The use of Mount Etna volcanic ash in the production of bricks with good physical-mechanical performance: Converting a problematic waste product into a resource for the construction industry

Volcanic ash emissions are responsible for serious damage to buildings. They can also affect vehicle traffic, cause airport closures and may be hazardous for human health. To verify the effects of the potential addition of this residue to the mixture used in the production of bricks, a detailed study of the clayey material, the volcanic ash and the bricks fired at 800, 950 and 1100 °C was conducted, assessing chemical, mineralogical, physical, mechanical and durability aspects. The addition of 10–20 wt% of volcanic ash delayed the appearance of new phases during brick firing and made them less porous. The bricks maintained their orange colour and became more compact as the firing temperature increased due to sintering and vitrification processes. The addition of volcanic ash reduced the strength of the bricks although the values were always above the limits recommended for construction work with ceramic materials. Bricks with added volcanic ash increased their resistance to decay due to salt crystallization and the general behaviour of the bricks improved when they were fired at high temperatures.