scholarly journals An Experimental Study for Quantitative Estimation of Rebar Corrosion in Concrete Using Ground Penetrating Radar

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Md Istiaque Hasan ◽  
Nur Yazdani
Keyword(s):  
Reinforced Concrete ◽  
Quantitative Estimation ◽  
Salt Water ◽  
Water Solution ◽  
Maximum Amplitude ◽  
Accelerated Corrosion ◽  
Oil Emulsion ◽  
Steel Rebar ◽  
Ground Penetrating ◽  
The Relationship

Corrosion of steel rebar in reinforced concrete is one the most important durability issues in the service life of a structure. In this paper, an investigation is conducted to find out the relationship between the amount of reinforced concrete corrosion and GPR maximum positive amplitude. Accelerated corrosion was simulated in the lab by impressing direct current into steel rebar that was submerged in a 5% salt water solution. The amount of corrosion was varied in the rebars with different levels of mass loss ranging from 0% to 45%. The corroded rebars were then placed into three different oil emulsion tanks having different dielectric properties similar to concrete. The maximum amplitudes from the corroded bars were recorded. A linear relationship between the maximum positive amplitudes and the amount of corrosion in terms of percentage loss of area was observed. It was proposed that the relationship between the GPR maximum amplitude and the amount of corrosion can be used as a basis of a NDE technique of quantitative estimation of corrosion.

scholarly journals An experimental study on the shear capacity of corroded reinforced concrete beams without shear reinforcement

2021 ◽  
Vol 15 (1) ◽  
pp. 55-66
Author(s):  
Nguyen Ngoc Tan ◽  
Nguyen Trung Kien
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Concrete Beam ◽  
Reinforced Concrete Beam ◽  
Shear Capacity ◽  
Reinforced Concrete Beams ◽  
Rc Beams ◽  
Accelerated Corrosion ◽  
Steel Rebar ◽  
Accelerated Corrosion Test

The effect of corrosion on the structural behavior of reinforced concrete (RC) beams without stirrups was experimentally investigated. A total of eight medium-scale RC beams were constructed without stirrups. The beams were 150 mm in width, 200 mm in depth, and 1100 mm in length. Test variables included three distinct degrees of corrosion (0%, 3.13%, 4.11%, and 4.93% by mass loss of steel rebar). Six beams were subjected to an accelerated corrosion test, while two beams served as non-corroded control beams. All beams were tested under four-point loading failure after the corrosion stage. The effect of various small degrees of corroded longitudinal reinforcements has been observed for the shear capacity. Test findings found that all tested beams had a brittle failure with tested corrosion degrees. Moreover, corroded beams that are exposed to 3% and 4% average corrosion degree reported having a larger shear capacity of approximately 7% compared to control beams. Lastly, beams with a corrosion degree of about 5% showed a decrease of 10% shear strength and a different failure mechanism with distinguished cracking patterns due to the formation of corrosion cracks along the longitudinal reinforcements. Keywords: reinforced concrete beam; reinforcement corrosion; shear strength; no stirrups.

Effect of mechanical restraint on the rate of corrosion in concrete

1998 ◽  
Vol 25 (1) ◽  
pp. 81-86 ◽  
Author(s):  
N Hearn ◽  
J Aiello
Keyword(s):  
Mix Design ◽  
Concrete Repair ◽  
Accelerated Corrosion ◽  
One Dimensional ◽  
Mechanical Restraint ◽  
Corrosion Rates ◽  
Accelerated Corrosion Tests ◽  
The Matrix ◽  
The Relationship

Experimental work on prismatic concrete specimens was conducted to determine the relationship between mechanical restraint and the rate of corrosion. The current together with the changes in strain of the confining frame were monitored during the accelerated corrosion tests. The effect of mix design and cracking on the corrosion rates was also investigated. The results show that one-dimensional mechanical restraint retards the corrosion process, as indicated by the reduction in the steel loss. Improved quality of the matrix, with and without cracking, reduces the rate of steel loss. In the inferior quality concrete, the effect of cracking on the corrosion rate is minimal.Key words: corrosion, concrete, repair.

scholarly journals Plutonium complexes in water: new approach to ab initio modeling

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Mikhail V. Ryzhkov ◽  
Andrei N. Enyashin ◽  
Bernard Delley
Keyword(s):  
Quantitative Estimation ◽  
Water Solution ◽  
Geometry Optimization ◽  
Model Potential ◽  
Water Dissociation ◽  
New Approach ◽  
Molecular Systems ◽  
Screening Model ◽  
Solvent Environment ◽  
Structure Calculations

