scholarly journals Experimental Study on the Effectiveness of Inorganic Bonding Materials for Near-Surface Mounting Shear Strengthening of Prestressed Concrete Beams

Fibers ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 40
Author(s):  
Vikas Singh Kuntal ◽  
M. Chellapandian ◽  
S. Suriya Prakash ◽  
Akanshu Sharma
Keyword(s):  
Bond Strength ◽  
Epoxy Resin ◽  
Prestressed Concrete ◽  
High Strength ◽  
Cement Grout ◽  
Shear Strengthening ◽  
Near Surface ◽  
Pull Out ◽  
Surface Mounting ◽  
Bond Tests

Use of organic resins such as epoxy and vinyl esters as bonding materials in fibre reinforced polymer (FRP) strengthening of concrete members is widely accepted. However, the performance of organic resins is compromised when exposed to high temperature and extreme weather conditions leading to reduced durability of the strengthened systems. The present study attempts to evaluate the effectiveness of inorganic (cement mortar and geopolymer mortar) bonding materials for shear strengthening of prestressed concrete (PSC) beams using the near-surface mounting (NSM) technique. Different types of bonding materials are used in this study for NSM shear strengthening including: (i) epoxy resin, (ii) high strength cement grout (HSCG) and (iii) geopolymer mortar. Bond tests were first conducted to evaluate the pull-out/bond strength of different bonding materials. Bond tests revealed that epoxy resin had the highest bond strength followed by geopolymer mortar and HSCG. Sixteen full-scale PSC beams were cast with and without stirrups. The beams were strengthened using NSM CFRP laminates oriented at 45-degree configuration and then tested under a three-point bending configuration. Experimental results revealed that the performance of high strength cement grout and geopolymer mortar was similar but with a lesser efficiency compared to the epoxy resin.

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.

Utilization of Waste Packaging Glass as Progressive Filler in Polymer Anchor Material Based on Epoxy Resin

2019 ◽  
Vol 887 ◽  
pp. 40-47
Author(s):  
Tomáš Žlebek ◽  
Jakub Hodul ◽  
Rostislav Drochytka
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Epoxy Resin ◽  
High Strength Concrete ◽  
Chemical Resistance ◽  
Negative Impact ◽  
High Strength ◽  
Pull Out ◽  
Pull Out Strength ◽  
Packaging Glass

The work deals with the use of waste glass to the polymer anchor material based on epoxy resin, primarily for anchoring to a high strength concrete (HSC). The main aim was to use the largest possible amount of the waste packaging glass by reducing the amount of epoxy resin, which is an expensive material and its production has a negative impact on the environment. Within the experimental verification, the influence of waste packaging glass fraction 0–0.63 mm on the final properties of the polymer anchoring material was observed. To determine the optimal formulation compressive strength, flexural strength, chemical resistance, shrinkage and pull-out test were performed. Based on the evaluation of the results the optimal percentage of filling was determined, when the polymer anchor material showed high strengths, minimal shrinkage, good chemical resistance, optimal consistency for anchoring into the HSC and high anchor bolt pull-out strength.

Stretch Formability Behaviour of Glass Fibre Reinforced Nanoclay on Fiber Metal Laminated Composites

2018 ◽  
Vol 10 (2) ◽  
Author(s):  
K. Logesh ◽  
V.K Bupesh Raja ◽  
C. Krishnaraj
Keyword(s):  
Ductile Fracture ◽  
Epoxy Resin ◽  
Glass Fibre ◽  
Weight Ratio ◽  
High Strength ◽  
Core Material ◽  
Fibre Metal Laminates ◽  
Sem Image ◽  
Pull Out ◽  
Fibre Metal

Innovations and research in material processing have brought forward new and improvised materials that are applied in body panels of automobiles, aircraft cabins and railway wagons. These materials are used widely is because of their good mechanical properties and their high strength to weight ratio. In this paper Fibre Metal Laminates (FMLs) were added with organo modified montmorillonite (MMT) commonly known as nanoclay along with epoxy resin. The homogeneous dispersion of nanoclay in epoxy resin is accomplished by a hand stirrer dispersion method in ethanol. The FML material was processed by hand layup method. In this study the aluminium alloy 5052-H32 was used as a skin material and glass fibre (woven roving) used as core material which is bounded by epoxy with 5 wt.% nano clay (closet 30B). The fabricated sandwich material was cut by using water jet machine as per IS standards for testing. The fabricated material subjected to erichsen cupping test and was observed under Scanning Electron Microscope (SEM). The results from SEM image analysis indicated that the FML had fibre pull out and surface cracks were obtained in the skin material. Progressive loading resulted in ductile fracture which is absorbed in the specimen. Fibres came across brittle failure and the skin through ductile fracture. Non-uniform distribution of reinforcement is observed in the material, SEM micrographs revealed fibre cracks which were oriented in line to the direction of crack growth on the skin material. This study shows that these fibre metal laminates can be safely applied in automotive field.

