Crystal chemistry and hydration of Portland cement phases
In this work, various aspects of the alumino and alumino- ferrite phases of cement were studied. The first three chapters wer.e dedicated to the alumino-ferrite phase. The introduction of Ti in the crystal structure of C4AF was the first subject studied. The study was limited to values of Ti substitution which would be realistic with the ones encountered in cements. The early hydration of C4AF and C4AF-Ti solid solution was studied by T.E.M. and reactivity. considerations were made, in conjunction with the defects in the structure, caused by Ti substitution. Finally, the mechanism of gel growth from C4AF crystals was studied by means of the shadow casting technique. The second part of this work was dedicated to the alumino phase of cement. The early mechanism of hydration of C. A and its sodium solid solution in the presence of water andlime water was disclosed, by solution analysis obtained in the region of under-saturation of the system CaO-A2O3-H2O, in respect to the least soluble of the calcium-aluminates (C3AH6). Pore solution of C3A pastes and its Na-containing solid solution were also studied both with and without sulphate. The role of Na in the system was disclosed and the data from pastes was tentatively associated with solution data from other authors.