Abstract Geometry optimization and the electronic structure calculations of Pu Z+ complexes (Z = 3–6) in water solution have been performed, within the framework of the DMol3 and Relativistic Discrete-Variational (RDV) methods. For the simulation of Pu Z+ molecular environment in aqueous solution we used 22 and 32 water molecules randomly distributed around cation. To model the effect of bulk solvent environment we used COSMO (Conductor-like Screening Model) potential for water (ε = 78.54). The obtained results showed that this approach allows the modeling of water dissociation and the formation of hydrolysis products. Our previously suggested scheme for the calculation of interaction energies between selected fragments of multi-molecular systems provides the quantitative estimation of the interaction strengths between plutonium in various oxidation states and each ligand in the first and second coordination shells in water solution.

Some Characteristics of Irregular Micropulsations Pi2 at High Latitude Stations

1971 ◽  
Vol 49 (18) ◽  
pp. 2338-2349 ◽  
Author(s):  
Jagdish C. Gupta ◽  
Robert J. Stening
Keyword(s):  
High Latitude ◽  
Maximum Amplitude ◽  
Lower Latitude ◽  
Different Types ◽  
Baker Lake ◽  
Hydromagnetic Waves ◽  
Relationship Of ◽  
The Relationship ◽  
Maximum Occurrence

Pi2 micropulsations were studied for the period July 12 to August 16, 1968, from four observatories at different latitudes in Canada. Maximum occurrence was near midnight with a preference for 5–6 h UT at all longitudes studied. The relationship of Pi2 occurrence to magnetic bays and to Kp is examined. The correlation of Pi amplitudes and periods with Kp and other parameters reveals a different pattern for lower latitude stations (Ottawa and Meanook) compared with Baker Lake (73.9 °N). These results are interpreted as evidence for two different types of Pi in the different latitude regions, the lower latitude Pi being associated with hydromagnetic waves on the plasmapause. In studies of simultaneous Pi events at the four stations, the maximum amplitude occurred most frequently at Meanook. Polarization of such events was found to be different at different stations and so previously reported patterns of Pi polarization could not be confirmed.

Laboratory Fast Corrosion Test of Plain Steel Bars in Concrete Beams

2012 ◽  
Vol 535-537 ◽  
pp. 1803-1806
Author(s):  
Shun Bo Zhao ◽  
Peng Bing Hou ◽  
Fu Lai Qu
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Numerical Models ◽  
Concrete Strength ◽  
Reinforced Concrete Beams ◽  
Uniform Corrosion ◽  
Pure Bending ◽  
Accelerated Corrosion ◽  
Steel Bars ◽  
Bending Length

An experimental study was carried out to examine the non-uniform corrosion of plain steel bars in reinforced concrete beams partially placed in 5% sodium chloride solution under conditions of accelerated corrosion. 4 reinforced concrete beams with different concrete strength were made. The crack distributions of the beams due to pre-loads and expansion of corrosion product, and the sectional corrosion characteristics of plain steel bars are described in detail. The sectional area loss relating to mass loss and change along pure bending length of the beams are discussed. These can be used as the basis of test for further studies to build the numerical models of serviceability of corroded reinforced concrete beams.

EEG-correlates of work efficiency level among young persons with stress-induced bruxism

2021 ◽  
pp. 25-29
Author(s):  
A. E. Barulin ◽  
S. V. Klauchek ◽  
A. E. Klauchek
Keyword(s):  
Regression Models ◽  
Alpha Rhythm ◽  
Negative Relationship ◽  
Maximum Amplitude ◽  
Dominant Frequency ◽  
Regression Equations ◽  
Microsoft Excel ◽  
The Subject ◽  
Males And Females ◽  
The Relationship

Purpose of the study. To establish the relationship between neurophysiological status and the level of efficiency in young people with bruxism.Materials and methods. Two groups of 64 and 53 subjects (males and females) aged 20–35 years old with bruxism and non-bruxers were formed according to questionnaire results and physical examination. The level of efficiency was assessed by the results of sensorimotor tracking of a moving object (the ‘Smile’ model). Spectral analysis was performed for evaluation of the baseline electroencephalograms. Microsoft Excel and Statistica 10.0 programs were used for statistical data processing.Results. The level of efficiency was statistically significantly lower in the hardest test of Smile model among the individuals with bruxism (p < 0.05). The bruxers also demonstrated a significantly lower dominant frequency and maximum amplitude of alpha-rhythm (p < 0.05), and significantly higher dominant frequency of beta2 rhythm (p < 0.05). The dominant frequency and the maximum amplitude of the alpha-rhythm are parameters corresponding to significant coefficients of the regression analysis. A negative relationship was found between the degree of error during sensorimotor tracking and the frequency and amplitude of alpha-rhythm.Conclusion. Regression models present the relationship between the level of efficiency and the alpha-rhythm severity. The regression equations make it possible to determine the functional state of the subject using an electroencephalogram.