Bond Index Numbers of Prestressed Concrete Reinforcement Wires and Their Relationships to Transfer Lengths and Pull-Out Forces

2016 ◽  
Author(s):  
Mark D. Haynes ◽  
Chih-Hang John Wu ◽  
Matthew Arnold ◽  
Naga Narendra B. Bodapati ◽  
B. Terry Beck ◽  
...  
Keyword(s):  
Bond Strength ◽  
Mathematical Models ◽  
Surface Area ◽  
Prestressed Concrete ◽  
Transfer Length ◽  
Bond Index ◽  
Concrete Members ◽  
Pull Out ◽  
Geometrical Features ◽  
Insight Into

The purpose of this research is to establish mathematical models that predicts the bond strength of a reinforcement wire in prestressed concrete members, given the known geometrical features of the wire. A total of nineteen geometrical features of the reinforcement wire were measured and extracted by a precision non-contact profilometer. With these mathematical models, prestressing reinforcement wires can now be analyzed for their bond strength without destructive testing. These mathematical models, based upon a large collection of empirical data via prestressing reinforcement wires from various wire manufacturers in US and Europe, have the potential to serve as quality assessment tools in reinforcement wire and prestressed concrete member production. Most of these models are very simple and easy to implement in practice, which could provide insight into which reinforcement wires provide the greatest bond strength and which combinations of geometrical features of the reinforcement wire are responsible for providing the bond strength. Our various empirical models have shown that the indent side-wall angle, which is suggested by the ASTM-A881/A881M, may not be the only significant geometrical feature correlated to the transfer length and bond strengths. On the contrary, features such as the indent surface area, indent width, indent edge surface area, indent volume, and release strengths do have significant correlations with the ultimate transfer lengths of the prestressed concrete members. Extensive experiments and testing performed at the Structures Laboratory in Kansas State University, as well as field tests at Transportation Technology Center, Inc. (TTCI) and one Prestressed Concrete Railroad Tie manufacturing facility, have been used to confirm the model predictions. In addition, our experimental results suggest that the maximum pull out force in the un-tensioned pullout testing has significant correlation with the ultimate transfer length. This finding could provide reinforcement wire manufactures with a quality assurance tool for testing their wires prior to the production. The resultant mathematical model relating the wire geometrical features to transfer length is referred to as the Bond Index Number (BIN). The BIN is shown to provide a numerical measure of the bond strength of prestressing steel reinforcement wire, without the need for performing destructive tests with the reinforcement wire. We believe that with the BIN and the maximal pull-out forces from the un-tensioned pull-out tests, one can have better insight into the optimal reinforcement wire design by testing the performance of wires before they are put into production lines.

BOND STRENGTH RECOVERY OF FIRE-DAMAGED CONCRETE AFTER POST-FIRE-CURING

2015 ◽  
Vol 2 (1) ◽  
Author(s):  
Zhuguo Li ◽  
Yasuhiro Ryuda
Keyword(s):  
Bond Strength ◽  
High Strength ◽  
Test Results ◽  
Strength Concrete ◽  
Pull Out ◽  
Strength Recovery ◽  
Steel Bars ◽  
Bond Strengths ◽  
Normal Strength ◽  
Curing Age

The effects of post-fire-curing on the bond strength recovery of fire-damaged concrete were investigated in this study. Normal strength concrete (NSC) and high-strength concrete (HSC) specimens with deformed steel bars were prepared respectively. We measured the bond strength of unheated NSC and HSC, and exposed other NSC and HSC specimens to high temperatures of 300℃, 400℃, and 500℃, respectively for 120 minutes. Following by rapid cooling with water, the bond strengths of heated NSC and HSC were measured instantly without re-curing, the remains were cured in water for 28 days, or further in the air of 20℃, 60% R.H. for 56 ~62 days. After the re-curing, the pull-out tests were conducted. The test results indicate that the post-fire-curing contributes to a substantial bond strength recovery of heated concrete. The longer the re-curing in water, the greater the recovery extent. At 90 days of re-curing age, the bond strength rose up to around 77% for NSC, and around 70% for HSC, respectively.

scholarly journals Characterisation of the Interfacial bond Strength between Glass Fibre and Epoxy Resin using the Pull-Out and Push-Out Techniques

