Improved sound insulation of sand-lime bricks via the modulus of elasticity


Besides the mass per unit area, the material stiffness determines the sound insulation of masonry. In the current DIN 4109 - "Sound insulation in building construction" the sound insulation is calculated on the basis of the mass per unit area. The aim of this research project is to increase the sound insulation of sand-lime masonry by increasing the stiffness of the bricks, while maintaining the same mass per unit area. The stiffness increase is achieved through targeted and cost-effective optimisation of the manufacturing parameters.

Research Question

Can the modulus of elasticity of the sand-lime brick be increased, for instance by the selection of appropriate raw material, a reduction of the cavity volume, an increase of packing density and/or compaction?


The project is divided into a total of five work steps:

In investigation section A, measurement data of the acoustically relevant parameters (dynamic modulus of elasticity, longitudinal wave velocity cL, dissipation factor η and bulk density ρ) of sand-lime bricks are collected and a correlation with the production parameters is determined.

Subsequently, in investigation section B, bricks are produced in small series with traditional and theoretically optimised formulae and examined in the laboratory with regard to packing density, chemico-mineralogically characterised and the acoustically relevant parameters determined.

In investigation section C, production trials of the optimised bricks are carried out in two sand-lime brick plants. The sand-lime brick samples are also examined acoustically and in terms of building materials.

For investigation section D, walls are installed in the wall test rig of the HFT and measurements of sound insulation and other acoustic investigations are carried out.

Finally, a practical engineering model for the prediction of the sound insulation from the raw material parameters will be developed in investigation section E.

Targeted results

The aim of the research project is to develop masonry walls made of sand-lime bricks which have a higher sound insulation than the mass curve defined in DIN 4109-32. The optimisation with regard to the improved sound insulation also leads to a more precise calculation of the flanking transmission and thus also to increased planning reliability for sand-lime brickwork.

ManagementProf. Dr.-Ing. Berndt Zeitler
Partner Forschungsvereinigung Kalk-Sand e.V.
Duration01.01.2018 – 30.06.2020


Name and position Field Email and phone Room
Professor, Mitglied IAF Direktorium Studienbereich Bauphysik +49 711 8926 2507 7/104
+49 711 8926 2756 7/113
Akad. Mitarbeiter Fak. B - Bauphysik +49 711 8926 2881 7/115
Bauakustik +49 711 8926 2836 7/115