Multi-technique investigation of calcium hydroxide crystals at the concrete surface

Abstract

The durability and aesthetic qualities of high-performance concrete, which makes it particularly suitable for architectural applications, are constantly compromised by environmental aggressions. In this study, an innovative solution was developed to protect the concrete from these aggressions, which consists of growing a mineral coating on the concrete surface. The coating is composed of layered calcium hydroxide crystals, whose nucleation and growth are triggered byvarious non-ionic surfactants (the details of the process will not be presented). This paper describes the procedure used to investigate the structure of the formed crystals. Scanning Electron Microscopy and optical microtopography were used to determine the morphology of the crystals. Image analysis allowed the quantification of their amount, size and shape. The contribution and limits of each technique are discussed.

The effects of heating on the physicochemical properties of tricalcium silicate root canal sealers

“…This deposition was less intense and occurred in the form of small dispersed crystals on the surface of Bio-C, however, still present in a significant amount when the sealer was heated. The heating of the bioceramic sealers probably accelerated the growth of calcium silicate hydrate (C-S-H) promoting the occurrence of a greater number of hydration nuclei with the typical deposition of calcium hydroxide crystals 25 . The characteristic hexagonal shape of the crystals, as well as their layered organization, allow them to be identified as calcium hydroxide 25 .…”

“…The heating of the bioceramic sealers probably accelerated the growth of calcium silicate hydrate (C-S-H) promoting the occurrence of a greater number of hydration nuclei with the typical deposition of calcium hydroxide crystals 25 . The characteristic hexagonal shape of the crystals, as well as their layered organization, allow them to be identified as calcium hydroxide 25 . This was confirmed by the EDS analysis, showing the presence of a high peak of calcium ( Figures 1 , 2 , 3 ).…”