Synthetic ettringite in solutions containing chloride ions

Abstract

The ettringite, Ca6Al2(SO4)3(OH)12·26H2O, is a mineral of esteemed importance for civil construction because it is one of the constituents of concrete. This mineral can be naturally found in nature, as well as it can be one of those resulting from the hydration of cement. This mineral is one of the first minerals formed in cement hardening and its formation during hardening is very important for controlling the setting and the time of use of the material until its final hardening, but this mineral can be formed delayed after the already hardened concrete when there are failures in technological control or through the infiltration of sulfate by external sources leading to unwanted expansions in its structure. Due to the difficulty of finding this mineral in a pure form in nature, methods of synthesizing this mineral have been developed, which makes its development easier, as well as ease of substituting some constituent elements for the most diverse purposes. This work sought to analyze the role of chlorine at different concentrations in the structure of ettringite, as well as its influence on its stabilization through the saccharate method. The synthesis of ettringite was successful and chlorine was adsorbed on its structure. It was observed that the higher the concentration of chlorine ion, the greater the stabilization of ettringite and that the presence of chlorine ion influenced the parameters of the crystal structure of this mineral. From the research presented and discussed in this dissertation, we can conclude that chlorine influences the stabilization of the mineral ettringite.