scholarly journals Rebar corrosion in mortars with high limestone filler content

2013 ◽  
Vol 60 (1) ◽  
pp. 3-13 ◽  
Author(s):  
O.R. Batic ◽  
J.D. Sota ◽  
J.L. Fernández ◽  
N. Bellotti ◽  
R. Romagnoli
Keyword(s):  
Tap Water ◽  
Protective Layer ◽  
Corrosion Current ◽  
High Water ◽  
Passive Layer ◽  
Limestone Filler ◽  
Content Type ◽  
Corrosion Rates ◽  
Lime Water ◽  
Rebar Corrosion

PurposeThis research aims to study the influence of limestone filler on rebar corrosion.Design/methodology/approachMortar samples containing 35% calcareous filler and with a rebar inserted in the axis, were cast. Specimens were cured at the open air and during 28 days in lime water. After curing, they were submerged in two electrolytes (tap water and 3% NaCl) and corrosion parameters (corrosion potential and corrosion current) were monitored over time by d.c. techniques. Simultaneously, electrochemical noise measurements were carried out. After corrosion tests, rebars were pulled out by lateral compression, and their surface observed by scanning electron microscopy.FindingsIn general, carbonate additions impaired mortar protective properties, especially in the presence of chloride and changed the nature of the protective layer on rebars. The curing process did not introduce significant differences except for mortars with a high water cement ratio cured in lime water for which the beneficial effects of the simultaneous presence of carbonate and lime in the pore solution could be appreciated. The role of carbonate additions is to provide carbonate anions to passivate rebars. This passivation process caused corrosion rates not to be so high. Carbonate anions also deposited on oxide spots which were rendered passive but this process was not uniform. Certain areas on the rebar underwent intense carbonation while others showed increased corrosion rates.Originality/valueThere are not many corrosion studies about the influence of limestone filler on rebars corrosion. Particularly, this paper deals with mortars containing high percentages of carbonate additions. Results showed that the presence of this type of admixture changes the structure of the passive layer and, sometimes, may increase corrosion rates.

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.

Effect of sodium molybdate and sodium tungstate in concrete rebar corrosion

2019 ◽  
Vol 66 (3) ◽  
pp. 253-263 ◽  
Author(s):  
Altaf Ahmad ◽  
Ranveer Kumar ◽  
Anil Kumar
Keyword(s):  
Sodium Tungstate ◽  
Sodium Molybdate ◽  
Corrosion Current ◽  
Open Circuit ◽  
Simple Method ◽  
Efficient Inhibitor ◽  
Content Type ◽  
Adverse Conditions ◽  
Cent Sodium ◽  
Rebar Corrosion

Purpose This paper aims to identify an inhibitor to protect rebar corrosion in concrete. Design/methodology/approach The authors use the simple method of polarization and calculate the change in open-circuit potential and corrosion current density. Findings Sodium molybdate is an efficient inhibitor compared with sodium tungstate for rebar corrosion in concrete. Research limitations/implications This paper has limitation of 0.0001 M concentration of inhibitors for 400 days of exposure in 3.5 per cent sodium chloride solution. Originality/value The research focused on the concentration of both inhibitors in the range from 0.1 to 0.0001 M, which resulted in greater structural protection from corrosion in adverse conditions, such as coastal areas.

scholarly journals The Impacts of the Geographic Distribution of Manufacturing Plants on Groundwater Withdrawal in China

Water ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1158
Author(s):  
Yanting Zheng ◽  
Huidan Yang ◽  
Jinyuan Huang ◽  
Linjuan Wang ◽  
Aifeng Lv
Keyword(s):  
Manufacturing Industry ◽  
Tap Water ◽  
Demand Management ◽  
Spatial Regression ◽  
High Water ◽  
Groundwater Withdrawal ◽  
Ecological Environment ◽  
Manufacturing Plants ◽  
Water Users ◽  
Water Transmission

The overexploitation of groundwater in China has raised concern, as it has caused a series of environmental and ecological problems. However, far too little attention has been paid to the relationship between groundwater use and the spatial distribution of water users, especially that of manufacturing factories. In this study, a factory scatter index (FSI) was constructed to represent the spatial dispersion degree of manufacturing factories in China. It was found that counties and border areas between neighboring provinces registered the highest FSI increases. Further non-spatial and spatial regression models using 205 provincial-level secondary river basins in China from 2016 showed that the scattered distribution of manufacturing plants played a key role in groundwater withdrawal in China, especially in areas with a fragile ecological environment. The scattered distribution of manufacturing plants raises the cost of tap water transmission, makes monitoring and supervision more difficult, and increases the possibility of surface water pollution, thereby intensifying groundwater withdrawal. A reasonable spatial adjustment of manufacturing industry through planning and management can reduce groundwater withdrawal and realize the protection of groundwater. Our study may provide a basis for water-demand management through spatial adjustment in areas with high water scarcity and a fragile ecological environment.

