevated temperature. The experiment results suggest that without the influence of NaCl solution, a moist C-S-H surface turns to gain a stronger bonding with epoxy when the curing temperature is higher (40, 60 °C). Meanwhile, the bonding properties of a dry C-S-H surface and epoxy are less sensitive to temperature. This work provides new insight into understanding the bonding mechanism on the C-S-H/epoxy interface and may benefit the engineering application of CFRP-concrete reinforcement.

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Mechanical Properties of Microsteel Fiber Reinforced Concrete and Its Gradient Design in the Partially Reinforced RC Beam

Cited by 10 publications

References 22 publications

Impact Behaviour of Steel-Fibre-Reinforced Alkali-Activated Slag Concrete Exposed to Elevated Temperatures

Impact Behaviour of Steel-Fibre-Reinforced Alkali-Activated Slag Concrete Exposed to Elevated Temperatures

Experimental Study of the Shear Performance of Combined Concrete–ECC Beams without Web Reinforcement

Interfacial Degradation of Calcium Silicate Hydrate and Epoxy under a Hygrothermal Environment: An Experimental and Molecular Model Study

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