Chemical, Phase Compositions and Porosity Structure of the Plinth Brick of the White Tower (Greece) of Age Greater Than 450 Yr

Abstract

Oxide chemical analysis of White Tower samples showed that the major oxides (content > 5%) are, %: SiO₂–50.07; Al₂O₃– 16.3; Fe₂O₃– 7.04; CaO – 9.08. The loss on ignition is 11.32. In addition, elemental analysis determined a heightened carbon content carbon – 9.59%. The heightened carbon content (9.59%) in the inclusions attests the introduction of fuel into the green body, which increases the porosity of the articles and promotes uniform sintering of the ceramic, and the heightened content of alkali oxides (R₂O > 3 – 4%) promotes the formation of a glass phase up to 1000°C. X-ray phase analysis showed the presence of anorthite, hematite, and wollastonite, which promotes greater strengthening. Moreover, the presence of isometric pores and oval closed porosity in the ceramic samples increases durability.