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Search Results: 1 - 10 of 11267 matches for " George Batis "
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Carbonation Resistance and Anticorrosive Properties of Organic Coatings for Concrete Structures  [PDF]
Theodosia Zafeiropoulou, Eleni Rakanta, George Batis
Journal of Surface Engineered Materials and Advanced Technology (JSEMAT) , 2013, DOI: 10.4236/jsemat.2013.31A010

The present study examines the behavior of three major categories of organic coatings which are applied on the surface of concrete structures and specifically conventional, high performance and nanotechnology paint systems. The comparison is achieved in the means of anticorrosion properties under the presence of chloride ions and carbonation resistance. The evaluation methods included electrochemical measurements in order to assess corrosion properties and the determination of steel’s mass loss after the end of the experimental procedure. Carbonation depth was measured using phenolphthalein as indicator after accelerated and physical exposure. From the results so far it can be shown nanocoatings gave promising results regarding induced chloride ion corrosion.

Protection Systems for Reinforced Concrete with Corrosion Inhibitors  [PDF]
Angeliki Zacharopoulou, Eugenia Zacharopoulou, George Batis
Open Journal of Metal (OJMetal) , 2014, DOI: 10.4236/ojmetal.2014.44010
Abstract: This paper examines the use of corrosion inhibitors in order to protect the reinforcement of concrete. For this purpose mortar specimens were constructed with or without corrosion inhibitors and were partially immersed in sodium chloride. Corrosion inhibitors were used as admixture into concrete and were sprayed on the external surface of mortar specimens. In all mortar specimens, electric junction between reinforcements was achieved. The methods that were used for the evaluation of the reinforcement corrosion in concrete, included half-cell potential measurements, polarization curves of reinforced rebars and mass loss of the reinforcement. Finally, the durability of concrete after the use of corrosion inhibitors was also examined.
Efficiency of Amino Alcohols as Corrosion Inhibitors in Reinforced Concrete  [PDF]
Ioannis Vyrides, Eleni Rakanta, Theodosia Zafeiropoulou, George Batis
Open Journal of Civil Engineering (OJCE) , 2013, DOI: 10.4236/ojce.2013.32A001

The objective of this paper is to investigate the behaviour of amino alcohol corrosion inhibitors when they are used in reinforced cement mortars either as admixtures in the cement paste or as coating applications on the surface of the rebars. The reinforced cement mortars were exposed to both partial and full immersion in 3.5 wt% NaCl solution. Electrochemical measurements such as half-cell potential and linear polarization technique, as well as weight loss of the embedded rebars were performed in order to obtain information on the corrosion behaviour of the reinforcing steel in cement mortar. Results demonstrate that the amino alcohol corrosion inhibitors offer protection against rebar corrosion in cement mortars.

Effect of Corrosion Inhibitors in Limestone Cement  [PDF]
Evgenia Zacharopoulou, Aggeliki Zacharopoulou, Atteyeh Sayedalhosseini, George Batis, Sotirios Tsivilis
Materials Sciences and Applications (MSA) , 2013, DOI: 10.4236/msa.2013.412A003

In this paper examines the improving durability of different limestone cement and effects of the use of corrosion inhibitor. The target is to experimentally investigate the effect of different types of cement in corrosion of reinforcement in presents of corrosion inhibitors and without it. Three types of cement have been used: CEM II, LC1 and LC2. For this purpose constructed mortar specimens, containing 4 reinforcements, with or without corrosion inhibitors for each group, these exhibited to partial immersion in sodium chloride in 3.5% w.t NaCl solution. The methods, with which the corrosion of reinforcement in concrete was tested, were measurements of corrosion potential, corrosion current and mass loss of reinforcement. The mortars with CEM II cement have better durability than that with limestone cement. The use of VpCI, Cyclohexylammonium benzoate, improves the corrosion protection of mortars with CEM II cement upper 50%. On the other hand, the addition of VpCI, Cyclohexylammonium benzoate, improves the corrosion protection of mortars with limestone cement 30% or lower.

