Preliminary tests showed that the typical geopolymers (Koranel slag + potassium hydroxide) cannot withstand the high temperatures required, and undergo yielding phenomena (Figure.1).

In order to address this issue, NTUA team designed a new recipe, after performing the chemical and mineralogical analyses of the raw materials and by examining the ternary diagrams. The designed recipe utilizes pure alumina for fire resistance and Al powder for reducing the density (Figure. 2).