scholarly journals Experimental Study of Post Installed Rebar Anchor Systems for Concrete Structure

2020 ◽  
Vol 16 (2) ◽  
pp. 308-319
Author(s):  
Haidar H. Haidar ◽  
Faten I. Mussa ◽  
Abbas O. Dawood ◽  
Ahmed A. Ghazi ◽  
Rassel A. Gabbar
Keyword(s):  
Experimental Study ◽  
Bond Strength ◽  
Hole Diameter ◽  
The Other ◽  
Bonding Agents ◽  
Pull Out ◽  
Varied Chemical ◽  
Anchor Systems ◽  
Cylindrical Samples ◽  
Concrete Interface

AbstractThis study investigated the effectiveness of several types of adhesives used in post-installed rebar connections as a bonding agent between steel reinforcement bars and old concrete under pull out test. The experimental samples were; cylindrical samples of (150 mm dia. × 300 mm high) with anchors rebar of varying diameter (12 and 16 mm), different embedded length (100 and 150) mm with different holes’ diameters. The strategy of control were cast-in-place rebar concrete specimens while other samples are post-installed rebar concrete specimens of varied chemical adhesives as bonding agents, namely KUT EPOXY ANCHOR ‘NS’ and SIKAFLOOR169. The output showed that the different adhesives yielded closed pull-out load values. It is found that the pull-out capacity (bond strength) is increased by increasing the embedded length, the diameter of the rebar and slightly with the diameter of the hole. In addition, the failure mode of post-installed rebar concrete was governed by the embedded length and the area of contact with the adhesives. On the other hand, the larger diameter of rebar favors splitting or failure of concrete due to higher strength in binder-rebar interface compare to the binder-concrete interface. The results showed that the pull-out load was increased by (26 % and 32 %) as the rebar diameter increased from 12 mm to 16 mm for KUT “NS” and SIKAFLOOR respectively. The hole diameter had slightly effect of the pull out load where the average of increment was only 6 %. Finally, the bonding strength is considerably depended on the embedded length and less affected by the type of epoxy.

scholarly journals Immediate Dentin Bond Strength of Self-etch Dentine Adhesives

2014 ◽  
Vol 2 (1) ◽  
pp. 51
Author(s):  
David Lafuente ◽  
Isabel Ferreto
Keyword(s):  
Bond Strength ◽  
Shear Bond Strength ◽  
Statistical Difference ◽  
Composite Resin ◽  
The Other ◽  
Bonding Agents ◽  
Dentin Bonding ◽  
Dentin Surface ◽  
Sixth Generation ◽  
Self Etch

Purpose: The purpose of this study was to evaluate the immediate bond strength of two sixth generation and two seventh generation dentin bonding agents to superficial dentin. Specimens were prepared to exposed superficial dentin and either Clearfil SE, Clearfil S3, Adper Prompt-l-pop of G-bond was applied over the dentin surface and light cured. Then composite resin was applied to the treated surface and light-cured in two increments. Specimens were tested 15 minutes after they were made for shear bond strength at 0.01 cm/min. Clearfil SE had statistically higher bond strength than the other three adhesives evaluated (42.9 MPa). There was no statistical difference among Clearfil S3, Adper Prompt-l-pop and G-Bond. The dentin adhesive with an application of an acidic primer before the application of the adhesive showed better immediate bond strength.

Experimental study of an innovative driven and grouted soil nail (x-Nail)

2020 ◽  
Author(s):  
Mohammad Zahidul Islam Bhuiyan ◽  
Shanyong Wang ◽  
John P. Carter
Keyword(s):  
Experimental Study ◽  
Experimental Investigation ◽  
Bond Strength ◽  
Innovative Design ◽  
Pullout Force ◽  
Soil Nail ◽  
Compaction Grouting ◽  
Pull Out ◽  
High Bond ◽  
High Bond Strength