scholarly journals Efficiency of Organic Corrosion Inhibitors Derived from Thai-Bael Fruit Extract for Preventing Corrosion in Carbon Steels

2020 ◽  
Vol 32 (8) ◽  
pp. 2043-2050
Author(s):  
Phattarasuda Manantapong ◽  
Nattanon Chaipunya ◽  
Suttipong Wannapaiboon ◽  
Prae Chirawatkul ◽  
Worawat Wattanathana ◽  
...  
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Steel Surface ◽  
Electrochemical Impedance ◽  
Protective Layer ◽  
Corrosion Current ◽  
Carbon Steels ◽  
Fruit Extract ◽  
Polarization Measurements ◽  
Hcl Solution

The inhibiting action of Thai-bael fruit extract at room temperature on hot-rolled steel in 1M HCl solution was studied. The chemical functional groups of the green inhibitors were characterized by Fourier-transformed infrared spectroscopy. The electrochemical activities of steel surface were investigated through linear polarization measurements, electrochemical impedance spectroscopy, surface assessment techniques based on optical microscopy and X-ray absorption spectroscopy. Electrochemical testing samples have been prepared in the form of square plates with the size 1 × 1 cm2. The organic corrosion inhibitor extract from Thai-bael fruit has shown the smallest corrosion current density (Icorr) of 114.8 μA cm-2 and corrosion potential (Ecorr) of -424.6 mV, compared with standard Ag/AgCl electrode potential. In comparison, similar tests in the bare HCl solutions yielded Icorr = 882.4 mA cm-2 and Ecorr = -445.8 mV. The mixed-type corrosion inhibiting behaviour was evidenced in the results of the polarization measurements. Electrochemical impedance spectroscopy reveals that the resistance to charge transfer due to the presence of the extracts has been increased by about four times that of the same test on the bare HCl solution, indicating the formation of a protective layer. The adsorption of the organic molecules near the steel-electrolyte interface is evident in the decreasing double-layer capacitance with the enhancing concentration levels of the extract. This latter finding supports the displacement of the water molecules by means of the adsorption of the inhibitors on the steel surface. The optical images of steel surface before and after being immersed in HCl solution also showed pieces of evidence of corrosion retardation. XANES study as well as the linear combination fitting revealed that the samples immersed in HCl solutions with Thai-bael fruit extract possess less Fe3+ compositions. All tendencies across the four examinations indicate that Thai-bael fruit extract could potentially inhibit the corrosion reaction of steel electrodes in the acidic solution.

scholarly journals Environmental Spread of New Delhi Metallo-β-Lactamase-1-Producing Multidrug-Resistant Bacteria in Dhaka, Bangladesh

2017 ◽  
Vol 83 (15) ◽  
Author(s):  
Mohammad Aminul Islam ◽  
Moydul Islam ◽  
Rashedul Hasan ◽  
M. Iqbal Hossain ◽  
Ashikun Nabi ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Resistance Genes ◽  
Tap Water ◽  
Antibiotic Resistance Genes ◽  
Multidrug Resistant ◽  
Resistant Bacteria ◽  
New Delhi ◽  
Multidrug Resistant Bacteria ◽  
Content Type ◽  
Wastewater Samples

