Talha Doğan Özerdem, M.Sc. Student
Metallurgical and Materials Engineering
Yıldız Technical University
www.linkedin.com/in/talhaozerdem
Development and Characterization of Glass-Ceramic Coated Steel Reinforcements for Increased Strength and Corrosion Resistance in Concrete Structures
Supervisor: Sinan Daloğlu, Assoc Prof. Dr. Buğra Çiçek
Glass-ceramics, filling the gap between inorganic ceramics and glasses, are polycrystalline materials produced through the heat treatment of inorganic glasses. The manufacturing process involves creating glass through standard methods, followed by shaping and slow cooling. Special nucleating agents like TiO2 and ZrO2 are added to induce crystal nuclei formation due to their minimal thermal expansion and partial solubility in melts. Glass-ceramics may be highly crystalline or contain residual glass, composed of glassy and crystalline phases. Controlled nucleation and crystallization occur through sequential thermal processes involving nucleation and crystal growth. This results in the transformation of structurally amorphous glass into a stable solid phase with a regularly ordered geometry[1]. This study aims to investigate the applicability of glass-ceramic coatings to enhance the durability of steel reinforcement bars. Currently, the steel reinforcements of reinforced concrete structures are exposed to atmospheric conditions, leading to corrosion. Therefore, protective coatings are essential to extend the lifespan of reinforcement bars. There are various methods to protect construction steels from corrosion. Some of these are zinc coating, epoxy coating and enamel coating. However, the exact impact of zinc coating on the bond strength between galvanized construction steel and concrete is not fully understood[2]. Hot-dip galvanized zinc coatings have two main concerns in engineering applications. Firstly, if a passive film does not form, the zinc coating undergoes severe corrosion due to the highly alkaline environment in fresh concrete. Secondly, hydrogen produced in cathodic reactions increases the porosity of adjacent cement pastes, thereby reducing the bond strength between bars and concrete[3]. Epoxy coatings may experience adhesion loss and softening over an extended period. The corrosion of damaged epoxy-coated construction iron is higher compared to uncoated construction iron, but broken epoxy coatings can retain moisture, accelerating corrosion[4]. Research studies have indicated that CRE (chemical reactive enamel) coatings can increase corrosion resistance up to 50 times. The effect of calcium and silicate content on the bond strength of CRE-coated construction iron is reported to be seven times higher than regular steel [5]. Additionally, an increase in calcium silicate content enhances surface roughness and the adhesion mechanism, resulting in a 3-4 times increase in bond strength[6].
[1]J. M. Rincon, “Principles of nucleation and controlled crystallization of glasses,” PolymerPlastics Technology and Engineering, vol. 31, no. 3–4, pp. 309–357, 1992,
[2] S.R. Yeomans, Galvanized Steel Reinforcement: Recent Developments and New Opportunities, Proceedings of 5th International Federation for Structural Concrete, Melbourne, Australia, 2018
[3] Tan, Z.Q.; Hansson, C.M. Effect of surface condition on the initial corrosion of galvanized reinforcing steel embedded in concrete. Corros. Sci. 2008, 50, 2512–2522.
[4] J.A. Pincheira, A. Aramayo, D. Fratta, K.S. Kim, Corrosion performance of epoxycoated bars in four bridge decks subjected to deicing salts: 30-year perspective, J. Perform Constr. Fac. 29 (4) (2015)
[5] Microstructural and mechanical characterization of the interface between concrete and chemically reactive enamel (CRE) coated rebar
[6] Effect of chemically reactive enamel coating on bonding strength at steel/mortar interface