Thermo-mechanical characterization of insulating bio-plasters containing recycled volcanic pyroclasts

Aim: The research proposes the reuse of volcanic wastes in the production of lightened and insulating bio-plasters. Introduction: The goal is the production of a novel sustainable construction material that reduces the environmental impact. Methods: Four mixtures were designed. The recycled Volcanic Ash was used in combination with two bio-compatible binders; basically Natural Hydraulic Lime (NHL) or calcium hydroxide blended with a commercial Portland cement (CH-CEM). To improve thermal properties, CH-CEM mixtures were treated with an Air Entraining Agent (AEA) in two different percentages and a breathable resin (R). The main physical, mechanical and thermal properties were experimentally determined. Results: The results of such analysis indicate that the mixture NHL, realized using hydraulic lime as a binder, do not satisfy the threshold of the water absorption coefficient, exceeding the limit established by UNI EN 998-1 standard. Conclusion: On the contrary, one of the mixtures CH-CEM, containing both AEA and R, is suitable for use as lightweight plastering mortar and also satisfies the requirements for insulating mortars.