scholarly journals An experimental study of damage characteristics at bond of RC after microwave heating

2021 ◽  
Vol 73 (02) ◽  
pp. 107-117
Keyword(s):  
Thermal Damage ◽  
Interfacial Bond ◽  
Bond Slip ◽  
Damage Characteristics ◽  
Steel Rebar ◽  
Pull Out ◽  
Irradiation Power ◽  
Splitting Failure ◽  
Microwave Irradiations ◽  
Characteristic Points

With an increase in urban construction waste, and in order to find an effective method of microwave-assisted mechanical RC regeneration, thermal damage characteristics of the interfacial bond between steel rebar and concrete after different microwave irradiations are analysed in this paper. The results show that, with an increase in microwave power, the overall failure mode of the specimen changes from splitting failure to pull-out failure. Bond slip curves and the corresponding fitting equations were obtained at various levels of microwave irradiation. By analysing characteristic points of the curve, 3500W was determined as a reasonable irradiation power.

scholarly journals Finite element modelling of monotonic pull-out test of deformed steel rebar embedded in well-confined concrete

2021 ◽  
Vol 331 ◽  
pp. 05012
Author(s):  
Patria Kusumaningrum ◽  
Gigih Muslim Prayogo ◽  
Sri Tudjono
Keyword(s):  
Finite Element ◽  
Finite Element Modelling ◽  
Empirical Equation ◽  
Bond Stress ◽  
Confined Concrete ◽  
Bond Slip ◽  
Steel Rebar ◽  
Bond Model ◽  
Pull Out ◽  
Good Agreement

A finite element study carried out using LS DYNA and aimed to simulate the monotonic pull-out test of deformed steel rebar embedded in concrete is presented in this paper. Three models of the interface between deformed steel rebar and well-confined concrete, i.e. perfect bond model and two bond-slip models are observed and compared. Bond stress-slip response and rebar stress-slip response obtained numerically are validated with experimental data and empirical equations available from the literature. The full bond model overestimates the response, providing higher rebar stress. In the bond-slip models, good agreement is observed between numerical and experimental bond stress and rebar Stress–slip responses. The empirical equation of bond-slip proposed by Murcia-Delso and Shing (2014) is found to overestimate the peak bond stress.

Bond-Slip Mechanisms in Steel Micro-Fiber Reinforced Cement Composites

1994 ◽  
Vol 370 ◽  
Author(s):  
N. Banthia ◽  
N. Yan ◽  
C. Chan ◽  
C. Yan ◽  
A. Bentur
Keyword(s):  
Bond Strength ◽  
Silica Fume ◽  
Cement Composites ◽  
Interfacial Bond ◽  
Interfacial Bond Strength ◽  
Bond Slip ◽  
Pull Out ◽  
Fiber Size ◽  
The Matrix ◽  
Reinforced Cement

AbstractBond-slip characteristics for steel micro-fibers bonded in cement-based matrices were investigated by conducting single fiber pull-out tests. The influence of the following factors was investigated: fiber inclination, fiber size, fiber embedded length and matrix refinement using silica fume. It was found that the bond-slip characteristics of fibers aligned with respect to the loading direction were necessarily superior than those inclined at an angle. Inclined fibers supported smaller peak pull-out loads and absorbed lesser pull-out energies than the aligned fibers. The use of silica fume in the matrix was found to improve both the average interfacial bond strength and the maximum interfacial bond strength between the fiber and the matrix.

Test Research on Bonding Strength between GFRP Anchor Bolt and Concrete under Corrosive Conditions

2012 ◽  
Vol 212-213 ◽  
pp. 904-911
Author(s):  
Xie Xing Tang ◽  
Xiao Yong Luo ◽  
Kai Lei Li ◽  
Ya Chuan Kuang
Keyword(s):  
Bonding Strength ◽  
Failure Modes ◽  
Bond Slip ◽  
Anchor Bolt ◽  
Pull Out ◽  
Geological Conditions ◽  
Splitting Failure ◽  
Slip Displacement ◽  
Anchor Bolts ◽  
Expansion Force

