Are alkali activated slag concretes suitable for reinforced concrete structures in chloride environments

Alkali-activated slag (AAS) is a clinker-free binder with dense calcium silicate hydrate structure, but poor overall pore structure of the paste system. Due to its high alumina content, it has the potential for high chloride binding capacity. A review of literature since 1980’s has indicated that in some cases the chloride diffusion in AAS concrete is lower than the Portland cement (PC) counterparts and is comparable to concretes containing high volumes of supplementary cementitious materials, but this has not been found in all cases. Further, less is known about the effect of mix proportions, including binder content, water-binder ratio, both the type and duration of curing, role of activator, etc. on the rate of transport of chloride ions into AAS concretes. In addition, there is conflicting information on the ability of AAS concretes to delay both the onset and the rate of corrosion of embedded steel reinforcement. This paper presents findings from a number of experimental investigations into AAS concretes, especially focusing on the permeation properties and the corrosion behaviour, with an aim to answer whether AAS concretes are suitable where reinforced concrete structures are exposed to chloride environments.