This paper describes an experimental investigation of a newly developed driven and grouted soil nail (x-Nail), which combines the capabilities of a purely frictional driven nail and a compaction-grouted nail. The innovative design allows the x-Nail to be driven into the ground with a latex balloon attached that is used subsequently for compaction grouting. A grout bulb is thus formed at the driven end of the nail to improve its pull-out resistance. For compaction grouting, a special type of additive-mixed cement grout was used in this investigation because of its zero bleeding and high bond strength. A series of pullout model tests was conducted to examine the performance of the x-Nail compared to a purely frictional soil nail. It was found that more than 90% of the pullout force of the x-Nail was resisted by the expanded grout bulb and the end bearing resistance of the grout bulb increased with the increment of the injected grout volumes. The experimental results revealed that the pullout force of the x-Nail increased approximately 1800%, 1550%, 1200% and 900% compared to the purely frictional soil nail for the injected grout volumes of about 350 ml, 270 ml, 220 ml, and 170 ml, respectively.

Experimental Study on Effects of Fatigue Loading History on Bond Behavior between Steel Bars and Concrete

2016 ◽  
Vol 711 ◽  
pp. 673-680 ◽  
Author(s):  
Zhiwen Ye ◽  
Wei Ping Zhang ◽  
You Hu ◽  
Xiang Lin Gu
Keyword(s):  
Experimental Study ◽  
Bond Strength ◽  
Fatigue Loading ◽  
Critical Value ◽  
Concrete Cover ◽  
Repeated Loading ◽  
Loading History ◽  
Bond Behavior ◽  
Pull Out ◽  
Steel Bars

This paper presents an experimental investigation on the influence of fatigue loading history on bond behavior between steel bars and concrete. Reinforced concrete specimens were subjected to fatigue loadings with different amplitudes and cycles before undergoing eccentric pull-out tests. Tests revealed that all specimens failed with the splitting of the concrete cover. With increased loading cycles, the concrete in front of transverse ribs usually becomes denser at the beginning. Meanwhile, the initial bond stiffness and the bond strength increased, while the slip corresponding to the peak bond stress decreases. With the further increase of loading cycles, the bond strength begins to decrease after it reaches a critical value. This study determined that for specimens subjected to repeated loading with a larger amplitude, fewer cycles are needed for the bond strength to go up to the critical bond strength.

Experimental Study of Bond Behavior on Aluminum Alloy Plate-to-Concrete Interface

2014 ◽  
Vol 501-504 ◽  
pp. 805-810 ◽  
Author(s):  
Ji Hua Zhu ◽  
Liang Liang Wei ◽  
Miao Chang Zhu ◽  
Wei Wen Li ◽  
Feng Xing
Keyword(s):  
Experimental Study ◽  
Aluminum Alloy ◽  
Bond Strength ◽  
Bond Length ◽  
Failure Modes ◽  
Coupling Effect ◽  
Experimental Program ◽  
Alloy Plate ◽  
Aluminum Alloy Plate ◽  
Concrete Interface

This paper presents an experimental study on the bond performance of aluminum alloy plate-to-concrete interface via a series of simple shear test. The parameters examined include the bond length and width of the aluminum alloy plates. Two types of failure modes were observed through the experimental program. The test results demonstrate the bond strength of the aluminum plate-to-concrete interface depends strongly on the coupling effect of bond length and width. The variation of the aluminum strain distribution along the bond length against the applied load clearly illustrates the existence of an effective bond length. The load-slip curves show that the bond width has more sensitive effect to the bond strength.

scholarly journals Numerical analysis of the effect of embedment depth on the geometry of the cone failure

2021 ◽  
Vol 2130 (1) ◽  
pp. 012012
Author(s):  
J Jonak ◽  
R Karpiński ◽  
A Wójcik
Keyword(s):  
Rock Mass ◽  
Fem Analysis ◽  
Potential Interaction ◽  
The Other ◽  
Rock Surface ◽  
Embedment Depth ◽  
Failure Zone ◽  
Pull Out ◽  
Failure Angle ◽  
Anchor Systems

