*2.2. Microscopical Characterization*

A scanning electron microscope (SEM) was used to show magnified images of the aggregates and of the cement composites. For this purpose, a FESEM-EDX Carl Zeiss Sigma 300 VP (Carl Zeiss Microscopy GmbH, Jena, Germany) electron microscope was used and the samples were sputtered with gold after immobilization onto aluminum stubs (Sputter Quorum Q150 Quorum Technologies Ltd, East Sussex, UK). The elemental composition of the different organic and inorganic areas of the samples was obtained by energy dispersive X-ray (EDX) analysis (Oxford Instruments, X-Max 20, Abingdon-on-Thames, UK). Specifically, sand composition was: C (4%), O (52%), Si (35%), Ca (2%), end-of-life tyre rubber composition was: C (25%), O (70%), S (1.5%), recycled porous waste glass was: Na (14.8%), Mg (2.1%), Al (3.5%), Si (66%), K (1%), Ca (12%), cement paste composition was: C (4.2%), O (40%), Si (7.6%), Ca (44%), Fe (1.5%), Al (2.5%). A homemade system (premier series dyno-lyte portable microscope and background cold lighting) allowed us to evaluate the wettability of the specimens, which was carried out after deposition of a drop of water onto the side and fracture surface of each sample.
