The Role of Aluminium in C-A-S-H during Chemical Attack on Concrete

The current trend towards higher proportions supplementary cementitious materials (SCMs) and therefore less clinker in the binder is doubtless environmentally beneficial. Usually, this means an increased aluminium content in the binder compared to pure Portland cement. The properties of the strength-giving C-S-H phases are of primary importance regarding concrete durability. Although the development of crystalline phases and C-S-H during chemical attack has been extensively studied experimentally and with thermodynamic simulations, the role of aluminium in C-A-S-H and, in the presence of potassium, C-K-A-S-H during chemical attack and its effect on concrete durability is still not well understood. In the present work, storage tests with Na2SO4 solutions provide new findings on changes in the nanostructure of C-A-S-H and C-K-A-S-H during sulfate attack. Particular attention is paid to the availability and stability of aluminium and alkalis.      «

The current trend towards higher proportions supplementary cementitious materials (SCMs) and therefore less clinker in the binder is doubtless environmentally beneficial. Usually, this means an increased aluminium content in the binder compared to pure Portland cement. The properties of the strength-giving C-S-H phases are of primary importance regarding concrete durability. Although the development of crystalline phases and C-S-H during chemical attack has been extensively studied experimentall...     »