Investigation of Organic Coatings Durability on Concrete Reinforcement Corrosion Protection with the Synergistic Influence of Corrosion Inhibitors S.Kalogeropoulou1, P.Pantazopoulou1, Th.Zafeiropoulou2, K. Sideris3 1. Electrical Engineering Department, Technological Educational Institute of Piraeus, Athens, Greece 2. Faculty of Chemical Engineering, National Technical University of Athens, Greece 3. Democritus University of Thrace, Dept. of Civil Engineering, Xanthi, Greece eRA – 9, T.E.I. of Piraeus, 22-24 September 2014

In this work the results obtained until now in the framework of an ARCHIMEDES III research project entitled "Investigation of Organic Coatings Durability on Concrete Reinforcement Corrosion Protection with the Synergistic Influence of Corrosion Inhibitors” are presented. 22/9/2014 eRA-9

Aim of the study The action of various organic coatings and corrosion inhibitors in the protection of steel reinforcement in highly corrosive conditions is investigated. Five different types of organic protective coatings have been chosen to be studied: a two-pack epoxy paint, a two-pack polyurethane paint, a nanotechnology paint and two acrylic dispersions. A classification of the protective action of the organic coatings against corrosion, based on the results of various experimental methods, is presented. 22/9/2014 eRA-9

Reinforcement corrosion – Protection methods Reinforcement corrosion: main cause of reduction of a structure’s life coatings on the surface of concrete corrosion inhibitors cathodic protection stainless steel reinforcement coating of reinforcement available protection methods 22/9/2014 eRA-9

Organic coatings Surface coatings on concrete: prevent the deterioration by creating a physical barrier between the concrete structure and the harmful substances from the environment improve or maintain the appearance offer an effective and reliable solution for the protection both of the concrete and the embedded steel 22/9/2014 eRA-9

Desired properties of organic coatings Good adhesion to concrete even when wet Resistance to high alkalinity of concrete Ability to penetrate into the pores and cracks of concrete Good resistance to ultraviolet (UV) radiation and weathering Good mechanical strength Prevent entry of water but allow water vapor permeation High resistance to the permeation of sulfur dioxide and carbon dioxide and to the penetration of chloride ions in the pores and cracks (less than 0,3 mm) of the concrete 22/9/2014 eRA-9

Alkanolamine-based corrosion inhibitors Corrosion inhibitors have been successfully used as admixtures to concrete to reduce the risk of reinforcement corrosion. Alkanolamine-based corrosion inhibitors move through the pore structure of concrete to reach the surface of reinforcing steel, where they form a protective film reduce chloride ion ingress into concrete are classified as mixed inhibitors, because they influence both the cathodic and the anodic process of corrosion 22/9/2014 eRA-9

Degradation of coatings Μain factors influencing the durability of coatings: sunlight (ultraviolet radiation) moisture heat Τhe result of the combination of these factors is much more serious than each factor individually. Degradation can vary from mere surface discoloration affecting the aesthetic appeal of a product to substantial loss of mechanical properties. 22/9/2014 eRA-9

Properties studied and methods used Reinforcement’s corrosion behavior Effect of UV-radiation to coatings Liquid water and water vapor transmission rates Carbonation depth 22/9/2014 eRA-9

Reinforcement’s corrosion behavior Use of the Strain Gauge (SG) technique, which is based on the appearance of swelling strain near the steel reinforcement in the concrete and is measured by embedded SG sensors in mortar specimens. The cause of the swelling tension is the formation of corrosion products (iron oxides, Fe3O4, Fe2O3, FeO(OH)) having greater specific volume than iron. Determination of the gravimetric mass loss of reinforcing steel bars after a certain period of exposure in the corrosive environment. Mass loss (according to ISO/DIS 8407) is estimated as the difference between the initial and the final mass of the bars, as determined by removing the corrosion products from the bars. 22/9/2014 eRA-9

Effect of UltraViolet-radiation to coatings Dry Film Thickness was measured according to ASTM D4138 “Standard Practices for Measurement of Dry Film Thickness of Protective Coating Systems by Destructive, Cross-Sectioning Means”. Cross cut test was performed according to ISO 2409:1992(E) “Paints and varnishes – Cross cut test” and ASTM D3330 / D3330M - 04(2010) “Standard Test Method for Peel Adhesion of Pressure-Sensitive Tape”. In coated specimens coatings’ adhesion was measured according to BS EN 24624:1993/ BS EN ISO 4624:2003 “Paints and varnishes - Pull off test for adhesion” and ASTM D4541 - 09e1 “Standard Test Method for Pull-Off Strength of Coatings Using Portable Adhesion Testers”. 22/9/2014 eRA-9

Liquid water and water vapor transmission rates Liquid water transmission rate of each coating is determined according to standard DIN EN 1062-3:2008-04 “Paints and varnishes - Coating materials and coating systems for exterior masonry and concrete - Part 3: Determination of liquid water permeability”. Water vapor transmission rate is determined according to standard DIN EN ISO 7783-2 “Coating materials and coating systems for exterior masonry and concrete - Part 2: Determination and classification of water-vapor transmission rate (permeability)”. 22/9/2014 eRA-9