ABSTRACT Resistance to carbapenem antibiotics through the production of New Delhi metallo-β-lactamase-1 (NDM-1) constitutes an emerging challenge in the treatment of bacterial infections. To monitor the possible source of the spread of these organisms in Dhaka, Bangladesh, we conducted a comparative analysis of wastewater samples from hospital-adjacent areas (HAR) and from community areas (COM), as well as public tap water samples, for the occurrence and characteristics of NDM-1-producing bacteria. Of 72 HAR samples tested, 51 (71%) samples were positive for NDM-1-producing bacteria, as evidenced by phenotypic tests and the presence of the bla NDM-1 gene, compared to 5 of 41 (12.1%) samples from COM samples (P < 0.001). All tap water samples were negative for NDM-1-producing bacteria. Klebsiella pneumoniae (44%) was the predominant bacterial species among bla NDM-1-positive isolates, followed by Escherichia coli (29%), Acinetobacter spp. (15%), and Enterobacter spp. (9%). These bacteria were also positive for one or more other antibiotic resistance genes, including bla CTX-M-1 (80%), bla CTX-M-15 (63%), bla TEM (76%), bla SHV (33%), bla CMY-2 (16%), bla OXA-48-like (2%), bla OXA-1 (53%), and bla OXA-47-like (60%) genes. Around 40% of the isolates contained a qnr gene, while 50% had 16S rRNA methylase genes. The majority of isolates hosted multiple plasmids, and plasmids of 30 to 50 MDa carrying bla NDM-1 were self-transmissible. Our results highlight a number of issues related to the characteristics and source of spread of multidrug-resistant bacteria as a potential public health threat. In view of the existing practice of discharging untreated liquid waste into the environment, hospitals in Dhaka city contribute to the potential dissemination of NDM-1-producing bacteria into the community. IMPORTANCE Infections caused by carbapenemase-producing Enterobacteriaceae are extremely difficult to manage due to their marked resistance to a wide range of antibiotics. NDM-1 is the most recently described carbapenemase, and the bla NDM-1 gene, which encodes NDM-1, is located on self-transmissible plasmids that also carry a considerable number of other antibiotic resistance genes. The present study shows a high prevalence of NDM-1-producing organisms in the wastewater samples from hospital-adjacent areas as a potential source for the spread of these organisms to community areas in Dhaka, Bangladesh. The study also examines the characteristics of the isolates and their potential to horizontally transmit the resistance determinants. The significance of our research is in identifying the mode of spread of multiple-antibiotic-resistant organisms, which will allow the development of containment measures, leading to broader impacts in reducing their spread to the community.

Effect of using magnetic water on the mechanical properties of concrete exposed to elevated temperature

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Wasim Barham ◽  
Ammar AL-Maabreh ◽  
Omar Latayfeh
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Elevated Temperature ◽  
Flexural Strength ◽  
Tap Water ◽  
Splitting Tensile Strength ◽  
Content Type ◽  
Normal Water ◽  
Magnetic Water

PurposeThe influence of using magnetic water instead of tap water in the mechanical properties of the concrete exposed to elevated temperatures was investigated. Two concrete mixes were used and cast with the same ingredients. Tap water was used in the first mix and magnetic water was used in the second mix. A total of 48 specimens were cast and divided as follows: 16 cylinders for the concrete compressive strength test (8 samples for each mix), 16 cylinders for the splitting tensile strength (8 specimens for each mix) and 16 beams to test the influences of magnetized water on the flexural strength of concrete (8 specimens for each mixture). Specimens were exposed to temperatures of (25 °C, 200 °C, 400 °C and 600 °C). The experimental results showed that magnetic water highly affected the mechanical properties of concrete. Specimens cast and curried out with magnetic water show higher compressive strength, splitting tensile strength and flexural strength compared to normal water specimens at all temperatures. The relative strength range between the two types of water used was 110–123% for compressive strength and 110–133% for splitting strength. For the center point loading test, the relative flexural strength range was 118–140%. The use of magnetic water in mixing concrete contribute to a more complete hydration process.Design/methodology/approachExperimental study was carried out on two concrete mixes to investigate the effect of magnetic water. Mix#1 used normal water as the mixing water, and Mix#2 used magnetic water instead of normal water. After 28 days, all the samples were taken out of the tank and left to dry for seven days, then they were divided into different groups. Each group was exposed to a different temperature where it was placed in a large oven for two hours. Three different tests were carried out on the samples, these tests were concrete compressive strength, flexural strength and splitting tensile strength.FindingsExposure of concrete to high temperatures had a significant influence on concrete mechanical properties. Specimens prepared using magnetic water showed higher compressive strength at all temperature levels. The use of magnetic water in casting and curing concrete can increase the compressive strength by 23%. Specimens prepared using magnetic water show higher splitting tensile strength at all temperatures up to 33%. The use of magnetic water in casting and curing can strengthen and increase concrete resistance to high temperatures, a significant enhancement in flexural strength at all temperatures was found with a value up to 40%.Originality/valuePrevious research proved the advantages of using magnetic water for improving the mechanical properties of concrete under normal conditions. The potential of using magnetic water in the concrete industry in the future requires conducting extensive research to study the behavior of magnetized concrete under severe conditions to which concrete structures may be subjected to. These days, there are attempts to obtain stronger concrete with high resistance to harsh environmental conditions without adding new costly ingredients to its main mixture. No research has been carried out to investigate the effect of magnetic water on the mechanical properties of concrete exposed to elevated temperature. The main objective of this study is to evaluate the effect of using magnetic water on the mechanical properties of hardened concrete subjected to elevated temperature.

