Effects of Corrosion and Bar Splicing on Bond Properties of Deformed Reinforcing Bars in Concrete PDF Download

Author: Kamran Farhadi
Publisher:
ISBN:
Category : Reinforced concrete construction
Languages : en
Pages : 216

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Author: Mehdi Ghaffarzadeh
Publisher:
ISBN:
Category : Reinforcing bars
Languages : en
Pages : 187

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Author: Weldon W. Aldridge
Publisher:
ISBN:
Category : Corrosion and anti-corrosives
Languages : en
Pages : 230

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Author: ACI Committee 440
Publisher:
ISBN: 9780870311185
Category : Fiber-reinforced concrete
Languages : en
Pages : 42

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Book Description

Author: J. Tonini
Publisher: ASTM International
ISBN: 9780803103160
Category : Science
Languages : en
Pages : 216

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Book Description

Author: D. E. Tonini
Publisher:
ISBN:
Category : Concrete
Languages : en
Pages : 220

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Book Description

Author: Leroy Albert Lutz
Publisher:
ISBN:
Category : Reinforced concrete construction
Languages : en
Pages : 654

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Author: Konstantinos Koulouris
Publisher:
ISBN:
Category : Electronic books
Languages : en
Pages : 0

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Book Description
This chapter is devoted to the effects of steel corrosion on bond relationship between steel and concrete. One of the basic assumptions in design of reinforced concrete members is the perfect steel - concrete bond mechanism, so that strain of reinforcing bar is the same as that of the surrounding concrete and these two different materials act as one. However, corrosion of steel reinforcement consists one of the main durability problems in reinforced concrete members, downgrade the bond behavior and therefore their structural integrity. Corrosion degrades the reinforcement itself, reducing the initial cross-section of the steel bar and its mechanical properties. Furthermore, tensile stresses in surrounding concrete caused due to oxides on the corroded reinforcement, lead to the gradual development of tensile field to the surrounding concrete, with spalling of the cover concrete and loss of bond mechanism as a consequence. In this chapter, an overview of damage of reinforced concrete due to steel corrosion is given, focused on the bond mechanism; factors that play key role in the degree of bonding and, also, proposed models of bond strength loss in correlation with the surface concrete cracking due to corrosion are indicated. To conclude, the ongoing research in this area of interest is presented, based on recent scientific studies.

Author: Ghassan Khaled Jumah
Publisher:
ISBN:
Category : Deformations (Mechanics)
Languages : en
Pages : 174

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The theory of reinforced concrete is based on stress transfer between steel and concrete. In order for the steel to develop its full yield force in tension, there should be some bond between that steel and the surrounding concrete. With the deformed bars, used in reinforced concrete construction since many decades, the problem of bond was the topic for many research programs dedicated for the investigation of the factors influencing that bond, Some of these factors are : bar size, cover thickness, spacing between embedded bars, and deformation properties of the bar itself. The objective of our research work was to investigate the effect of rib geometry or rib deformation properties on the bond-slip characteristics of deformed reinforcing bars. For that purpose, plain round Grade 60 bars 20.6 mm (0.811 in.) in diameter were machined to simulate #6 bars. Fifty six of these test bars were tested in eccentric pullout tests. The specimen was a concrete block with a 10-in. length and a 12in.xl2in. cross section. The bar was embedded along the 10-in. length and was loaded in tension until failure of the specimen in a V-notch splitting mode, where the test was halted. Such a short embedment length (10 in.^ for the test bar was chosen in order to avoid yielding of the bar and to minimize the difference in tensile stresses between the loaded-end and the free-end of the bar. The load and the free-end slip of the bar was monitored during the test. Seven series of pullout specimens were prepared and tested, and replicates were included to check the reliability of the test setup and the obtained results. In series ONE and FOUR, the main variable was the rib face angle where five rib face angles were investigated, 30, 45, 60, 75, and 90 degrees. The concrete compressive strength in series ONE was 3000 psi while in series SIX, it was 6000 psi. The main variable in series TWO and FIVE was the rib spacing. Five values of rib spacings were investigated, 0.3 in. (0.37 db), 0.35 in. (0.43 dO, 0.4 in. (0.49 db), 0.45 in. (0.55 db), and 0.5 in. (0.62 db). The rib height was investigated in series THREE and SIX with two different concrete compressive strengths, 3000 and 6000 psi respectively. Four values of rib heights were investigated; 0.04 in. (0.05 db), 0.06 in. (0.074 db), 0.08 in. (0.1 db), and 0.1 in. (0.124 db). Based on the test results of the first six series, the values for the variables in the seventh series were decided upon. In this last series, the rib spacing was kept constant and equal to 0.4 in. (0.49 db), and four combinations of rib face angles and rib heights were tested. The first two combinations had a rib face of 45 degrees and two different rib heights, 0.06 in. (0.074 db) and 0.08 in. (0.1 db), while the other two had a rib face angle 60 degrees with two different rib heights, 0.06 in. (0.074db) and 0.08 in. (0.1 db).

