Performance of a kinetic model for predicting internal sulphate attack in Portland cement mortars

The present study evaluated an existing kinetic model originally proposed for predicting delayed ettringite formation (DEF) in cementitious systems for potential dual employment to predict internal sulphate attack (ISA). Altogether, 187 data sets taken from the literature were employed to evaluate the model. The data comprised experimental test results of ISA as per ASTM C452, using 25 × 25 × 250 mm mortar prisms prepared at 0.52 to 0.56 water/cement ratios and at the ratio of 1:2.75 cement to fine aggregate. The ISA data were wide-ranging, involving all the various ASTM cement Types I to V. To predict ISA based on depiction of the ASTM C452 test method, 7 % SO 3 and other cement oxides were used as inputs into the model. In contrast, DEF prediction involves using cement composition input without adjustment. It was found that the model gave realistic prediction of ISA in Portland cement systems with reasonable accuracy comparable to performance levels of code-type models. The observed limitations and sources of error are discussed along with suggested future research. Evidently, the kinetic model could potentially be employed to serve the dual purpose of evaluating cement susceptibility to normal ISA or DEF. • ISA – internal sulphate attack, DEF – delayed ettringite formation. • The kinetic model employs actual SO 3 content as input for DEF prediction. • For ISA prediction, the kinetic model employs 7 % SO 3 as constant input. • The kinetic model gives realistic prediction of ISA. • The model correctly depicts ASTM C452 test method with reasonable accuracy.