Prediction of carbonation using reactivity test methods for pozzolanic materials

The influence of the capacity of supplementary cementitious materials (SCMs) to consume portlandite on the carbonation resistance of mortar was investigated. Seven different mineral additives (two types of slag, two types of fly ash, two calcined clays and limestone) were used and their reactivity was measured using isothermal calorimetry, strength index measurements, Chapelle's test and thermogravimetric analysis. Mortar samples were cast by substituting 30% cement by mass with SCMs and their carbonation performance was investigated. The carbonation resistance of cement was found to have no specific correlation with the compressive strength of the mortar cast using it. Different reactivity test methods showed a reasonable correlation between the reactivity of the non-hydraulic SCM and the carbonation resistance of the cement containing that SCM. The performance of different cement binders under carbonation was found to be influenced by the alkaline content and compressive strength collectively.