Morphological Differentiation and Crystal Growth Form of Friedel’s Salt Originated from Pozzolan and Portland Cement

Abstract

This paper has a scientific−technical character and deals with morphological comparison of Friedel's salt (Fs), which is a compound that is originated from two routes: C3A phase of Portland cement (PC) and Al2O3 r− (reactive alumina) of pozzolans. The reaction courses are contrasted and the role of reactive components is discussed in detail. The results show a great difference in morphology of the Fs, relative to the function of its origin, which is directly related to its very different formation rate: Friedel's salt of rapid formation (Fs-rf) or Friedel's salt of slow formation (Fs-lf). The reactive alumina (Al2O3 r− ) component of pozzolans is found to be involved in the direct, nondirect, and, above all, indirect stimulation of the C3A phase of ordinary Portland cement (OPC) saline hydration, because of its high, fast, and early pozzolanic activity. For this reason, its pozzolanic activity is justifiably classified more as specific than generic, intensifying the formation of Fs from the C3A origin of OPC.