George Batis

In this work criteria and methodology are proposed for the diagnosis of the durability of steel reinforcement’s in restored monuments. An integrated methodology is applied for the assessment, of traditional buildings from several areas of Greece, such as Rhodes (Kallithea Spa), Chios (Nea Moni Monastery) and Symi (The Bell Tower of St. John Prodromos). Non-destructive techniques were applied in situ

... steel have been evaluated by electrochemical measurements and compared with that obtained from metal loss determination. ... According to the guidelines involved in ASTM C 876, the probability of corrosion initiation is greater than 90 ... Organic corrosion inhibitor effectiveness ...

ABSTRACT The use of coatings (organic and inorganic) for the protection of reinforced concrete is widespread. The advantages of inorganic coatings are that they are stable in UV-radiation, non-combustible, do not foul and have a microcrystalline texture, while organic coatings have the advantage of low permeability of carbon dioxide, sulphur dioxide and water. The aim of the present work was to compare, in the presence of chloride ions, the performance of an acrylic dispersion and a silicate coating, when the latter was or was not combined with a corrosion inhibitor (N-N’-dimethylaminoethanol). The behaviour of the silicate coating was examined as its use is increasing due to environmental reasons and as it can be applied for the rehabilitation of old structures. Half-cell potential measurements, mass loss and carbonation depth measurements, as well as chloride diffusion rate revealed that the acrylic dispersion provides better protection of reinforcing steel in concrete than the silicate coating, but the combination of the silicate coating with the corrosion inhibitor provides the best level of concrete protection.

ABSTRACT The purpose of this work was to investigate the possibilities for the exploitation of the powder by-product of oxygen convertor slag from the ferronickel industry as pigment in anticorrosive non-toxic paints. The chemical composition of the powder shows a large content of Fe3O4 and a high value of pH, two features favouring its use in anticorrosive paints. Paints with this powder, either unrefined or processed, as a pigment and chlorinated rubber resin were produced and tested by the following methods: half-cell potential, mass loss, chloride diffusion and EIS. The results indicated that protection of steel was achieved to a satisfactory level, especially with the processed material.

ABSTRACT The objective of this paper is to investigate the possibility of introducing a natural pozzolan named porfiritis, a natural waste product from the gold mines located in N.E. Chalkidiki Greece, as a supplementary cementing material. Blended cement was produced by replacing PC with 20% w/w porfiritis for the evaluation of the pozzolanic cement properties. Reinforced mortar specimens were either partially immersed in 3.5% w/w NaCl solution or exposed to atmospheric conditions, for a period of 6 months. The experimental methods used were: corrosion potential, corrosion rate by the Linear Polarization method, mass loss, carbonation depth and compressive strength. Based on the results of this study, it is concluded that the use of the porfiritic deposit as a blended cement constituent improves the corrosion behaviour of the mortar specimens, while no serious detrimental effect on the mechanical behaviour of the concrete is detected. Keywords: porfiritis, pozzolanic cements, chlorides corrosion, carbonation. 1 Introduction The blended cement industry is a relatively new and rapidly growing field. The literature on blended cements is extensive, as measurements at laboratory and pilot-plant scale have been carried out over a period of about 50 years. Blended cements provide specific technical advantages in comparison with ordinary Portland cement, with regard to durability in various corrosion environments. One of the most common materials classified as cementitious is natural pozzolans, natural material containing silica in a reactive form [1–3].

... X. BALEC, V, MURAT, M, The emanation thermal analysis of kaolinite clay minerals, Thermochimica Acta, 282, 1996, pp 385-397. ... 19. GALLIAS, JL, KARA-ALI, R, BIGAS, JP, The effect of fine mineral admixtures on water requirement of cement pastes, Cement and Concrete ...

The effect of the addition of lignite fly ash, natural Greek pozzolan and blast furnace slag to ordinary portland cement don the carbonation of mortar specimens was studied in a program of long-term exposure to the atmosphere in relation to the evolution of their porous structure. Additions of 4%, 15% and 30% or 50% of the admixtures to the cement

... contained in this final solution was measured by a selective chloride electrode (Russel 194179B) versus a reference electrode (Russel 90-0029). ... Maslehuddin, M., AI-Mana, AJ, Saricimen, H. & Shamim, M., Corrosion of reinforcing steel in concrete containing slag or pozzolans. ...

ABSTRACT The influence of the addition of 15% and 30% fly ash, 15% and 30% of a Greek natural pozzolan and 50% granulated blastfurnace slag to ordinary Portland cement on the corrosion resistance of the reinforcing bars was studied in a program of long-term exposure to seawater. The use of blended cements resulted in a decrease in the corrosion rate, especially after long exposure times. The most effective protection was rendered by the 30% fly ash mix. This performance was related to the chloride content and the chloride binding capacity of the blended cements.

A brief presentation of a laboratory technique with strain gauges (SG) detecting steel rebars corrosion in mortar specimens is given. The comparison of the application results obtained in specimens containing corrosion inhibitors is discussed in this paper. The present technique is based on the phenomena of tension state, in which the mortar mass comes near the rebar area, during the formation of corrosion products. SG embedded in reinforcing mortar specimens during casting monitor the internal stresses. Mortar specimens with admixtures and corrosion inhibitors, immersed in a 3.5 percent wt NaCl solution, were tested under impressed potential. Corrosion measurements through SG were correlated with those obtained from charge resistant transfer and compared with mass loss of the rebars. The test results obtained indicate that the SG technique, directly related to corrosion products, is suitable for the laboratory study of the influence of corrosion inhibitors in steel protection.

The aim of the present work was to compare the performance of two coating systems applied on steel specimens. The first of them demands sandblasting pretreatment of the metal surface while the second one, which does not need it, leads to rust transformation. These systems were examined in three corrosive environments i.e. a geothermal fluid of low enthalpy, a 3.5 wt per cent NaCl solution and a 5wt per cent NaCl in a salt spray cabinet. The anticorrosive capability of the two coating systems was evaluated at predetermined exposure times by mass loss measurements of the steel substrate, by potentiodynamic polarization curves and by the half-cell potential time evolution. Visual examination of the degree of rusting and blistering was also carried out. The results indicate that both coating systems exhibit almost similar protective behavior under the same conditions of pretreatment. In all cases, the corrosion rate increases with the increase of the surface roughness.

ABSTRACT A number of applications selected with variations of factors affecting the corrosion of mortar steel reinforcements are discussed in this paper. Corrosion estimation by means of a strain gauge (SG) technique was used in several cases to confirm the validity of the method. The efficiency of corrosion inhibitors, the protection offered by the addition of minerals, the curing time influence, and the corrosion resistance of various steel types can be estimated by means of the short term SG test technique. Good correlations were found in all cases of application between the corrosion rates computed from SG technique and the mass loss data. Additionally, the method was applied for swelling measurements of mortar specimens caused by the degradation of FRP reinforcements in the corrosive environments.

Concrete surface coatings, either organic or inorganic, have long been used for the protection of reinforced concrete. The aim of the present work was to compare, in the presence of chloride ions, the performance of an acrylic emulsion and an inorganic coating, when the latter is or is not combined with an inorganic corrosion inhibitor. The behaviour of the inorganic