RETRACTED: Influence of polypropylene fibres on the thermal and acoustic behaviour of untreated coal coarse aggregates concrete (Retracted article. See vol. 56, 2022)

This study intends to assess the influence of untreated coal coarse aggregates (UCCA) and polypropylene fibres (PPF) on the thermal and acoustic performance of concrete. 15 concrete mixes were produced with different PPF contents (0%, 1% and 2% in terms of volume) and UCCA contents ranging from 0% to 30% as replacement for natural coarse aggregates (NCA). Hence, different properties of concrete were evaluated, including bulk density, porosity, electrical resistivity, thermal conductivity, thermal resistance and sound absorption, in addition to common freshand hardened-state properties of concrete. Moreover, new models are proposed to estimate the mechanical, thermal properties of concrete with different UCCA and PPF contents. It was found that the incorporation of both UCCA and PPF substantially improved the sound insulation and noise reduction behaviour of concrete. For example, the frequency of 2000 Hz can be absorbed when 30% NCA is replaced with UCCA and 2% PPF are also added, with an absorption coefficient of 67%.