Hydrogen failure sensitivity of A516-Gr70 and API 5L-X70 steels in sour environments

2015 ◽  
Vol 62 (5) ◽  
pp. 294-300 ◽  
Author(s):  
H Taheri ◽  
A Dolati ◽  
Behrooz Beidokhti
Keyword(s):  
Oil And Gas ◽  
Corrosion Current ◽  
Technical Committee ◽  
Committee Report ◽  
Three Solutions ◽  
Content Type ◽  
Hydrogen Induced Cracking ◽  
Two Temperatures ◽  
Current Densities ◽  
Api 5L X70 Steel

Purpose – This paper aims to clarify the corrosion behavior of two famous structural steels in sour environment. These steels have a vast application in oil and gas industries. The study aims to find the effect of different concentrations of sour solution on the origin of crack in these steels. Design/methodology/approach – After preparation of specimens, different sour solutions were made using the synthetic brine (according to National Association of Corrosion Engineers [NACE], Technical Committee Report 1D182) and various amounts of Na2S.9H2O and CH3COOH. The polarization test was done by Potansiostat apparatus model Zahner-IM6 at two temperatures, 25°C and 50°C. The corrosion current densities were obtained from the polarization curves. Finally, the corrosion products and hydrogen-induced cracking (HIC) were investigated by Tescan Vega II XMU scanning electron microscope (SEM) linked to a Rontec energy-dispersive X-ray spectroscopy (EDS) system. Findings – API 5L-X70 steel showed smaller corrosion current values than A516-Gr70 steel. The HIC cracks propagated parallel to the surface of A516-Gr70 steel in three solutions and confirmed the inappropriateness of this steel for sour environment applications. Originality/value – This paper studies the effect of sour environment on the behavior of two famous industrial steels at two temperatures by new method.

The impact of investment on drinking water quality in rural China

2017 ◽  
Vol 9 (2) ◽  
pp. 255-269
Author(s):  
Ai Yue ◽  
Yaojiang Shi ◽  
Renfu Luo ◽  
Linxiu Zhang ◽  
Natalie Johnson ◽  
...  
Keyword(s):  
Water Quality ◽  
Drinking Water ◽  
Rural Areas ◽  
Tap Water ◽  
Rural China ◽  
Ordinary Least Squares ◽  
Content Type ◽  
Representative Data ◽  
Nationally Representative ◽  
The Impact

Purpose Although access to safe drinking water is one of the most important health-related infrastructure programs in the world, drinking water remains a large problem in China today, especially in rural areas. Despite increased government investment in water resource protection and management, there is still an absence of academic studies that are able to document what path the investment has taken and whether it has had any tangible impact. The purpose of this paper is to analyze the impact of drinking water investment on drinking water in China. Design/methodology/approach The authors make use of nationally representative data from 2005 and 2012 to measure the impact of drinking water investment among 2,028 rural households in 101 villages across five provinces. Both ordinary least squares regression and probit regression are used to analyze the correlates and the impact of drinking water investment. Findings The authors demonstrate that water quality was likely a significant problem in 2004 but that China’s investment into drinking water appears to have resulted in initial improvements during the study period. The authors show that the most significant change came about in terms of hardware: villages that received more drinking water investment now have more piped tap water and more access to water treatment infrastructure (disinfecting and filtering facilities). High rates of rural resident satisfaction with drinking water suggest the effects of drinking water investment are being felt at the village level. Originality/value To the authors’ knowledge, this is the first empirical study on drinking water investment over time in rural China using nationally representative data.

scholarly journals Study on Waterproof and Air Permeability of Inorganic Insulated Decorative Panel

2018 ◽  
Vol 175 ◽  
pp. 01001
Author(s):  
Hu Xiang-lei ◽  
Wang Hong-jun ◽  
Gao Ying
Keyword(s):  
Water Vapor ◽  
Weak Link ◽  
Protective Layer ◽  
Outer Wall ◽  
High Water ◽  
Air Permeability ◽  
Composite Panel ◽  
Vapor Flux ◽  
System Supplier ◽  
Complete Set

According to the climatic characteristics, the paper investigates relation between waterproof and air permeability of inorganic insulated decorative panel. The paper believes there are two main problems in the waterproof of inorganic insulated decorative panel, one is the gap is a weak link for waterproof as some weather proofing silicone sealants have poor elastic modulus, the other is the failure of construction details causes partial waterproofing failure. The composite panel system is best supplied in a complete set by the system supplier, which is a main comprehensive solution to the waterproofing problem of the composite panel. Through analyzing software simulation and experimental construction, the paper puts forward suggestion that hot summer and cold winter areas should take practical technical measures, including the use of the protective layer with high water vapor flux density or the installation of exhaust plugs in the outer wall base, or setting water vapor escaping channel such as PVC exhaust plug in the glue seam, in the actual project.

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.

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