Francesco D'Alessandro

Sound absorbing properties of materials made of rubber crumbs

Recycled tyre granules can be used for manufacturing acoustic insulating and absorbing materials, with applications in buildings and road barriers. Therefore, the production of these materials is a valid alternative to the disposal into landfill or incineration of used tyres. This paper presents the results of sound absorbing coefficient measurements of several samples manufactured at the Acoustics Laboratory of the University of Perugia. The sound absorbing panels were produced by mixing rubber crumbs and an adequate binder in a proper proportion and then by compacting the obtained mix. The methodology used to evaluate coefficient of absorption coefficient is indicated in ISO 10534‐2 standard, thanks to an impedance tube. The influence on the absorption performance of granules size, binder concentration, thickness and compaction ratio of the samples was investigated and an optimization process was carried out, in order to produce a sample with satisfying acoustical performances.

A review and comparative analysis of European priority indices for noise action plans

The European Union has provided in recent years (and is going to update) several tools to harmonise noise mapping methodologies through directives and guidelines. Unfortunately the same efforts have not been put in the harmonisation of approaches for Noise Action Plans, the effective instruments to manage noise impacts. As a consequence, each European Member State at national or even at local level defined its own methodology, usually considerably different one from the others. Nevertheless, the most common approach to deal with noise impact at a policy, economic and strategy level is the use of priority indices focused to highlight areas or buildings where mitigation actions are more advisable or urgent. The aim of the present research is to provide a review of the most used European priority indices and also to test some of them in a study area. The comparative analysis demonstrates that the method chosen for the prioritisation deeply affects the ranking of the areas where noise measures need to be realized. Some methods tend to give high priority to noise sensitive locations, others to high populated buildings, and others to the areas where noise levels are high. The study proves how much common approaches are needed also for Noise Action Plans to reach a coherent noise policy within European boundaries.

How reproducible is the acoustical characterization of porous media

There is a considerable number of research publications on the characterization of porous media that is carried out in accordance with ISO 10534-2 (International Standards Organization, Geneva, Switzerland, 2001) and/or ISO 9053 (International Standards Organization, Geneva, Switzerland, 1991). According to the Web of ScienceTM (last accessed 22 September 2016) there were 339 publications in the Journal of the Acoustical Society of America alone which deal with the acoustics of porous media. However, the reproducibility of these characterization procedures is not well understood. This paper deals with the reproducibility of some standard characterization procedures for acoustic porous materials. The paper is an extension of the work published by Horoshenkov, Khan, Bécot, Jaouen, Sgard, Renault, Amirouche, Pompoli, Prodi, Bonfiglio, Pispola, Asdrubali, Hübelt, Atalla, Amédin, Lauriks, and Boeckx [J. Acoust. Soc. Am. 122(1), 345-353 (2007)]. In this paper, independent laboratory measurements were performed on the same material specimens so that the naturally occurring inhomogeneity in materials was controlled. It also presented the reproducibility data for the characteristic impedance, complex wavenumber, and for some related pore structure properties. This work can be helpful to better understand the tolerances of these material characterization procedures so improvements can be developed to reduce experimental errors and improve the reproducibility between laboratories.

Assessment of the Performance of Road Markings in Urban Areas: The Outcomes of the CIVITAS RENAISSANCE Project

In the framework of the EU funded CIVITAS plus RENAISSANCE project, a research activity was focused on the definition of a new methodology for evaluating the global quality of the road markings at urban level, both from a technical and an economic point of view, in order to assure road safety. Two innovative indicators were developed: one for the assessment of the technical performance (CIS-Q) and one for the optimization of the budget (CIS-C). In order to rate the global quality of municipal road markings, the performance indicator CIS-Q takes into account all the parameters characterizing the performance of road markings, such as luminance coefficient in day conditions Qd, retroreflectivity in night conditions RL (dry, wet), skid resistance SRT, colour, kind of material and ageing of the pavement markings, traffic volumes, characteristics of road surface and average local weather conditions. The economic indicator CIS-C considers the budget available for the road manager and compares it with the one needed to ensure an adequate level of quality for road markings.

Impact sound insulating performance of access floors

Access floor are raised floor systems consisting of modular panels supported by posts at a certain height to create a gap below the floor surface. Electrical wires and pipes can be placed inside the gap in order to avoid exposed installations and to simplify operations involving the inspection, repair, changing, or adding of system elements. This paper presents the results of the measurement campaign carried out on seven different access floor configurations, obtained by changing different floor elements: panels, surface finishes, damping materials under the posts base. Impact sound insulating properties of access floors combined with false ceilings were also tested and are reported in the paper. The tests were executed in two overlapping reverberating rooms available at the Acoustics Laboratory of the University of Perugia using the procedures given by ISO 140‐6 Standard. The results are expressed in terms of normalized sound impact pressure level Ln and of the corresponding single number index Ln,W.