Author: Sourav Khatua
Publisher:
ISBN:
Category : Adhesives
Languages : en
Pages :

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Book Description
Corrosion of steel reinforcing bars embedded in concrete applications is a major problem all over the world. Effect of corrosion causes metal loss at sections, cracks in the concrete surrounding the reinforcing steel, spalling of cover concrete also leads to de-bonding of reinforcing bar from the concrete. Corrosion cracks in the surrounding concrete leads to loss in bond strength and finally reduce the structural strength and service life of the structure. This problem is consistently observed in structural slab bridges that are exposed to deicing salts during the winters. In the era of 1980's, black convention steel was replaced with epoxy-coated bars as a solution to prevent corrosion in bridge decks. However the advantage of using epoxy coated bars is still uncertain as the bond strength of these type of bars is a concern. Several researchers in the past have highlighted deleterious effect of corrosion on epoxy-coated bars that are damaged during handling. It is necessary to study the use of alternative reinforcing bars as means of corrosion protection in bridge deck applications. There are several corrosion resistant bars that are readily available in the market, but performance of these bars under accelerated corrosion conditions is still unclear. Six different types of bars which include, conventional black bars, epoxy-coated bars, hot dipped galvanizing bars, continuously galvanized bars, stainless steel bars and MMFX bars were studied in this thesis. The objective of this study is to investigate the effect of accelerated corrosion on bond strength of concrete. The bond between concrete and reinforcement bars play a major role in transfer of stresses from concrete to steel. However, corrosion weakens this bond, resulting in weakening of the Reinforced Concrete member. So, it was necessary to investigate the performance of CRR (Corrosion Resistant Bars) embedded in concrete and s ubjected to accelerated corrosion. The effect of addition of polypropylene fibers on the bond strength was studied. A total of 48 prism specimens were cast with CRR bars including the ones with fibers, of which 24 specimens were subjected to accelerated corrosion. The prisms were 6-inch cube with a reinforcing bar at the centre of each specimen. The embedment length of the bar was 2.5 inches at the mid-height of the section. An electrochemical cell was adopted by placing the specimens in a tank containing 5% salt solution with stainless steel cathode surrounding the specimen. The circuit was completed by connecting the cathode and the reinforcing bar to an external power supply. The specimens were subjected to accelerated corrosion for total of 21 days which includes a two-day wetting and one day drying cycle. Impressed current of 0.02A, calculated using Faraday's law to achieve 5% corrosion damage was supplied during the wetting cycle using external power source. The corroded specimens were then tested to investigate the loss of bond strength due to corrosion and capture any improvement in bond strength using polypropylene fibers. It was observed that, corrosion of bars showed serious bond loss leading to reduced pull-out strength with larger slip of the bars relative to the embedded concrete prisms. Addition of polypropylene fibers showed an improvement in the overall performance of the corroded specimens by increasing the load capacity, reducing slip and improving failure mode from brittle to more ductile mode, compared to un-corroded specimens..