scholarly journals CORROSION BEHAVIOR OF REINFORCING STEEL IN RC SLAB CONTAINING CHLORIDES WITH PARTIAL REPLACEMENT OF CEMENT AS FLY ASH

2019 ◽  
Vol 31 (3) ◽  
Author(s):  
Sristi Das Gupta ◽  
Takafumi Sugiyama ◽  
Md Shafiqul Islam
Keyword(s):  
Reinforced Concrete ◽  
Fly Ash ◽  
Current Density ◽  
Corrosion Current Density ◽  
Corrosion Current ◽  
Concrete Cover ◽  
Partial Replacement ◽  
Normal Concrete ◽  
Fly Ash Concrete ◽  
Rc Slab

Steel reinforcement in concrete containing fly ash has been practically employed to RC structures in snowy cold region and coastal areas so that the durability of the structures against corrosion can be enhanced. In this research to make the compatibility with RC slab bridge sodium chloride solution of 10[WU1] % in concentration was applied on RC slab and corrosion development was monitored by electrochemical method. Applying fly ash in RC slab at two replacement levels of 15[WU2] % (F15) and 30% (F30) of cement the specimens were observed. The observation result verified that fly ash concrete showed longer period of corrosion initiation (ASTM C876) than normal reinforced concrete. The initiation period of corrosion was 4.5 and 6 times longer for F15 and F30 concrete than normal concrete, as well as 91 days strength of F30 concrete was about 14% higher that of norma concrete. Test result showed that fly ash has better influence on steel corrosion reduction than concrete cover increment. It was observed that fly ash concrete (F15 and F30) with 3 cm concrete cover has better corrosion resistivity than using 4 cm cover of non-fly ash concrete. Furthermore, using the same concrete cover (3 cm) it was found that the actual corrosion rate was decreased about 68 to 82% by adding fly ash 15 to 30% respectively compared to normal reinforced concrete. In addition, a significant attenuation in corrosion area in rebar between fly ash concrete and normal concrete was found. Based on actual corrosion area on rebar surface, actual corrosion current density was larger than corrosion current density found from non-destructive way. Moreover, further analysis was conducted for characterization of different corrosion products using Raman spectroscopy with 532 nm wave length. It revealed that the corrosion product (Oxides and Oxyhydroxides compound) were less in F15 and F30 concrete compared to normal concrete. Considering these results, the possibility of reduction of chloride induced corrosion in reinforced concrete structure using fly ash has confirmed. 

An experimental study on correlation between concrete resistivity and reinforcement corrosion rate

2014 ◽  
Vol 61 (3) ◽  
pp. 158-165 ◽  
Author(s):  
Shamsad Ahmad
Keyword(s):  
Reinforced Concrete ◽  
Corrosion Rate ◽  
Current Density ◽  
Corrosion Current Density ◽  
Corrosion Current ◽  
Empirical Correlation ◽  
Reinforcement Corrosion ◽  
Content Type ◽  
Wide Range ◽  
Concrete Resistivity

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.

Prediction of residual flexural strength of corroded reinforced concrete beams

2017 ◽  
Vol 64 (1) ◽  
pp. 69-74 ◽  
Author(s):  
Shamsad Ahmad
Keyword(s):  
Reinforced Concrete ◽  
Flexural Strength ◽  
Current Density ◽  
Empirical Model ◽  
Corrosion Current Density ◽  
Concrete Beams ◽  
Corrosion Current ◽  
Reinforced Concrete Beams ◽  
Content Type ◽  
Rebar Corrosion

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.

Exploring optimum percentage of fly-ash as a replacement of cement for enhancement of concrete properties

2020 ◽  
Vol 11 (1) ◽  
pp. 16
Author(s):  
Sarvat Gull ◽  
Shoib B. Wani ◽  
Ishfaq Amin
Keyword(s):  
Fly Ash ◽  
Progressive Increase ◽  
Decision Makers ◽  
Partial Replacement ◽  
General Increase ◽  
Normal Concrete ◽  
Fly Ash Concrete ◽  
Optimum Quantity ◽  
Lab Experiments ◽  
Management Scheme

Researchers and decision makers are continuously looking out to determine the potential and effectiveness of fly-ash as a partial replacement of cement in concrete. The current study is carried out to check the optimum or nearly optimum quantity of fly-ash with which cement should be replaced to get most of the properties of concrete enhanced and to give the idea about the quantities of fly-ash that can be used in a better way and better cause so that a proper management scheme of its usage and disposal can be implied. Further, a comparison is given between normal concrete and fly-ash concrete to show the properties which can be enhanced by proper utilization of fly-ash as a partial replacement of cement. After carrying out the lab experiments, it has been seen that the replacement of fly-ash in concrete has resulted in general increase in compressive strength, flexural strength and splitting tensile strength up to 15% replacement and after then the strength is decreased considerably than that of normal concrete. Addition of fly-ash in concrete has resulted in decrease in the water absorption of concrete and hence decreases in permeability of concrete. There is a progressive increase in workability with increase in percentage of fly-ash in concrete. The current study has led to a conclusion that in order to achieve best results in use of fly-ash concrete, the fly-ash used for replacing cement in concrete should have the required properties as specified by the standards and proper techniques of processing fly-ash as well as mixing of fly-ash with cement must be employed.

