Valorization of natural waste materials: volcanic ash from the 2021 eruption at Cumbre Vieja (La Palma Island, Spain).

In this work, we evaluate the suitability of volcanic ash from Cumbre Vieja volcano at La Palma Island (Spain) as raw material for alkali activation process. The aim of this work is valorize what commonly constitutes a natural waste material in active volcanic areas and use it for building or conservation purpose. To date, ash deposits constitute a serious problem not only because they are difficult to dispose, but also because it is not clear how to use them. During last eruption, started the 19th of September 2021, pyroclastic fallouts covered wide cultivated and residential areas within a radius of tens of kilometers from the eruptive center. To give value back to this natural waste, we propose to employ it for the production of low energy consuming and cost-efficient geopolymers. Indeed, volcanic ash has been proved as an efficient precursor for geopolymer production as demonstrated by recent formulations using Etnean pyroclasts [1,2,3]. For this reason, ash from Cumbre Vieja 2021 eruption has been sampled from proximal to distal areas of the emission point and will be characterized by morphologic, mineralogical and chemical techniques in order to define the best mix design for the geopolymer formulation. We expect good results in terms of mechanical and physical properties of these materials with promising application in building construction and restoration field.