Strength and durability studies on Mt. Etna volcanic precursors-based geopolymers

In recent years, volcanic pyroclastic residues from Mt. Etna (ash and paleosoil named “ghiara”) have been widely employed as feedstocks in the alkali activation process [1, 2]. In the optic of building and restoration applications, strength and durability of volcanic ash and ghiara-based geopolymer (binders and mortars) have been investigated in terms of structure degradation, efflorescences development and water moisture transfer after being exposed to natural weathering [2]. Ultrasound Pulse Velocity, specific weight, Brazilian Disk and Digital Image Correlation together with Dynamic Vapor Sorption (DVS) techniques have been used in order to understand the structural properties of geopolymers before and after the atmospheric exposure. In addition, DVS results of pure salts, (i.e. sulphates and carbonates) which can often occur as efflorescence, were compared to the results obtained on geopolymers. Overall, by comparing the results obtained on unexposed and exposed samples, it was found that volcanic ash-based geopolymers have shown a better reaction to weathering in the hot summer Mediterranean climate zone.