The Influence of Concrete Elastic Characteristics on the Impact Noise Insulation of Concrete Floors

The noise insulation characterisation of a bare floor for structure-borne sound is usually based on specific tests made in accordance with the established international standard EN ISO 20140 and the structure-borne noise insulation index calculated according to standard EN ISO 20717. For bare concrete floors of the same type, which one might suppose would have identical acoustical performance, different impact sound insulation frequency spectra may be obtained if the concrete at the zone where the impact hammer strikes is of different type. This situation is particularly the case for bare floors which have levelling layers of floor screeds.

This work presents an analytical study of the influence of the elastic characteristics of the concrete used in the area of the bare floor where the hammer of the standard tapping machine strikes (whether it be the structural concrete of the slab or a light concrete screed applied as a levelling layer), on the impact noise insulation spectra, and on the corresponding value of the structure-borne sound insulation index.

The study firstly involved theoretically modelling the applied impulsive force spectrum of the hammer impact. Secondly, the modelled force spectrum was compared with the results of impact characteristics obtained using several shock tests on defined specimens, for which the effective impact force is determined. Finally, using these resulting force spectra, some simulations on a standard floor were performed to determine the changes in the response spectra, and the corresponding insulation index for structure-borne sound. Some additional considerations and conclusions are also presented.