scholarly journals Optimization of the effect of corrosion on bond behaviour between steel and concrete

2021 ◽  
Author(s):  
Zahir Aldulaymi
Keyword(s):  
Compressive Strength ◽  
Bond Strength ◽  
Laboratory Study ◽  
Crack Width ◽  
Electrochemical Corrosion ◽  
Pullout Test ◽  
Concrete Cover ◽  
Bond Stress ◽  
Chloride Ingress ◽  
Four Levels

This research program consists of laboratory study of corrosion phenomenon in reinforced concrete and further analytical study of the experimental results obtained by Amleh (2000). The laboratory study examined the influence of increasing levels of corrosion on the progressive deterioration of bond between the steel and concrete and determined the extent to which the various water to cement (w/c) ratio in concrete mixtures influence the corrosion of the steel reinforcement as well as the chloride ion penetration. The influence of corrosion on the bond characteristics of the reinforcing bars in pullout test specimens made with two different w/c ratios and two different concrete cover thicknesses were investigated using control specimens to study the effect of the concrete cover ratio and the concrete compressive strength. The two w/c ratios were 0.47 and 0.37, with two concrete cover thicknesses of 40 mm and 65 mm. Hence, the effect of w/c ratio on different parameters like rate of corrosion, compressive strength and the effect of concrete cover thickness on the corrosion rate were studied. An accelerated electrochemical corrosion procedure was used to develop four levels of corrosion including no corrosion to complete corrosion, with over 25 percent steel bar weight loss due to corrosion, with wide longitudinal cracks. This research study clearly indicated that the bond stress-slip response of the embedded bar in the pullout specimen, was adversely affected by the width of the crack, and the level of corrosion. The crack width was found to develop faster and longer in specimens with lower compressive strength and as a result the maximum bond strength in the pullout test is affected signifcantly by the number and size of cracks, and thus, the level of corrosion. For a given crack width due to corrosion, it is observed that the available bond strength is higher for larger concrete cover thicknesses than for smaller cover thicknesses. Certainly, the quality of concrete in terms of its permeability is equally important for the corrision protection. A relationship between the effect of w/c ratio on chloride ingress was developed to count for the deterioration in bond stress, and the induced current used in corroding the speciments of Amleh (2000) and of this investigation program were incorporated to consider for the lack of chloride lot content measured due to the shorter immersing time in this investigation and the high current used to force the specimens to corrode in the accelerated corrosion process.

scholarly journals Optimization of the effect of corrosion on bond behaviour between steel and concrete

2021 ◽  
Author(s):  
Zahir Aldulaymi
Keyword(s):  
Compressive Strength ◽  
Bond Strength ◽  
Laboratory Study ◽  
Crack Width ◽  
Electrochemical Corrosion ◽  
Pullout Test ◽  
Concrete Cover ◽  
Bond Stress ◽  
Chloride Ingress ◽  
Four Levels

This research program consists of laboratory study of corrosion phenomenon in reinforced concrete and further analytical study of the experimental results obtained by Amleh (2000). The laboratory study examined the influence of increasing levels of corrosion on the progressive deterioration of bond between the steel and concrete and determined the extent to which the various water to cement (w/c) ratio in concrete mixtures influence the corrosion of the steel reinforcement as well as the chloride ion penetration. The influence of corrosion on the bond characteristics of the reinforcing bars in pullout test specimens made with two different w/c ratios and two different concrete cover thicknesses were investigated using control specimens to study the effect of the concrete cover ratio and the concrete compressive strength. The two w/c ratios were 0.47 and 0.37, with two concrete cover thicknesses of 40 mm and 65 mm. Hence, the effect of w/c ratio on different parameters like rate of corrosion, compressive strength and the effect of concrete cover thickness on the corrosion rate were studied. An accelerated electrochemical corrosion procedure was used to develop four levels of corrosion including no corrosion to complete corrosion, with over 25 percent steel bar weight loss due to corrosion, with wide longitudinal cracks. This research study clearly indicated that the bond stress-slip response of the embedded bar in the pullout specimen, was adversely affected by the width of the crack, and the level of corrosion. The crack width was found to develop faster and longer in specimens with lower compressive strength and as a result the maximum bond strength in the pullout test is affected signifcantly by the number and size of cracks, and thus, the level of corrosion. For a given crack width due to corrosion, it is observed that the available bond strength is higher for larger concrete cover thicknesses than for smaller cover thicknesses. Certainly, the quality of concrete in terms of its permeability is equally important for the corrision protection. A relationship between the effect of w/c ratio on chloride ingress was developed to count for the deterioration in bond stress, and the induced current used in corroding the speciments of Amleh (2000) and of this investigation program were incorporated to consider for the lack of chloride lot content measured due to the shorter immersing time in this investigation and the high current used to force the specimens to corrode in the accelerated corrosion process.