Effect of Organic Coating Corrosion Inhibitor on Protection of Reinforced Mortar  [PDF]
Evgenia Voulgari, Aggeliki Zacharopoulou, Nikolaos Chousidis, George Batis
Journal of Materials Science and Chemical Engineering (MSCE) , 2019, DOI: 10.4236/msce.2019.71003
Abstract: Corrosion of reinforced concrete is the most important cause of concrete structure deterioration. In the present study, the protective effect of the reinforcement mortars against corrosion is examined. In particular, the chloride penetration resistance on reinforced cement mortars using organic coating as additive containing was studied. The aforementioned additive consists of corrosion inhibitor for protection of steel rebars against pitting corrosion. For the experimental procedure, four (4) different types of reinforced mortars were prepared. The corrosion protection of the additive was evaluated by electrochemical methods, (linear polarization resistance, Half-cell Potential Resistance and Electrochemical Impedance Spectroscopy). In addition, the mass loss of steel rebars against time of partially immersed in NaCl solution was carried out in the lab. The experimental results showed that in all examined cases the organic coating provides anticorrosion protection on steel rebars against chlorides.
Anticorrosive Effect of Electrochemical Manganese Dioxide By-Products in Reinforced Concrete  [PDF]
N. Chousidis, E. Rakanta, I. Ioannou, G. Batis
Journal of Materials Science and Chemical Engineering (MSCE) , 2015, DOI: 10.4236/msce.2015.35002
Abstract: The present study investigates the effect of Electrochemical Manganese Dioxide (EMD) by-product as a replacement of cement, on durability of concrete and the corrosion protection of reinforcement steel. Reinforced cement mortars were partially immersed in 3.5% w. w NaCl solution and they were exposed to atmospheric conditions for a period of 24 months. Additions of 5% and 10% EMD byproduct were tested. The following techniques were used: half-cell potential measurements (HCP), linear polarization Resistance (LPR), mass loss of reinforcement steel, determination of carbonation depth of mortars, testing of compressive strength, total and open porosity measurements. Based on the up-to-now results of this study, the specimens with addition 10% appear smaller corrosion currents and mass loss of steel than reference specimens. Also, the compressive strength with 10% additive is appeared to be slightly higher from the reference specimens.
Statistics Analysis Measures Painting of Cooling Tower
A. Zacharopoulou,E. Zacharopoulou,G. Batis
International Journal of Corrosion , 2013, DOI: 10.1155/2013/389159
Abstract: This study refers to the cooling tower of Megalopolis (construction 1975) and protection from corrosive environment. The maintenance of the cooling tower took place in 2008. The cooling tower was badly damaged from corrosion of reinforcement. The parabolic cooling towers (factory of electrical power) are a typical example of construction, which has a special aggressive environment. The protection of cooling towers is usually achieved through organic coatings. Because of the different environmental impacts on the internal and external side of the cooling tower, a different system of paint application is required. The present study refers to the damages caused by corrosion process. The corrosive environments, the application of this painting, the quality control process, the measures and statistics analysis, and the results were discussed in this study. In the process of quality control the following measurements were taken into consideration: (1) examination of the adhesion with the cross-cut test, (2) examination of the film thickness, and (3) controlling of the pull-off resistance for concrete substrates and paintings. Finally, this study refers to the correlations of measurements, analysis of failures in relation to the quality of repair, and rehabilitation of the cooling tower. Also this study made a first attempt to apply the specific corrosion inhibitors in such a large structure. 1. Introduction Generally the concrete comprises a protective environment of the reinforcement for the two reasons following.(i)The aqueous solution of the pores of the reinforcement is intensely alkaline due to lime, which is the product of reaction of the cement hardening, its pH between 12.5 and 13.9. Under these circumstances, steel is superficially covered by a passive layer of iron oxides, which impedes its corrosion. Steel corrosion is restrictive to the maintenance of this passive layer; an action is so slow that it could practically be ignored.(ii)The concrete acts as a natural barrier between the reinforcement and the various corrosive elements of the environment (such as oxygen and carbon dioxide) as well as other substances which may induce corrosion (such as chlorides). In time, cement may lose its protective capacity, for example, due to carbonation which is the reaction of carbon dioxide with calcium hydroxide. Then the pH may reach scales lower than 9, so the steel passes from the passive into the active state. Another reason for the corrosion of the reinforcement is the existence of chlorides. Chlorides penetrate the passive layer of oxides and cause
Experimental Investigation of Bed Joint Reinforcement Corrosion in Masonry Mortars  [PDF]
Alexandros Stathatos, Angeliki Zacharopoulou, Georgios Batis, Elisavet Vintzileou
Open Journal of Metal (OJMetal) , 2016, DOI: 10.4236/ojmetal.2016.61001
Abstract: The paper investigates the behaviour against corrosion offered by seven masonry mortar compositions to the reinforcement placed in masonry bed joints. Durability protection was evaluated on the basis of four criteria: carbonation area of the specimens, mass loss of steel, electrochemical potential and presence of chloride ions. Tests were performed against two corrosive environments, with and without chloride ions, and were carried out for three periods: three, six and thirty three months. Two types of steel were used, plain steel and galvanized steel. Moreover, the steel protective action of a corrosion inhibitor, sodium nitrite, was examined. A qualitative comparison approach against prototype concrete-like mortars was used. The results showed that the selected masonry mortars did not exhibit similar properties against corrosion to those of concrete and that the addition of sodium nitrite decrease of the corrosion rate only 5% - 20% did not meaningfully improve durability properties. Nevertheless, the addition of lime in small quantities did not have a negative impact on the mortars’ durability characteristics, e.g. the same average corrosion rate.
Venture Capital and Innovation in Europe  [PDF]
George Geronikolaou, George Papachristou
Modern Economy (ME) , 2012, DOI: 10.4236/me.2012.34058
Abstract: In this paper we search for evidence signifying whether VC activity is demand or supply stimulated. Namely, we examine whether innovation and entrepreneurship are fostered by Venture Capital (VC) investments or whether innovative entrepreneurship is a precondition of a VC involvement. Based on a European panel of VC investments, we test the direction of causality between VC and innovation (proxied by annual patent applications at the European Patents Office). We present evidence indicating that causality runs from patents to VC suggesting that, in Europe, innovation seems to create a demand for VC and not VC a supply of innovation. In this sense, innovative ideas seem to lack more than funds in Europe. We explain our findings on the basis of information asymmetry issues and irreversibility considerations of VC investments.
The Index of Invariant Subspaces of Bounded below Operators on Banach Spaces  [PDF]
George Chailos
Advances in Pure Mathematics (APM) , 2012, DOI: 10.4236/apm.2012.22018
Abstract: For an operator on a Banach space , let be the collection of all its invariant subspaces. We consider the index function on and we show, amongst others, that if is a bounded below operator and if , , then If in addition are index 1 invariant subspaces of , with nonzero intersection, we show that . Furthermore, using the index function, we provide an example where for some , holds .
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