The Recycling and Reuse of Natural Materials: Sound Absorbing Box Patterns That Use Waste from Olive Tree Pruning

The agricultural activity of pruning olive trees generates waste which, due to long-standing practices and unawareness of the consequences, are burned on site, thereby producing CO2 emissions in the atmosphere. Therefore, in order to prevent environmental pollution and a waste of resources, the aim of this research investigation was to highlight some alternative uses of the pruning of olive trees waste. This work focuses on recycled and reused by-products as a secondary raw material for the implementation of interior components that can be used for indoor acoustic correction purposes and evaluates their potential as absorbing materials, without overlooking the aesthetic dimension. In this paper, different configurations based on plywood frames with loose olive pruning chips used as a filler, namely, modules and sub-modules, were investigated. Moreover, other technological details, that is, the influence of a Tissue-Non-Tissue (TNT) layer and a spray film coating applied over the external surface of the loose material, were measured. Sound absorption measurements were conducted inside a small-scale reverberation room (SSRR) and the experimental results demonstrated that the samples, for the given thickness, have weighted sound absorption values (alpha(w)) of between 0.15 and 0.35 and single third-octave band values that can reach higher values than 0.50 above 500 Hz. The frequency curves and weighted values of the samples in which the influence of TNT and the spray film coating were tested remained unchanged. This is a design aspect that allows absorbing surfaces to be modeled and integrated with existing walls, while maintaining the acoustic performance and the specific aesthetic features of the loose material

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

Characterization of a hybrid nano-silica waterborne polyurethane coating for clay bricks

A transparent hybrid organic–inorganic waterborne coating was evaluated for the protection of clay bricks. The nanocomposite film was prepared by combining an environmentally friendly process based on UV-curing of water-based acrylic resins and a mild thermal treatment to form nanosilica in situ from alkoxysilane precursors. Coated and uncoated facing bricks were compared by scanning electron microscopy, surface profilometry, water wettability, and capillary rise tests. The hybrid coatings act as a moderate water repellent; interestingly, no appreciable alteration of the aesthetic properties of the brick was observed, in particular no gloss or color change appeared after the treatment

A Novel Photo-bioreactor Application for Microalgae Production as a Shading System in Buildings

The optical performances of plastic bag photo-bioreactors for microalgae production as shading systems for windows were assessed. The micro-algal growth rate and the light transmittance of prototypes were monitored in a photo-incubator and in a real room. Daylight in the room with algae and the energy demand for lighting EDl were then simulated using Daysim and compared to the case of a traditional venetian blind, for two different Italian sites (Turin, Palermo) and 3 orientations (south, west, north). It was found that the algae-system resulted in increased daylight level and glare and in decreased EDl

A Preliminary Study on Light Transmittance Properties of Translucent Concrete Panels with Coarse Waste Glass Inclusions

This paper investigates the potential reuse of coarse glass wastes as insert in a high performance cement matrix to produce translucent concrete panels for architectural applications such as interior walls. The effects of the addition of glass scraps on chemical and optical properties of concrete were studied. Alkali-silica reactivity resistance tests were carried out to evaluate the reactivity between amorphous waste glass and alkaline concrete pore solution. Light transmittance LT was evaluated through Radiance simulations and measurements on sample prototypes. The increase in the amount of daylight in a sample room and the reduction in the energy demand for lighting EDl were investigated through Daysim simulations. Compared to two opaque side walls, the use of two translucent concrete walls with a LT of 5% allowed a reduction in EDl up to 16% in Palermo (L=38.3°N)