scholarly journals Experimental study on the effect of concrete strength and corrosion level on bond between steel bar and concrete

2021 ◽  
Vol 72 (4) ◽  
pp. 498-509
Author(s):  
Vuong Doan Dinh Thien ◽  
Hung Nguyen Thanh ◽  
Hung Nguyen Dinh
Keyword(s):  
Compressive Strength ◽  
Bond Strength ◽  
Concrete Strength ◽  
Concrete Block ◽  
Bond Stress ◽  
Concrete Compressive Strength ◽  
Pull Out ◽  
Steel Bar ◽  
Stress Degradation ◽  
Slip Displacement

Corrosion of the steel reinforcement bars reduces the area of the steel bar and the bond stress between the steel bars and around concrete that decreases the capacity of concrete structures. In this study, the bond stress between steel bar with a diameter of 12mm and concrete was examined with the effect of different corrosion levels and different concrete grades. A steel bar was inserted in a concrete block with a size of 20×20×20cm. The compressive strength of concrete was 25.6MPa, 35.1MPa, and 44.1MPa. These specimens were soaked into solution NaCl 3.5% to accelerate the corrosion process with different corrosion levels in the length of 60mm. The pull-out test was conducted. Results showed that the bond strength of the corroded steel bar was higher than that predicted from CEB-FIP. Slip displacement and the range of slip displacement at the bond strength were reduced when the concrete compressive strength was increased. The rate of bond stress degradation occurred faster with the increment of the corrosion level when the concrete compressive strength was increased.

The Effect of Wire Type on Cracking Propensity in Prestressed Concrete Prisms

2019 ◽  
Author(s):  
Adrijana Savic ◽  
B. Terry Beck ◽  
Aref Shafiei Dastgerdi ◽  
Robert J. Peterman ◽  
Kyle Riding ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Crack Length ◽  
Cross Section ◽  
Crack Width ◽  
Concrete Cover ◽  
State University ◽  
Qualification Test ◽  
Cement Ratio ◽  
Dead End ◽  
Kansas State University

