LIGHTWEIGHT SCREEDS MADE OF CONCRETE AND RECYCLED POLYMERS: ACOUSTIC, THERMAL, MECHANICAL AND CHEMICAL CHARACTERIZATION Francesco Asdrubali Francesco D’Alessandro Samuele Schiavoni Giorgio Baldinelli Department of Industrial Engineering, University of Perugia, Italy. Summary The paper concerns the use of granulated polymeric materials obtained from sheaths of electric wires, mixed with concrete and water to produce under-floors with good sound and thermal insulating performance. This is a possible solution for the re-use of this typology of waste, so to avoid the disposal into landfills. Several configurations of the product were tested in the reverberation rooms of the Laboratory of Acoustics according to ISO 140-8 standard, in order to fully characterize the sound insulating properties; the thermal conductivity was measured through the hot box of the Laboratory of Thermotechnics, according to EN 1934. Also mechanical tests were executed in terms of dynamic stiffness according to EN 29052-1 and compressibility according to EN 12431; a chemical analysis completes the investigation of the mixture. The results show that the product presents satisfying thermal performance, together with good mechanical properties; the chemical analysis of the loose polymers underlined the presence of some chlorinated and polycyclic hydrocarbons. From the acoustic point of view, the sound impact reduction index directly evaluated both with a direct test in the reverberation room and with the indirect estimations through the dynamic stiffness gave results comparable with common materials used for screeds. When the material was tested in conjunction with other typical components of floors, the sound impact reduction index showed poorer performance, underlining that the optimization of the acoustic properties has to be done taking into account of the combination with other floor materials. PACS no. 43.40.Kd, 43.50.3Jh 1. Introduction 1 Energy consumption in the building sector can reach up to 40% of the total energy demand of an industrialized country. For this reason, green building strategies can be extremely effective as far as fossil fuel savings and greenhouse gas reduction. Sustainable materials - made from natural or recycled materials - can play an important role, since less energy is generally required for their production than that needed for conventional materials. In the last years a great attention has been focused on “green” materials, especially in the building sector. 1 (c) European Acoustics Association An increasing attention has been turned to natural fibres as alternatives to synthetic ones, in order to combine high acoustic and thermal performance with a low impact on the environment and human health. Recycled materials, such as recycled plastic fibres and recycled rubber mats, can even be regarded as a sustainable alternative, as they contribute to lower waste production and use of raw materials [1]. In particular the recycle of electric wires has grown largely because of the continuous increase of copper value; as a consequence, a huge amount of waste deriving from the poorer part of the cables, such as the polymers of sheaths, is produced and any application that could employ this kind of material becomes of great interest. (c) European Acoustics Association, ISBN: 978-84-694-1520-7, ISSN: 221-3767 821