engleski

Corrosion of reinforcing steel in alkali activated building materials

Conventional cement-based concrete is a good pair for reinforcing steel. Cement-based concrete carbonates relatively slowly in a low carbon dioxide atmosphere ; well-designed concrete allows only slow diffusion of chlorides and can even physically and chemically bind chlorides. Once the physical and chemical properties of the binder in concrete are changed, a myriad of problems can arise. With alkali-activated materials (AAM) the situation is even more complex as the term alkali- activated materials covers a wide range of precursors and activators, making generalisation virtually impossible. This paper discusses some of the challenges in researching corrosion of reinforcing steel in AAMs. First, some of the methods or coefficients that have been used for decades for conventional concrete need to be adapted for AAMs. Second, the way chlorides and carbon dioxide penetrate through and bind to AAMs can differ significantly from conventional concrete, due to differences in pore structure, tortuosity, and chemistry of reaction products. Finally, the bond and interface between steel and AAM can also be different. Consequently, these differences could lead to changes during the propagation phase of corrosion, and affect the time to cracking and the service life of the structures.

corrosion, alkali-activated materials, half-cell potential, Tafel constants, chloride diffusion

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