scholarly journals Temperature Impact on the Assessment of Reinforcement Corrosion Risk in Concrete by Galvanostatic Pulse Method

2020 ◽  
Vol 10 (3) ◽  
pp. 1089 ◽  
Author(s):  
Wioletta Raczkiewicz ◽  
Artur Wójcicki
Keyword(s):  
Current Density ◽  
Corrosion Current Density ◽  
Pulse Method ◽  
Corrosion Current ◽  
Concrete Cover ◽  
Effect Of Temperature ◽  
Reinforcement Corrosion ◽  
Stationary Potential ◽  
Corrosion Risk ◽  
The Impact

The electrochemical galvanostatic pulse method (GPM) is used for the evaluation of the degree of corrosion risk of reinforcement in concrete. This non-destructive method enables determining the corrosion promoting conditions through the measurements of reinforcement stationary potential and concrete cover resistivity, and determining the probability of reinforcement corrosion in the tested areas. This method also allows for the estimation of the reinforcement corrosion activity and the prediction of the development of the corrosion process on the basis of corrosion current density measurements. The ambient temperature (and the temperature of the examined element) can significantly affect the values of the measured parameters due to electrochemical character of the processes as well as specific measurement technique. Differences in the obtained results can lead to a wrong interpretation of reinforcement corrosion risk degree in concrete. The article attempts to assess the effect of temperature on the measured parameters while using the galvanostatic pulse method. The GP-5000 GalvaPulseTM set was used. The results of this study confirmed the impact of temperature changes on the values of three measured parameters (reinforcement stationary potential, concrete cover resistivity, and corrosion current density) and contributed to catching the trend of these changes.

Prediction of Steel Bar Corrosion of RC Members Deteriorated by Pre-Existed Chloride and Concrete Carbonation

2015 ◽  
Vol 723 ◽  
pp. 410-418
Author(s):  
Xin Xue ◽  
Wen Xiong ◽  
Hui Chao Wang ◽  
Cong Zhou Shen
Keyword(s):  
Current Density ◽  
Corrosion Current Density ◽  
Corrosion Current ◽  
Area Ratio ◽  
Concrete Cover ◽  
Total Chloride ◽  
Concrete Carbonation ◽  
Cover Concrete ◽  
Steel Bars ◽  
Combined Action

By simulating solo or combined deterioration action of pre-existed chloride and concrete carbonation, this paper carried out an experimental investigation on the corrosion state of steel bars embedded in concrete with different concrete cover thicknesses and containing different chloride amounts. Comparisons of corrosion current density, corrosion area ratio and corrosion weigh loss of embedded steel bars were made and the effect of combined action was systematically studied. Test results indicated that under the combined action, the corrosion current density measured soon after concrete carbonation test increased with the total chloride amount containing in cover concrete, and the specimens under the combined action exhibited larger value of corrosion current density, corrosion area ratio and mass weight loss than that of the specimens subjected to the solo action. It was further indicated that the mass loss ratio of embedded steel bars at the point of corrosion crack initiation was 1.29% for the specimens with 5mm concrete cover, and the corresponding value of the specimens with 10mm concrete cover was 1.33%.

scholarly journals Prediction of the Corrosion Current Density in Reinforced Concrete Using a Self-Organizing Feature Map

Coatings ◽  
2017 ◽  
Vol 7 (10) ◽  
pp. 160 ◽  
Author(s):  
Mehdi Nikoo ◽  
Łukasz Sadowski ◽  
Mohammad Nikoo
Keyword(s):  
Reinforced Concrete ◽  
Current Density ◽  
Corrosion Current Density ◽  
Corrosion Current ◽  
Feature Map ◽  
Self Organizing

scholarly journals An electrochemical method to investigate the effects of compound composition on gold dissolution in thiosulfate solution

2020 ◽  
Vol 9 (1) ◽  
pp. 496-502 ◽  
Author(s):  
Zhaohui Zhang ◽  
Bailong Liu ◽  
Mei Wu ◽  
Longxin Sun
Keyword(s):  
Dissolution Rate ◽  
Current Density ◽  
Polarization Resistance ◽  
Electrochemical Method ◽  
Corrosion Current Density ◽  
Corrosion Potential ◽  
Corrosion Current ◽  
Gold Dissolution ◽  
Tafel Polarization ◽  
Edta Solution

AbstractThe electrochemical behavior of gold dissolution in the Cu2+–NH3–S2O32−–EDTA solution has been investigated in detail by deriving and analyzing the Tafel polarization curve, as this method is currently widely implemented for the electrode corrosion analysis. The dissolution rate of gold in Cu2+–NH3–S2O32−–EDTA solution was determined based on the Tafel polarization curves, and the effects of various compound compositions in a Cu2+–NH3–S2O32−–EDTA mixture on the corrosion potential and corrosion current density were analyzed. The results showed that the corrosion potential and polarization resistance decreased, whereas the corrosion current density increased for certain concentrations of S2O32−–NH3–Cu2+ and EDTA, indicating that the dissolution rate of gold had changed. The reason for promoting the dissolution of gold is also discussed.

Sign in / Sign up

Export Citation Format

Share Document