Prediction of the sound reduction index of clay hollow brick walls

Abstract

Clay hollow brick walls are still popular in building industry, but the prediction of their sound insulation properties is not straightforward due to their inhomogeneous and anisotropic characteristics. In this article, a classic approach has been used to determine the sound transmission coefficient of brick walls, assuming an orthotropic behaviour and deriving the mechanical and dynamic characteristics from datasheet information. Different types of walls with horizontal and vertical mortar joints have been analysed. Experimental measurements of the sound reduction index carried out according to ISO 10140-2 standard have been performed, and the resulting values are compared with the predictions in the proposed model. It was found that the sound reduction index can be fairly predicted in the low-frequency range and it is correctly predicted in the mass law region, whereas in the high-frequency range the inner block structure is responsible for a loss of performance which is difficult to predict with the analytical methods.

Sound insulation of a hollow concrete blocks wall made with construction and demolition waste and wood-based panels as linings

“…The prediction of sound insulation can be reached using the equations related by Granzotto et al 38 with some complementary information given by the literature for an orthotropic plate. Initially vertical and horizontal compressive strength of the blocks were measured, described as f b k and f ′ b k respectively.…”

“…The equable modulus of elasticity can be written as function of the in-plane ( φ ) angle by the equation (5): 38,41,42…”

“…Where the elasticity moduli can be noted in their complex form as indicated by equations (6) and (7): 38…”

“…Where m ′ is the mass per unit area of the wall, f is the center frequency within the one-third octave band interval and η i n t is the internal loss factor, set as 0 . 01 for concrete. 7 The shear modulus ( G φ ) and the bending stiffness ( B φ ) functions can be written according the equations (9) and (10): 38…”

“…The low sound insulation performance at the low-frequency range is also related to the orthotropic behavior of the hollow brick wall, corresponding to the coincidence zone, as described by Granzotto et al 38 The mass law can not be applied in order to predict the sound insulation for a wall built with the tested blocks. As shown by Figures 17 and 18 it overestimated the sound reduction indexes.…”