Influence de la composition du ciment sur l’interface acier galvanisé-béton

Laboratoire Matériaux et Durabilité des Constructions (LMDC) INSA/UPS Génie civil, complexe scientifique de Rangueil, Toulouse

Abstract

The behaviour of galvanized reinforcement, used to prevent corrosion in concrete structures subjected to aggressive conditions, depends on the chemical reaction that occurs between the surface layer of the coating and wet cement paste. In this paper, we study the influence of the chemical composition of the cement on the interface between galvanized reinforcement and concrete. This interfacial zone is characterised by the variation of the surface hardness of the cement paste, X-ray analysis of the compounds, and the bond strength between rebar and concrete. The results indicate that C3A/C3S ratio, alkaline, gypsum and free lime contents in cement are the influencing parameters on the characteristics of this interface. The strength bond of galvanized bar is significantly lower than that of ordinary steel, when it is embedded in concrete made with cement having weak C3A/C3S ratio. Overall, the behaviour of galvanized reinforcement depends on the interaction compounds formed in the interfacial zone and on the evolution of the cement hydration.