This paper is a continuation of a previous study conducted at Kansas State University [8]. This paper demonstrates the influence of the thickness of concrete cover, compressive strength of concrete and the type of wire indentation on bond performance between steel and concrete in pre-stressed concrete ties using a consistent concrete mixture. A key objective of this research is to find the best parameters for pre-stressed concrete ties to prevent them from splitting/cracking in the field. This is very important for pre-stressed manufacturers, and especially for the railroad crosstie industry, so as to avoid failures in the field. The goal is to develop a qualification test with the capability to identify the compatible combinations of wire type and concrete mix before the ties are manufactured. A study took place at Kansas State University to understand and quantify the influence of variables such as the thickness of concrete cover, type of indents, and the compressive release strength on the bond behavior between steel and concrete. For the experimental testing three prisms with different cross sections were cast at the same time in series. Four pre-stressing wires were symmetrically embedded into each concrete prism and the spacing between wires was 2.0 inches. All prisms had the same length of 59.5in with square cross section. With the thickness of concrete cover of 3/4″ the first prism had a 3.5×3.5in square cross section, the second prism had a 5/8″ thickness of concrete cover and 3.25×3.25in square cross section and the third prism had a 1/2″ thickness of concrete cover and a 3.0×3.0in square cross section. All pre-stressing wires which were used in these tests had a 5.32mm diameter and were of different wire types. The indent pattern variations of the wire types included spiral, classical chevron shape, and the extreme case of smooth wire with no indentations. The wires were initially tensioned to 7000 pounds (31.14 KN) and then gradually de-tensioned after reaching the desired compressive strength. The different compressive (release strength) strength levels tested included 4500 psi (31.03 MPa) and 6000 psi (41.37 MPa). For this study, a consistent concrete mixture with 0.32 water-cement ratio was used for all prisms, except for prisms casted with WE wire. For these prisms a water-cement ratio of 0.38 was used. Prisms had almost identical geometrical and mechanical properties as pre-stressed concrete ties which are manufactured in the railroad industry. Each prism provided a sample of eight different independent splitting tests of concrete cover (four wire cover tests on each end) for a given release strength. All cracks which appeared after de-tensioning were observed and measured to identify the cracking field, and all sides of the prisms on the live and dead end were marked for identification. For all prisms, longitudinal strain profiles on the live end and dead end were measured along with the values of transfer lengths. The strain profiles were taken using an automated Laser-Speckle Imaging (LSI) system. All results, representing quantitative and qualitative assessment of cracking behavior, are given in this paper as a function of thickness of concrete cover and release strength of concrete. For each sample prism, crack length and crack width were measured, and crack area was calculated as a simple function of crack length and crack width. In the case where spalling occurred, the crack width used was arbitrary set at 0.2in. These tests reveal the influence of thickness of concrete cover, the indented wire type and the release strength of concrete on the bond between steel and concrete. This work represents a successful first step in the development of a qualification test to ensure adequate splitting resistance in pre-tensioned concrete railroad ties.

scholarly journals THE BOND STRENGTH OF STEEL BAR BASE ON RIB GEOMETRY BAR IN PULLOUT TEST

2021 ◽  
Vol 30 (1) ◽  
Author(s):  
Anis Rosyidah ◽  
Johannes Adhijoso Tjondro ◽  
I Ketut Sucita
Keyword(s):  
Bond Strength ◽  
Pullout Test ◽  
Bond Stress ◽  
Failure Pattern ◽  
Bond Index ◽  
Steel Bar ◽  
Study Results ◽  
Concrete Cube

This experiment's objective is to prove that the reinforcing rib's form contributes to its bond strength. The specimen is the concrete cubes measuring 150 × 150 × 150 mm; bar installed in the center of the concrete cube. Bars use 13, 16, and 19 mm diameters. For comparison, the experiment was also carried out on plain reinforcement diameter with 12 mm, 16 mm, and 19 mm. Concrete compression is fc' 34 MPa. The pullout test was also performed to increase the load in stages at a 200 kg/minute speed. Loading stopped if the reinforcement yielded, split concrete, or slipped bar. The experiment uses ASTM standards ASTM C234-91a. The study results are the bond strength on reinforcement with the surrounding concrete. Bond strength in the plain bar is lower than deformed. The reinforcement of steep rib compared to fishbone bond strength values incline to be the same. The ratio of the bond strength of plain compared to deformed is 15% - 18%. The bond index of the steep rib and fishbone rib between 0.11 - 0.16 so that the bond stress obtained is also relatively the same. The failure pattern that occurs is determined based on the bond stress-slip graph. There are two types of collapse in this experiment, namely pullout and splitting damage. The failure of each specimen based on the diameter and shape of the rib varies greatly. The splitting damage is seen visually only in the specimen of the D19 fishbone rib.