Carbonation depth Measurements of carbonation depth are performed according to BS EN 13295:2004 "Products and systems for the protection and repair of concrete structures - Test methods - Determination of resistance to carbonation" and BS EN 14630:2006 "Products and systems for the protection and repair of concrete structures - Test methods - Determination of carbonation depth in hardened concrete by the phenolphthalein method". 22/9/2014 eRA-9

Materials 1 : 3 : 0.5 Coatings Inhibitor standard proportions cement : sand : water Cement CEM ΙΙ 32.5 Quarry sand Coatings 1 : 3 : 0.5 Water Inhibitor Reinforcement B500C eRA-9

Chemical composition of Portland cement (%wt) SiO2 Al2O3 Fe2O3 CaO MgO K2O Na2O SO3 CaO(f) LOI CEM II 32.5 20.67 4.99 3.18 63.60 2.73 0.37 0.29 2.41 2.52 Chemical composition of steel (%wt) C Mn S P Si Ni Cr Cu V Mo 0.22 1.24 0.044 0.032 0.28 0.09 0.10 0.52 0.075 0.028 22/9/2014 eRA-9

Organic Coatings Categories Two-pack epoxy coating (E) Two-pack polyurethane coating (P) Nanotechnology coating (N) Acrylic emulsion (A) Elastomeric acrylic dispersion (R) Uncoated specimens were used as reference (O) 22/9/2014 eRA-9

Coating procedure The coating procedure for all coatings involves three layers: The appropriate for each coating primer is applied on the dried surface of the specimen, to achieve the best adhesion between coating and mortar. 24 hours The first layer of the organic coating is applied by brush. The second layer of the organic coating is applied by brush perpendicularly to the first one. Coated mortar specimens are stored in the laboratory for at least 7 days, so as coatings are dried and all quantity of solvents has evaporated. 22/9/2014 eRA-9

Organic coatings - technical characteristics S/N Code Product Color Characteristics 1 Ε Epoxy Grey Two-pack epoxy paint with amine hardener, density 1,55 kg/Lt, spreading rate 6 m²/kg (100 μm), solids 95% w/v. 2 P Polyurethane Two-pack polyurethane with aliphatic isocyanic hardener, density 1,20-1,40 kg/Lt, spreading rate 9-11 m²/ Lt (50μm). 3 N Paint for exterior use White Siloxane paint, density 1,60 kg/Lt, solids 50% w/v, spreading rate 8,6 m²/Lt. 4 A Acrylic emulsion paint for exterior use Acrylic dispersion, density 1.46±0.05 g/ml, solids 61±2.5% w/w, pH 8.4±1, spreading rate 9±1 m²/Lt (2 coats). 5 R Elastomeric insulating acrylic paint Acrylic dispersion, undiluted for final coat, density 1.35 g/ml, solids 60±2% w/w, spreading rate 2±1 m²/Lt. 22/9/2014 eRA-9

Primers – technical characteristics S/N Code Product Color Characteristics 1 ΕΑ Epoxy primer (coatings 1-2) Colorless Two-pack epoxy primer, Α:Β-2:1 w/v with hardener, solids 58% w/v, density 0,99 kg/Lt, spreading rate 10 m²/Lt. 2 ΑΑ Acrylic water-based primer (coating 3) Density 1kg/Lt, solids 25,9% w/v, dilution up to 1:4 with water, spreading rate 8-32 m²/Lt. 3 SΑ Styrene-acrylic primer (coatings 4-5) Copolymers of styrene and acrylic resins, density 0.85 g/ml, solids 26±2% w/w, spreading rate 7.5-8.5 m²/Lt. 22/9/2014 eRA-9

Conclusions A: Corrosion evaluation The protective action of all organic coatings against corrosion of the embedded reinforcement is confirmed. Epoxy and polyurethane coatings present an exceptional performance. The nanotechnology coating presents reduced protective ability in accelerated corrosion conditions. For the system “corrosion inhibitor – organic coating” the results have shown that their action is not added. However there is an improvement of the protection given by the coatings with the inhibitor presence, especially in the case of the less effective coatings. 22/9/2014 eRA-9

Conclusions B: UV radiation & Water/Water vapor permeabilities Polyurethane coatings present excellent resistance to ultra violet radiation as compared to epoxy coatings that suffer from yellowing. Both coatings present very low water vapor transmission rate and liquid water permeability. Radiation causes mild degradation to the acrylic and elastomeric emulsions. Both coatings present fairly good behavior towards moisture. The nanotechnology coating resists very well to radiation and presents an improved behavior compared to all other coatings systems regarding water vapor transmission rate and liquid water permeability. 22/9/2014 eRA-9

Conclusions C: Carbonation The two-component industrial coatings with organic solvent (epoxy and polyurethane coatings) provide the best protection. Aqueous dispersions conventional coatings (elastomeric and acrylic dispersions) offer a satisfying level of protection. The nanotechnology coating provides a low and negligible protection rate. 22/9/2014 eRA-9

Acknowledgements This research has been co-financed by the European Union (European Social Fund – ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program: ARCHIMEDES III. Investing in knowledge society through the European Social Fund. 22/9/2014 eRA-9

Thank you for your attention! 22/9/2014 eRA-9