Abstract This paper presents the results of a numerical FEM analysis of the effect of embedment depth on the extent of the failure zone (cone failure) under the effect of an undercut anchor. For the establishment of the other affecting quantities, the formation of the value of the cone failure angle of the rock medium depending on the embedment depth was analysed. The problem is interesting as regards aspects of rock mass loosening during pull-out of undercut anchors. As a result of the analysis, a significant effect of embedment depth on propagation and the extent of cone failure has been found. The increasing value of embedment depth significantly decreases the extent of the failure zone measured on a free rock surface. The increasing value of cone failure angle limits the potential interaction of failure zones in multi-anchor systems.

scholarly journals Experimental Study on Behavior of Shear Connectors Embedded in Steel-Reinforced Concrete Joints

2018 ◽  
Author(s):  
Riko Nakamori ◽  
Yuki Kageyama ◽  
Nozomu Baba
Keyword(s):  
Experimental Study ◽  
Reinforced Concrete ◽  
Bond Strength ◽  
Concrete Member ◽  
Steel Reinforced Concrete ◽  
Shear Connectors ◽  
Reinforced Concrete Member ◽  
Average Maximum ◽  
Concrete Joints ◽  
Concrete Interface

This paper presents an experimental study on the behavior of shear connectors embedded in steel-reinforced concrete joints. In steel-reinforced concrete joints, the shear connectors are commonly used to transfer longitudinal shear forces across the steel-concrete interface. Further, in Japan, some studies in recently have also been undertaken to apply perfobond rib shear connector (PBL), which is a type of shear connectors developed in civil engineering, to the steel-reinforced concrete joints in building structures. To clarify the influence of the arrangement methods of headed studs and PBLs to reinforced concrete member on the joints, T-shaped subassembrages were tested under the monotonic tensil loading.This experiment is constituted of the following; Exp. I: Bond strength across the steel-concrete interface. Exp. II: Arrangement methods of these shear connectors to reinforced concrete member. The following can be drawn from the test results 1) The experimental values of the average maximum and residual bond strength are 0.230-0.280 and 0.15-0.18 N/mm2, respectively. 2) When the distance of between the upper surface of the reinforced concrete member from the first layer for headed studs are small, the failure mode of the specimens is similar to a concrete-cone type failure. 3) In case that the total number of headed studs or the hole provided to PBL is the same, the maximum load of the specimen with the parallel arrangement is larger than that of when shear connecters are vertically arranged. 4) The shear strength of headed studs in the joints embedded the steel member in the reinforced concrete member is estimated by superposing the average residual bond strength across the steel-concrete interface. 

scholarly journals Experimental study on bond performance between GFRP bars and concrete

2020 ◽  
Vol 165 ◽  
pp. 04041
Author(s):  
Fu Decheng ◽  
Wang Bo
Keyword(s):  
Experimental Study ◽  
Bond Strength ◽  
Bond Length ◽  
Concrete Strength ◽  
Bond Failure ◽  
Bond Performance ◽  
Gfrp Bars ◽  
Bonding Performance ◽  
Pull Out ◽  
Gfrp Reinforcement

Based on 27 bonding test of pull-out specimens, the bonding performance between GFRP and concrete was studied systematically. The bond failure between concrete and GFRP includes four stages: microslip stage, linear slip stage, nonlinear slip stage and bond failure stage. The experiment shows that there is no significant correlation between concrete strength and bond strength, bond strength increases with the bond length and decreases with the increase of GFRP reinforcement diameter.

scholarly journals An Experimental Study on Effects of Corrosion and Stirrups Spacing on Bond Behavior of Reinforced Concrete

Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1327
Author(s):  
Konstantinos Koulouris ◽  
Charis Apostolopoulos
Keyword(s):  
Experimental Study ◽  
Reinforced Concrete ◽  
Bond Strength ◽  
Mass Loss ◽  
Corrosion Damage ◽  
Ongoing Research ◽  
Average Width ◽  
Concrete Cracking ◽  
Bond Behavior ◽  
Pull Out