Review on Experimental Study on Effect of Corrosion In Reinforced Concrete Fly-Ash Beam

2020 ◽  
pp. 92-96
Author(s):  
Shubham N. Dadgal ◽  
Shrikant Solanke
Keyword(s):  
Fly Ash ◽  
Bond Strength ◽  
Structural Damage ◽  
Pullout Test ◽  
Partial Replacement ◽  
Structural Members ◽  
Accelerated Corrosion ◽  
Resistivity Method ◽  
Electrical Resistivity Method ◽  
Structural Failures

In modern days for structures in coastal areas it has been observed that the premature structural failures are occurs due to corrosion of the reinforcements of the designed structural member. The corrosion causes the structural damage which in turn leads to reduction in the bearing capacity of the concerned structural members. The aim of this study was to study the effect of partial replacement of fly ash to minimize the corrosion effect. Beams were designed and corroded by using artificial method known accelerated corrosion method. The beams were then tested for flexural and bond strength. Also the weight loss of the reinforced bars was been determined using electrical resistivity method. The fly ash will replace by 10% and 15%.The strength will calculate at varying percentage of corrosion at 10% and 15%. Beams will cast at M25 grade concrete. The flexural strength will test by using UTM and the bond strength will calculate using pullout test.

scholarly journals Properties of Calcium Sulfoaluminate Cement Mortar Modified by Hydroxyethyl Methyl Celluloses with Different Degrees of Substitution

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2136
Author(s):  
Shaokang Zhang ◽  
Ru Wang ◽  
Linglin Xu ◽  
Andreas Hecker ◽  
Horst-Michael Ludwig ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Bond Strength ◽  
Cement Mortar ◽  
Retention Rate ◽  
Methyl Cellulose ◽  
Tensile Bond Strength ◽  
Calcium Sulfoaluminate Cement ◽  
Calcium Sulfoaluminate ◽  
Cement Mortars

This paper studies the influence of hydroxyethyl methyl cellulose (HEMC) on the properties of calcium sulfoaluminate (CSA) cement mortar. In order to explore the applicability of different HEMCs in CSA cement mortars, HEMCs with higher and lower molar substitution (MS)/degree of substitution (DS) and polyacrylamide (PAAm) modification were used. At the same time, two kinds of CSA cements with different contents of ye’elimite were selected. Properties of cement mortar in fresh and hardened states were investigated, including the fluidity, consistency and water-retention rate of fresh mortar and the compressive strength, flexural strength, tensile bond strength and dry shrinkage rate of hardened mortar. The porosity and pore size distribution were also analyzed by mercury intrusion porosimetry (MIP). Results show that HEMCs improve the fresh state properties and tensile bond strength of both types of CSA cement mortars. However, the compressive strength of CSA cement mortars is greatly decreased by the addition of HEMCs, and the flexural strength is decreased slightly. The MIP measurement shows that HEMCs increase the amount of micron-level pores and the porosity. The HEMCs with different MS/DS have different effects on the improvement of tensile bond strength in different CSA cement mortars. PAAm modification can improve the tensile bond strength of HEMC-modified CSA cement mortar.

scholarly journals Analytical Investigation on the Effect of Test Setup on Bond Strength

CivilEng ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 14-34
Author(s):  
Konstantinos Tsiotsias ◽  
Stavroula J. Pantazopoulou
Keyword(s):  
Bond Strength ◽  
Pullout Test ◽  
Analytical Investigation ◽  
Strength Increase ◽  
Confining Stress ◽  
Direct Tension ◽  
Bond Slip ◽  
Test Setup ◽  
Long Time

