This study aims to make an effort to develop a model to predict the residual flexural strength of reinforced concrete beams subjected to reinforcement corrosion.
Abstract
Purpose
This study aims to make an effort to develop a model to predict the residual flexural strength of reinforced concrete beams subjected to reinforcement corrosion.
Design/methodology/approach
For generating the required data to develop the model, a set of experimental variables was considered that included corrosion current density, corrosion duration, rebar diameter and thickness of concrete cover. A total of 28 sets of reinforced concrete beams of size 150 × 150 × 1,100 mm were cast, of which 4 sets of un-corroded beams were tested in four-point bend test as control beams and the remaining 24 sets of beams were subjected to accelerated rebar corrosion inducing different levels of corrosion current densities for different durations. Corroded beams were also tested in flexure, and test results of un-corroded and corroded beams were utilized to obtain an empirical model for estimating the residual flexural strength of beams for given corrosion current density, corrosion duration and diameter of the rebars.
Findings
Comparison of the residual flexural strengths measured experimentally for a set of corroded beams, reported in literature, with that predicted using the model proposed in this study indicates that the proposed model has a reasonably good accuracy.
Originality/value
The empirical model obtained under this work can be used as a simple tool to predict residual flexural strength of corroded beams using the input data that include rebar corrosion rate, corrosion duration after initiation and diameter of rebars.
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Shamsad Ahmad and Mohammed M. Hussein Al-Tholaia
The purpose of this paper was mainly to select one of the three types of coatings for protection of steel used as reinforcement in composite pipes (thin steel shell covered by…
Abstract
Purpose
The purpose of this paper was mainly to select one of the three types of coatings for protection of steel used as reinforcement in composite pipes (thin steel shell covered by cement-mortar) subjected to chloride exposure. To achieve this target, an attempt was made to develop a simple methodology for evaluating the performance of corrosion protection measures in terms of chloride threshold level (CTL) and corrosion initiation time (TI).
Design/methodology/approach
Bare, epoxy, red oxide and zinc primer-coated steel strips were embedded in cement mortar with sand/cement and water/cement ratios of 2 and 0.5 (by mass), respectively, to prepare the specimens which were exposed to chloride solution having a high concentration of 10 per cent NaCl. For determining the amounts of the water-soluble chloride diffused inside the specimens, powdered samples of mortar were collected from two different depths from the exposed surface of specimens on completion of each of the four different exposure times. The corrosion current densities were determined at two different stages. A step-by-step procedure for calculating CTL and TI using the measured chloride contents and corrosion current densities was established with the help of relevant information available in the literature.
Findings
Based on the comparison of the values of CTL and TI calculated for bare steel and steel with all three types of coatings, utilizing the experimental data and the proposed calculation procedure, the epoxy-coated steel was found to have the best performance.
Originality/value
This research has resulted into development of a simple methodology for evaluation of the performance of protective measures against corrosion of steel embedded in mortar or concrete exposed to chloride-bearing environment.
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The purpose of this paper was to explore the possibility of establishing an empirical correlation between concrete resistivity and reinforcement corrosion rate utilizing the…
Abstract
Purpose
The purpose of this paper was to explore the possibility of establishing an empirical correlation between concrete resistivity and reinforcement corrosion rate utilizing the experimental data generated by measuring corrosion current density of reinforced concrete specimens subjected to chloride-induced corrosion at different levels of concrete resistivity.
Design/methodology/approach
To generate concrete resistivity vs corrosion current density data in a wide range, ten reinforced concrete specimens were prepared and allowed to corrode under severe chloride exposure. After significantly corroding the specimens, they were removed from the chloride exposure and were subjected to different moisture levels for achieving variation in the resistivity of concrete so that reasonably good number of resistivity vs corrosion rate data can be obtained. Resistivity and corrosion current density tests were conducted for all the ten specimens and their values were measured in wide ranges of 0.8-65 kΩ·cm and 0.08-11 μA/cm2, respectively.
Findings
Data generated through this study were utilized to obtain an empirical relationship between concrete resistivity and corrosion current density. The trend of results obtained using the empirical correlation model developed in the present study was in close agreement with that obtained using a theoretical model reported in literature.
Originality/value
The empirical correlation between concrete resistivity and reinforcement corrosion rate obtained under this work can be used for evaluation of reinforcement corrosion utilizing the resistivity values measured non-destructively.
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Argyro Drakakaki, Alkiviadis Apostolopoulos and Charis Apostolopoulos
The safety of reinforced concrete structures is generally related to the expected service life of their individual materials. Corrosion damage manifesting on steel reinforcement…
Abstract
Purpose
The safety of reinforced concrete structures is generally related to the expected service life of their individual materials. Corrosion damage manifesting on steel reinforcement is usually underestimated, although it greatly affects both load bearing capacity and plastic deformation limits of steel reinforcement. Corrosion damage degree has a great impact on the life expectancy of structures. This paper aims to discuss these issues.
Design/methodology/approach
In the present study, an effort has been made to examine and present critical parameters, which are significantly responsible for the differentiation of the corrosion damage level, as far as mass loss is concerned. Consequently, the size effect of the exposed – to the aggressive conditions – area of the specimen, as well as the volume of the protected (against corrosion) area, was examined in detail.
Findings
Differential aeration greatly affects the results of corrosion on the material, given that under both high and low oxygen concentration corrosion process is still ongoing.
Originality/value
Findings proceeded are worth mentioning, as they may contribute to a more pertinent evaluation of the corrosion damage (as far as mass loss is concerned), restricting the risk of erroneous predictions concerning the mechanical behavior of steel reinforcement.