Investigation of impact sound pressure level reduction of floating floor using the small specimens in the real building

Abstract

Floating floor construction is the best solution for impact sound insulation [1-4]. Weighted reduction of impact sound pressure level ΔLW (dB) for evaluation of the new floor constructions is used. For determination of ΔLW measurements in the laboratory according to LST EN ISO 10140 series standards with big specimens (area >10m2) are to be performed. But it is impractical in the case when quick evaluation of new constructions is needed. The solution could be to do tests using small specimens (area <10m2) in the real building. For that purpose it was decided to perform test using simple floating floor construction: 220 mm hollow concrete slab, 50 mm stone wool and 50 mm sand/cement screed [5]. The dependence of ΔLW value from the size of the specimen (area <10m2) was determined (Fig. 1) [5]. It was decided to repeat the experiment with another floating floor construction often used in new buildings in Lithuania. The floor construction consisted of layers: 160 mm monolithic concrete slab, 50 mm layer of sand, 4 mm resilient layer (SK3 mat) and 50 mm sand/cement screed. The purpose of the test was to look does the same dependence also exist. The impact sound pressure levels (L’n) were measured [6] and evaluated [7] in one-third octave bands in the frequency range from 50 to 5000 Hz of specimens changing its area from 13.8 to 0.5 m2. Results of the research showed that the systematic error δ ΔLW dependence from the specimen area exist in less degree (Fig. 2). Systematic error δ ΔLW increases decreasing the area of the specimen as it was in the previous test but does not meet the previously established log- Law (Fig. 1). So it shows that different floor constructions gives different systematic errors δ ΔLW of the same size small specimen. Therefore, more different floating floor constructions should be tested to determine dependence of δ ΔLW value from the size of the specimen.