A study on the passive state stability of steel embedded in activated fly ash mortars

Abstract

The main reason for the premature failure of reinforced concrete structures (RCS) is corrosion of the reinforcements. The use of new mortars based on activated fly ash, an alternative to conventional portland cement, requires extensive research in order to check its passivating properties for reinforcements and the instability or permanence of the passive state achieved. The present paper studies this objective, analysing the passivating capacity of specimens manufactured with three different fly ash mortars treated with three activators and the stability of the passive state under the effect of 0%, 0.2%, 0.4% and 2% chloride additions in relation to the binder material, in an environment of apparently constant humidity and in humidity cycles. The evolution with time of corrosion potential (Ecorr) and polarisation resistance (Rp) was studied. Polarisation curves and time constants (τ) were also assessed for some specimens using short duration galvanostatic pulses.