The effect of natural fibres on geopolymers made using Mt. Etna volcanic ash as precursor

In the last years the awareness of environmental issues has led to the development of eco-friendly materials that could combine high performance products with the possibility of the re-use of waste materials in both construction and restoration field (Barone et al., 2020a). For Catania the disposal of a large amount of volcanic ash produced by Mt. Etna is seen as a problem. The possibility to turn a waste material into a resource could be a substantial benefit (Barone et al., 2021 b; Occhipinti et al., 2022). Moreover, the city is located on an active seismic zone so high-quality construction materials are required. Alkali activated materials have favourable properties such as low curing temperature, recyclability, low cost of the precursors, thermal stability and low density, making them a valid alternative to traditional OPC. Despite these excellent qualities their brittle behaviour imposes constraints in structural design. To enhance the strength of the geopolymer matrix, both organic and synthetic fibres can be added to the binders to improve mechanical properties (Serdan et al., 2013). Two types of organic fibres in different length and amount, were used to reinforce Mt. Etna volcanic ash-based geopolymers. Flexural and compressive strength tests were carried out to compare the mechanical properties of geopolymer composites by using different types of fibres. Moreover, samples were analysed by electron microscope to evaluate the gel formation and the adhesion of the geopolymer matrix to the fibres net. Preliminary results have shown that the addition of fibres enhances the flexural properties and reduces the shrinkage of the system. This research, funded by the PNR “Advanced Green Materials for Cultural Heritage” project aims to develop natural fibre-reinforced geopolymers for retrofitting seismic areas.