scholarly journals Comparison of Bond Properties Between ALWSCC and Steel Bars Based on Different Test Methods

2021 ◽  
Author(s):  
Jianhui Yang ◽  
Wenchao Zhi ◽  
Xujun Tang ◽  
Qinting Wang ◽  
Tom Cosgrove
Keyword(s):  
Seismic Analysis ◽  
Test Methods ◽  
Normal Weight ◽  
Bond Properties ◽  
Normal Weight Concrete ◽  
Bond Performance ◽  
Pull Out ◽  
Steel Bars ◽  
Before And After ◽  
Bond Property

Reasonable evaluation of the bond performance between steel bars and concrete has important theoretical and practical value for reinforced concrete structural design and seismic analysis. The stress (τ) – strain (ε) formula is corrected based on a pull-out test, and the load (F) – deflection (w) curves are analyzed according to the change of stiffness before and after crack appearance based on a beam test, and new estimation formulas are given. At the same time, the bond properties are compared between all-lightweight shale ceramsite concrete (ALWSCC) and normal weight concrete (NWC). The results show that the bond property of ALWSCC is better than NWC. The bond stresses of pull-out specimens and beam specimens are the same or similar under equal conditions, but the ultimate load (F0) of the former is about 3.66 times that of the latter, the peak slip (S0) of the latter is 4.80 times that of the former, and the latter has significant splitting or pull-out failure characteristics. The peak slip (S0) in this paper is larger than that in the related literature, where the pull-out specimens are no more than 10 mm, and are generally less than 2 mm, while the beam specimens are not more than 3 mm, with the others generally around 1 mm. The research results have reference values and guiding significance for similar experimental research and engineering practice.

BOND BEHAVIOR OF LIGHTWEIGHT FIBER REINFORCED CONCRETE

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Klaus Holschemacher ◽  
Ahsan Ali ◽  
Shahid Iqbal
Keyword(s):  
Reinforced Concrete ◽  
Lightweight Concrete ◽  
Normal Weight ◽  
Fiber Reinforced Concrete ◽  
Experimental Program ◽  
Fiber Reinforced ◽  
Bond Behavior ◽  
Normal Weight Concrete ◽  
Air Content ◽  
Pull Out

In construction industry lightweight concrete and fiber reinforced concrete are being used for many years. The former is known for brittle nature, light in weight and low thermal conductivity properties. It also offers better workability when compared to the normal weight concrete for the same slump value. These properties are however affected by addition of discrete fibers. Among the affected properties is also the bond between steel and concrete surrounding it. The integrity of a reinforced concrete member is not ensured in the absence of adequate bond. Due to limited literature on the subject matter, an experimental program was carried out to understand the bond behavior in lightweight concrete after fiber inclusion. For the purpose modified pull-out specimens made of Lightweight Fiber Reinforced Concrete (LWFC) were tested. Hooked end steel fibers having length 35 mm and diameter 0.5 mm (l/d = 0.7) were incorporated in dosages of 0, 20, and 40 kg/m3. Besides pull-out specimens, testes were also carried out for fresh and hardened properties of LWFC. Tests results indicate higher pull-out loads for higher fiber contents. The average increase in ultimate bond strength was observed at 28% and 2% for 40 kg/m3 and 20 kg/m3 fiber contents respectively. The fresh concrete density, compressive strength of mixes reduced and air-content values increased with increase in fiber content.

Influence of specimen dimensions and reinforcement corrosion on bond performance of steel bars in concrete

2020 ◽  
Vol 23 (9) ◽  
pp. 1759-1771
Author(s):  
Bai Zhang ◽  
Hong Zhu ◽  
Jun Chen ◽  
Ou Yang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Experimental Results ◽  
Reinforcement Corrosion ◽  
Element Analysis ◽  
Bond Slip ◽  
Bond Performance ◽  
Concrete Deterioration ◽  
Pull Out ◽  
Steel Bars

To study the deterioration of bond performance between concrete and corroded steel bars with designed corrosion levels of 0%, 0.5%, 1.0%, 2.0%, 5.0%, 8.0%, and 10.0%, pull-out tests were performed on cube specimens with the dimensions of 10 D × 10 D × 10 D, where D is the diameter of longitudinal rebars ( D = 14, 20, and 25 mm, respectively). The experimental results indicated that with the specimen dimensions increased, the expansive cracks induced by corrosion products appeared earlier and the maximum expansive cracking width was larger at the same corrosion levels. The bond strength and the initial bond stiffness first increased and then dramatically decreased as the concrete deterioration and reinforcement corrosion levels increased for each specimen dimension, whereas the specimens with the larger diameter ( D = 25 mm) were more sensitive to the corrosion than those with the smaller diameter ( D = 14, 20 mm). The free-end slip and the energy dissipation for each specimen dimensions, which decreased slowly with increasing corrosion levels before the corrosion-induced cracks and then weakened rapidly when the corrosion-induced cracks appeared, was almost independent of the influence on corrosion levels after the corrosion-induced cracks appeared. Based on the experimental results, a simplified expression for the calculation of residual bond stress and an empirical model of the bond–slip constitutive equation that considers the influence of reinforcement corrosion were proposed, which can be used in finite element analysis of corroded reinforced concrete.