In practical projects, GFRP anchor bolts are in complex geological conditions with corrosive factors such as acid, alkalis, salt and freeze-thaw circle. In corrosive conditions, the bonding strength of GFRP anchor bolts are in direct relation to safety of anchoring works. Based on comparative tests on bonding strength between GFRP anchor bolt and concrete, failure modes in pull-out tests of GFRP anchor bolt and concrete are mainly pull-out failure and splitting failure. Pull-out failure is a chemical and mechanical interlocking failure between GFRP anchor bolts and concrete cubes, which can actually reflect the bonding status of bolts and concrete cubes. Splitting failure is a failure that the radial expansion force caused when the GFRP anchor bolt are bearing forces damages the concrete if it is of low strength or insufficient in thickness of protection layer and thus leads to boding failure. From the analysis on test results of bond-slip performance, the bonding strength decline the most in alkalis conditions: the bonding strength decreases by 23% after 1500 hours of corrosion and the slip displacement increases by 2.4mm; in acid and salt conditions, after 1500 hours of corrosion the bonding strength decreases by 19% and 17% and slip displacement increase by 1.6mm and 1.8mm, respectively. Based on analysis of nonlinear curve fitting on test data of bonding strength in three corrosive conditions, three empirical equations of degradation of bonding strength are fitted for GFRP anchor bolts in three corrosive conditions. Compared with data from reference [13], the bonding strength of GFRP anchor bolts working in acid, alkalis and salt geological conditions for 50 years decrease by 19.5%, 25% and 19.2%, respectively. These research results supply a test basis for GFRP anchor bolts used in complex geological conditions.

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.

Bond behaviour of chemically prestressed textile reinforced concrete

2019 ◽  
Author(s):  
Katarzyna Zdanowicz ◽  
Boso Schmidt ◽  
Hubert Naraniecki ◽  
Steffen Marx
Keyword(s):  
Reinforced Concrete ◽  
Bond Strength ◽  
Crack Width ◽  
Research Programme ◽  
Textile Reinforced Concrete ◽  
Self Compacting Concrete ◽  
Bond Behaviour ◽  
Bond Slip ◽  
Laser Sensors ◽  
Pull Out

<p>The bond behaviour of concrete specimens with carbon textile reinforcement was investigated in the presented research programme. Pull-out specimens were cast from self-compacting concrete with expansive admixtures and in this way chemical prestress was introduced. The aim of the research was to compare bond behaviour between prestressed specimens and non-prestressed control specimens. During pull-out tests, the pull-out force and notch opening were measured with a load cell and laser sensors. Further, bond - slip and pull-out force - crack width relationships were drawn and compared for prestressed and non-prestressed specimens. Chemically prestressed specimens reached 24% higher bond strength than non-prestressed ones. It can be therefore concluded, that chemical prestressing positively influences the bond behaviour of concrete with textile reinforcement and thus better utilisation of its properties can be provided.</p>

Bond‐Slip Behavior Between GFRP Bars and Mortar Based on Pull‐Out Tests

2018 ◽  
Vol 40 (7) ◽  
pp. 2840-2849
Author(s):  
Qingping Jin ◽  
Guangbo Wang ◽  
Tingying Liang ◽  
Peixia Chen
Keyword(s):  
Bond Slip ◽  
Gfrp Bars ◽  
Pull Out

Bond behavior of high strength concrete under reversed pull-out cyclic loading

2002 ◽  
Vol 29 (2) ◽  
pp. 191-200 ◽  
Author(s):  
M Alavi-Fard ◽  
H Marzouk
Keyword(s):  
Cyclic Loading ◽  
Bond Strength ◽  
High Strength Concrete ◽  
Concrete Strength ◽  
High Strength ◽  
Displacement Curve ◽  
Bond Slip ◽  
Strength Concrete ◽  
Pull Out ◽  
Normal Strength

Structures located in seismic zones require significant ductility. It is necessary to examine the bond slip characteristics of high strength concrete under cyclic loading. The cyclic bond of high strength concrete is investigated under different parameters, including load history, confining reinforcement, bar diameter, concrete strength, and the rate of pull out. The bond strength, cracking, and deformation are highly dependent on the bond slip behavior between the rebar and the concrete under cyclic loading. The results of cyclic testing indicate that an increase in cyclic displacement will lead to more severe bond damage. The slope of the bond stress – displacement curve can describe the influence of the rate of loading on the bond strength in a cyclic test. Specimens with steel confinement sustained a greater number of cycles than the specimens without steel confinement. It has been found that the maximum bond strength increases with an increase in concrete strength. Cyclic loading does not affect the bond strength of high strength concrete as long as the cyclic slip is less than the maximum slip for monotonic loading. The behavior of high strength concrete under a cyclic load is slightly different from that of normal strength concrete.Key words: bond, high strength, cyclic loading, bar spacing, loading rate, failure mechanism.

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