Abstract
A model is proposed for predicting the intrinsic potential of Portland cements to exhibit delayed ettringite formation, when used in cementitious systems. The model has been developed on the basis of kinetic reaction theory and consists of a set of two equations which define the primary conditional requirements on cement chemistry. The important conditions, sufficient alumina content exceeding a certain unknown threshold and SO3/Al2O3 ratio high enough to promulgate ettringite infilling pressures over and above counter microstructural factors, are mathematically expressed. Both conditions have been reported in the literature by various authors basing on experimental observations.
The proposed model can be a useful screening tool for rapid evaluation of cements against their proneness to delayed ettringite formation (DEF) and may be applied in cement manufacture, import depots, ready-mix plants, and many others or for selection of cements for specific applications. Due to the intrinsic nature of the model, it has the potential to reveal the underlying expansive behaviour that may be suppressed or not easily observed from experimental tests alone. Validation of the model against experimental data from literature has been undertaken in