Experimental Investigation of Bond between GFRP Reinforcement and Concrete

2020 ◽  
Vol 309 ◽  
pp. 140-145
Author(s):  
Ivan Hollý
Keyword(s):  
Test Methods ◽  
Transport Infrastructure ◽  
Mechanical Interlocking ◽  
Composite Action ◽  
Pull Out ◽  
Steel Bars ◽  
Glass Fiber Reinforcement ◽  
High Alkalinity ◽  
Gfrp Reinforcement ◽  
Gfrp Rebars

The reinforcing steel embedded in concrete is generally protected against corrosion by the high alkalinity (pH = 12.5 to 13.5) of the concrete pore solution. The structural degradation of concrete structures due to reinforcement’s corrosion has an impact on the safety, serviceability and durability of the structure. The corrosion of reinforcements in the construction of a transport infrastructure (especially bridges), parking areas, etc., is primarily initiated by chlorides from de-icing salts. Glass fiber reinforcement polymer (GFRP) bars are suitable alternatives to steel bars in reinforced concrete applications. The bond between concrete and reinforcement is one of the basic requirements for the composite action of both materials. The transfer of forces between the steel reinforcement and the concrete is provided by the following mechanisms: adhesion, friction and mechanical interlocking. The bond between GFRP reinforcement and concrete is different and it is ensured by friction and mechanical interlocking of the rebar surface. The chemical bond does not originate between GFRP reinforcement and the surrounding concrete, so adhesion does not contribute to transfer of the bond forces. Some few test methods are used to determine the bond between GFRP reinforcement and concrete. The pull-out tests were used to determine the bond behavior between GFRP rebars and concrete. This paper describes the preparation, process, results and evaluation of the pull-out tests.

Properties of Concrete Containing Scrap-Tire Chips

2011 ◽  
Vol 399-401 ◽  
pp. 1251-1256 ◽  
Author(s):  
Wai Ching Tang ◽  
Hong Zhi Cui ◽  
Yiu Lo
Keyword(s):  
Environmental Issues ◽  
Normal Weight ◽  
Scrap Tire ◽  
Scrap Tires ◽  
Bonding Agents ◽  
Normal Weight Concrete ◽  
Tire Chips ◽  
Increase With Increase ◽  
The World ◽  
Concrete Matrix

Nowadays, one of the most essential environmental issues around the world is to deal with the scrap tire problem. Tires that are used, rejected or unwanted are classified as scrap tires and need to be managed responsibly. In this paper, the scrap tires were shredded into pieces and used to mix with normal weight concrete. Extensive laboratory tests were carried out and the focus of this paper was to characterize the mechanical and permeability properties of concrete containing scrap tires. The main parameters studied were chipped tire content and size. The results showed that the scrap-tire chips without adding special bonding agents apparently showed an even distribution in the mortar and concrete matrix. The elastic modulus, compressive and tensile strengths of scrap tire concrete in general were found lower than that of the control concrete and the differences became significant when the content and size of chipped tires in the mix were increased. Besides, the coefficients of water permeability of concrete were found to increase with increase of chipped tires in the mix.

Experimental Research on Interfacial Bond Performance in Rock Anchor with High-Performance Grouting Medium

2012 ◽  
Vol 517 ◽  
pp. 932-938 ◽  
Author(s):  
Zhi Fang ◽  
Hong Qiao Zhang
Keyword(s):  
Rock Mass ◽  
Bond Strength ◽  
High Performance ◽  
Interfacial Bond ◽  
Interfacial Bond Strength ◽  
Bond Performance ◽  
Pull Out ◽  
Steel Bar ◽  
Reactive Powder ◽  
Ground Anchor

There exist the problems such as low bond strength and bad durability in the ordinary grouting slurry of the ground anchor system at present. The high-performance grouting mediums RPC (Reactive Powder Concrete) and DSP (Densified Systems containing homogeneously arranged ultrafine Particles) would become the potential replacement of grouting medium in ground anchor resulting from their high compressive strength, durability and toughness. Based on a series of pull-out tests on ground anchors with different high-performance grouting medium of RPC and DSP , different bond length in the construction field, the bond performance on the interfaces between anchor bolt (deformed steel bar) and grouted medium as well as between grouted medium and rock mass was studied. The results indicate that the interfacial bond strength between RPC or DSP and deformed steel bolt ranges within 23-31Mpa, far greater than that (about 2-3MPa) between the ordinary cementitious grout and deformed steel bar. Even though the interfacial bond strength between the grouted medium and rock mass of limestone was not obtained in the test since the failure mode was pull-out of those steel bar rather than the interface shear failure between grouted medium and rock mass, the bond stress on the interface reached 6.2-8.38 MPa, also far greater than the bond strength (about 0.1-3MPa) between the ordinary cementitious slurry and rocks.

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