The drying process influence on the brick walls sound reduction index: laboratory evaluations and theoretical analysis

Abstract

This paper presents experimental results showing the sound reduction index of different types of brick walls; the analysis was in particular carried out on double walls, single walls, and single walls with external lining. Its main purpose is to find the minimum drying time of the structure necessary to obtain the sound reduction indexes of brick walls as close as possible to laboratory real values. Moreover, it aims at making results of different laboratories as comparable as possible in terms of repeatability and reproducibility. All the fundamental quantities, such as the sound reduction index (R), the weighted sound reduction index (R_{w}), the spectrum adaptation terms C and C_{tr}, and temperature (T) and relative moisture, have been analyzed. A qualitative analysis of the curves slope of the sound reduction index versus frequency has been conducted for each drying time for each type of evaluated wall. The measurements were carried out in the acoustic laboratory of ITC‐CNR (the Construction Technologies Institute of the Italian National Research Council) in Milan, according to the procedures of ISO 140 part 3.