2000 ◽  
Vol 9 (3) ◽  
pp. 096369350000900 ◽  
Author(s):  
E. Mδder ◽  
X.-F. Zhou ◽  
E. Pisanova ◽  
S. Zhandarov ◽  
S. R. Nutt
Keyword(s):  
Bond Strength ◽  
Epoxy Resin ◽  
Glass Fibre ◽  
Critical Energy ◽  
Interfacial Bond ◽  
Interfacial Bond Strength ◽  
Critical Energy Release Rate ◽  
Pull Out ◽  
Loading Patterns ◽  
Push Out

Interfacial bond strength between epoxy resin and glass fibre was studied using the pull-out and push-out techniques. For untreated fibres, these micromechanical tests gave similar values of the local interfacial shear strength and critical energy release rate. In the case of fibres treated by γ-APS, both tests showed considerable increase in the bond strength. However, for the modified fibres, the pull-out test gave greater values of both interfacial parameters than the push-out test, a result attributed to the different modes of interfacial loading. The different loading patterns also cause different failure mechanisms in these two tests.

Evaluation of Bond Strength between Steel Fiber Reinforced Ultra-High Strength Concrete and Rebar

2015 ◽  
Vol 665 ◽  
pp. 41-44
Author(s):  
B.I. Bae ◽  
Hyun Ki Choi ◽  
Chang Sik Choi
Keyword(s):  
Bond Strength ◽  
High Strength Concrete ◽  
Steel Fiber ◽  
High Strength ◽  
Fiber Reinforced ◽  
Strength Concrete ◽  
Pull Out ◽  
Reinforced Concrete Member ◽  
Significant Difference ◽  
Cover Thickness

In order to design reinforced concrete member using steel fiber ultra high strength concrete, current structural design methods should be re-evaluated because it has significant difference in material characteristics compared with normal concrete. In this study, bond strength of steel fiber reinforced ultra-high strength concrete was evaluated. For this purpose, direct pull out test specimens were constructed with variables of cover thickness, compressive strength of matrix and fiber inclusion ratio. According to the test, bond strength were sensitively varied with cover thickness and fiber inclusion. Because bond strength was determined by tensile strength of concrete. Comparing test results with theoretical methods suggested by Tepfers, specimens without steel fiber show good agreement with analytical method, because this method were based on elasticity. And other empirical equations were evaluated with other previous researches.

An Experimental Study on the Strengthening Performance of RC Beams Reinforced by NSM CFRP Tendon According to the Surface Treatment of Tendon

2017 ◽  
Vol 730 ◽  
pp. 435-439
Author(s):  
Woo Tai Jung ◽  
Moon Seoung Keum ◽  
Jae Yoon Kang ◽  
Jong Sup Park
Keyword(s):  
Bond Strength ◽  
Surface Treatment ◽  
Concrete Beams ◽  
Rc Beams ◽  
Flexural Test ◽  
Near Surface ◽  
Bond Performance ◽  
Structural Reinforcement ◽  
Pull Out ◽  
Near Surface Mounted

This study evaluates the bond performance of the CFRP tendon through pull-out test and investigates experimentally the strengthening performance according to the eventual surface treatment of the tendon on concrete beams strengthened by near-surface mounted (NSM) tendon. The pull-out test revealed that the bond strength was improved by 3 times when surface treatment was applied to the tendon. In addition, similar improvement of the bond performances was observed regardless of the execution time of the surface treatment being manually on site or at the factory during the production of the tendon. The flexural test showed that the surface treatment of the CFRP tendon improved the strengthening performance by 13%. Consequently, when using the CFRP tendon featured by low bond strength, it appears that structural reinforcement can be improved by executing beforehand surface treatment of the tendon on site.

scholarly journals Cementitious adhesives for NSM carbon laminate strengthening system with treated surfaces

2019 ◽  
Author(s):  
Reza Mohammadi Firouz ◽  
Eduardo B. Pereira ◽  
Joaquim A. O. Barros
Keyword(s):  
Bond Strength ◽  
Structural Composites ◽  
Near Surface ◽  
Pull Out ◽  
Good Ability ◽  
Near Surface Mounted ◽  
Rapid Restoration ◽  
Pre Treatment ◽  
Strengthening Technique ◽  
In Fire

<p>One of the main concerns of using structural composites as an effective technique for strengthening and rapid restoration of concrete structures is the behaviour of these systems in fire condition. Epoxy resins are currently used to bond structural composites to concrete substrate, but the vulnerability of their properties to high temperatures can compromise the strengthening effectiveness of these systems. Hence, finding an alternative adhesive is of a great importance. Recent studies presented promising results with the use of cement based materials as adhesives due to their good ability for transferring stresses and compatibility to the substrate. This study explores the adoption of a pre-treatment procedure for carbon fibre laminates for increasing the bond strength according to the near surface mounted (NSM) strengthening technique. Pull-out tests results confirmed the effectiveness of the proposed approach for enhancing the bond strength.</p>

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