The current experimental study consists of part of an extensive and ongoing research on bond behavior of RC elements damaged by corrosion, focusing on stirrups spacing effect on bonding. For this, RC specimens with different cases of stirrups spacing were casted. Accelerated corrosion was induced in order to simulate the slow process of nature corrosion on RC specimens and the corrosion damage was estimated in terms of mass loss of steel bars and average width of surface concrete cracking. Subsequently, pull-out tests were carried out to examine the bonding resistance between steel and concrete. The study indicates the great influence of density of stirrups on the percentage mass loss of the embedded reinforcing bar, accompanied by width of surface concrete cracking, as well as on bond strength between steel and concrete. The results of bond stress–slip curves show that the densification of stirrups plays a significant role in bonding, leading to higher bond strength values and delaying the degradation of bond loss as corrosion damage increases. However, it becomes apparent that, although the densification of stirrups (Φ8/60 mm) result in the full anchorage of steel-reinforcing bars, it may be inappropriate, since it can lead to a substantial increase in costs and a rapid rise in corrosion rate, due to potential increase. Furthermore, the recorded values of relative slip at bond strength are between 1 and 3 mm, regardless of corrosion damage or concrete cracking, which depends on the ribs geometry and crushing of concrete in front of them. To conclude, the results of the present manuscript indicate that the increase in transverse reinforcement (stirrups) percentage plays a key role in the durability of reinforced concrete elements and in bond strength maintenance between rebar and concrete.

Influence of Curing Agents on Rubber-to-Textile and Rubber-to-Steel Cord Adhesion

1973 ◽  
Vol 46 (4) ◽  
pp. 981-998 ◽  
Author(s):  
K.-D. Albrecht
Keyword(s):  
The Other ◽  
Complete Wetting ◽  
Bonding Agents ◽  
Pull Out ◽  
Steel Cord ◽  
Sulfur Level ◽  
Curing Agents ◽  
Reinforcing Material ◽  
Heat History ◽  
Pull Out Strength

Abstract The results presented in this paper show that the dosage of sulfur greatly influences rubber-to-textile and rubber-to-steel cord adhesion. As far as rubber-to-textile adhesion is concerned, the pull-out strength is reduced when the sulfur level falls below 2 phr, the extent of the reduction depending on the type of fiber and the bonding process. With steel cord the lower limit for sulfur is as high as 3 phr. This is discouraging because it shows that the use of efficient and semi-efficient vulcanization in the manufacture of goods reinforced with fabrics or steel cord is, to say the least, highly problematical. On the other hand, it is often desirable to reduce the proportion of sulfur in order, for instance, to increase resistance to aging and reversion and to reduce compression set and heat build-up. The choice of accelerators also has an important influence on adhesion. A sufficiently long scorch time is required to allow complete wetting of the reinforcing material by the rubber compound. If curing starts before complete wetting of the textile or steel cord has occurred, adhesion cannot be built up. For example, unsatisfactory or no rubber-to-textile and rubber-to-steel cord adhesion is obtained, when ultra-accelerators are used. As the scorch time increases, adhesion improves. Best results are obtained with sulfenamides, but sulfenamides showing increasing scorch time give no improvement in rubber-to-textile bonding. However, DCBS gave much better results for rubber-to-steel cord adhesion than the other sulfenamides and thus appears particularly suitable. Although the results given by the other sulfenamides can be somewhat improved by the addition of a retarder, pull-out strength values do not reach those given by DCBS. Any decrease of scorch time of a compound deteriorates adhesion whether scorch time is reduced by compounding ingredients or by heat history imposed by processing. MBI, used as an antioxidant, which reduces scorch time drastically, causes complete loss of rubber-to-steel cord adhesion and also impairs rubber-to-textile adhesion. Most of the antioxidants, however, have a beneficial effect on mbber-to-steel cord adhesion. For zinc-plated steel cord antioxidants of the amine type give results inferior to those of the phenolic type. To obtain optimal rubber-to-textile and rubber-to-steel cord adhesion the compounder primarily has to consider the efficacy of the bonding agents but in addition he has to take into account the effects which may be exerted by compounding ingredients and processing conditions.

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