Experimental procedures used for the study of reinforcement to concrete bond have been hampered for a long time by inconsistencies and large differences in the obtained behavior, such as bond strength and mode of failure, depending on the specimen form and setup used in the test. Bond is controlled by the mechanics of the interface between reinforcement and concrete, and is sensitive to the influences of extraneous factors, several of which underlie, but are not accounted for, in conventional pullout test setups. To understand and illustrate the importance of specimen form and testing arrangement, a series of computational simulations are used in the present work on eight distinct variants of conventional bar pullout test setups that are used routinely in experimental literature for the characterization of bond-slip laws. The resulting bond strength increase generated by unaccounted confining stress fields that arise around the bar because of the boundary conditions of the test setup is used to classify the tests with respect to their relevance with the intended use of the results. Of the pullout setups examined, the direct tension pullout test produced the most conservative bond strength results, completely eliminating the contributions from eccentricity and passive confinement.

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>

scholarly journals Assessment of the mechanical properties of glass ionomer cements for orthodontic cementation

2012 ◽  
Vol 17 (6) ◽  
pp. 154-159 ◽  
Author(s):  
Marcel M. Farret ◽  
Eduardo Martinelli de Lima ◽  
Eduardo Gonçalves Mota ◽  
Hugo Mitsuo S. Oshima ◽  
Gabriela Maguilnik ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Bond Strength ◽  
Shear Bond Strength ◽  
Glass Ionomer Cements ◽  
Glass Ionomer ◽  
Resin Modified Glass Ionomer ◽  
Strength Tests ◽  
Diametral Tensile Strength

OBJECTIVE: To evaluate the mechanical properties of three glass ionomers cements (GICs) used for band cementation in Orthodontics. METHODS: Two conventional glass ionomers (Ketac Cem Easy mix/3M-ESPE and Meron/Voco) and one resin modified glass ionomer (Multi-cure Glass ionomer/3M-Unitek) were selected. For the compressive strength and diametral tensile strength tests, 12 specimens were made of each material. For the microhardness test 15 specimens were made of each material and for the shear bond strength tests 45 bovine permanent incisors were used mounted in a self-cure acrylic resin. Then, band segments with a welded bracket were cemented on the buccal surface of the crowns. For the mechanical tests of compressive and diametral tensile strength and shear bond strength a universal testing machine was used with a crosshead speed of 1,0 mm/min and for the Vickers microhardness analysis tests a Microdurometer was used with 200 g of load during 15 seconds. The results were submitted to statistical analysis through ANOVA complemented by Tukey's test at a significance level of 5%. RESULTS: The results shown that the Multi-Cure Glass Ionomer presented higher diametral tensile strength (p < 0.01) and compressive strength greater than conventional GICs (p = 0.08). Moreover, Ketac Cem showed significant less microhardness (p < 0.01). CONCLUSION: The resin-modified glass ionomer cement showed high mechanical properties, compared to the conventional glass ionomer cements, which had few differences between them.

Analysis of Crack Patterns of 500MPa Reinforced Concrete Beams

2013 ◽  
Vol 790 ◽  
pp. 120-124
Author(s):  
Zhi Hua Li ◽  
Xiao Zu Su
Keyword(s):  
Static Loading ◽  
Crack Width ◽  
Concrete Beams ◽  
Concrete Cover ◽  
Reinforced Concrete Beams ◽  
Crack Control ◽  
Crack Patterns ◽  
Beam Depth ◽  
Steel Bars ◽  
Constant Moment

Fourting concrete beams reinforced with 500MPa longitudinal steel bars, of which 6 with skin reinforcement and 8 without skin reinforcement, were tested under two-point symmetrical concentrated static loading to investigate their crack patterns. Crack distributions in constant moment region of beams are compared. The propagation of side cracks along the beam depth is obtained. The results of this study indicate that the concrete cover of longitudinal tensile steel bars and the spacing of skin reinforcement has significant effect on crack distributions; substantial crack control in beams can be achieved if the spacing of skin reinforcement is limited to certain critical values. The curve of d-w(d is the distance between observation points of side cracks and tension face of beams, w refers to crack width at observation points) is approximately characterized by a zig-zag shape and concave-left near longitudinal tensile steel bars.

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