Shear strength of disturbed regions with corroded stirrups in reinforced concrete beams

2010 ◽  
Vol 37 (8) ◽  
pp. 1045-1056 ◽  
Author(s):  
Christopher Suffern ◽  
Ahmed El-Sayed ◽  
Khaled Soudki
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Concrete Beams ◽  
Corrosion Damage ◽  
Reinforced Concrete Beams ◽  
Test Results ◽  
Accelerated Corrosion ◽  
Damage Level ◽  
Three Point Bending ◽  
Shear Span

This paper reports experimental data on the structural performance of disturbed regions in reinforced concrete beams with corrosion damage to the embedded steel stirrups. A total of 15 reinforced concrete beams were constructed and tested. The test beams were 350 mm deep, 125 mm wide, and 1850 mm long. The beams were tested in three-point bending under a simply supported span of 1500 mm. Nine beams had the embedded stirrups subjected to accelerated corrosion. The test variables were the corrosion damage level and the shear span-to-depth ratio. The test results indicated that the corroded beams exhibited reduced shear strength in comparison to the uncorroded control specimens. The shear strength reduction was up to 53%. Furthermore, the reduction in shear strength due to the corrosion was found to be greater at smaller shear span-to-depth ratios.

Laboratory test of snow wetness influence on electrical conductivity measured with ground penetrating radar

2009 ◽  
Vol 40 (1) ◽  
pp. 33-44 ◽  
Author(s):  
Nils Granlund ◽  
Angela Lundberg ◽  
James Feiccabrino ◽  
David Gustafsson
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Laboratory Test ◽  
Liquid Water ◽  
Ground Penetrating Radar ◽  
Wave Attenuation ◽  
Radar Measurements ◽  
Ground Penetrating ◽  
Radar Wave ◽  
The Relationship

Ground penetrating radar operated from helicopters or snowmobiles is used to determine snow water equivalent (SWE) for annual snowpacks from radar wave two-way travel time. However, presence of liquid water in a snowpack is known to decrease the radar wave velocity, which for a typical snowpack with 5% (by volume) liquid water can lead to an overestimation of SWE by about 20%. It would therefore be beneficial if radar measurements could also be used to determine snow wetness. Our approach is to use radar wave attenuation in the snowpack, which depends on electrical properties of snow (permittivity and conductivity) which in turn depend on snow wetness. The relationship between radar wave attenuation and these electrical properties can be derived theoretically, while the relationship between electrical permittivity and snow wetness follows a known empirical formula, which also includes snow density. Snow wetness can therefore be determined from radar wave attenuation if the relationship between electrical conductivity and snow wetness is also known. In a laboratory test, three sets of measurements were made on initially dry 1 m thick snowpacks. Snow wetness was controlled by stepwise addition of water between radar measurements, and a linear relationship between electrical conductivity and snow wetness was established.

scholarly journals TINGKAT KEASINAN DAN UJI ORGANOLEPTIK TELUR AYAM RAS DENGAN WAKTU PERENDAMAN YANG BERBEDA

2021 ◽  
Vol 4 (1) ◽  
pp. 41-45
Author(s):  
Umbang Arif Rokhayati ◽  
Soegeng Herijanto
Keyword(s):  
Salt Solution ◽  
Salt Water ◽  
Water Solution ◽  
Salinity Level ◽  
Table Salt ◽  
Soaking Time ◽  
Randomized Design ◽  
Salty Taste ◽  
Completely Randomized Design ◽  
Materials Used

The purpose of this study was to determine the organoleptic value of salty taste in eggs soaked in salt solution with different soaking times. The materials used in this study were 90 eggs, rubbing ash and crust salt (table salt). The experimental design used was a completely randomized design (CRD) with 3 treatments and 3 replications. The parameters observed in this study were the organoleptic value and salinity level. The results showed that the duration of soaking eggs in a salt solution had a significant effect on the organoleptic value and salinity of the eggs (P 0.05) on the organoleptic value and the salinity level of the panelists preferred the results of soaking in a salt water solution with a long soaking time of 12 days.

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