Acoustic Performance Assessment of Sustainable Acoustic Absorbers Made from Olive Tree Pruning and Pine Waste

This work aims to elaborate and characterize new ecological composite materials from olive trees pruning waste for the manufacture of acoustic absorbers. For this purpose, two samples’ typologies of loose olive tree chips have been considered after applying different degrees of chipping and blending to olive pruning waste. The samples have been compared to a third sample based on pine shavings waste. Firstly, the morphological analysis of the different samples was carried out by micro computed tomography (Micro-CT) scanning. Secondly, the acoustic properties were measured experimentally using impedance tube method, and assessed from air flow resistivity and permeability; the mass transport properties are exploited for the characterization of microstructural parameter, such as tortuosity, effective porosity and pore structure morphology by applying analytical models for fibrous and granular materials. The experimental results demonstrated that the samples, for the given thickness, have single third-octave band sound absorption values that can reach higher values than 0.50 above 1000 Hz. A good match between experimental and analytical models could be found.