Hard shell, soft core – stuffed masonry bricks
Part 1 – Progress and thermal insulation

»1 Schematic representation of the equivalent thermal conductivity of an insulating material as a function of apparent density, showing the individual contributions to the overall equivalent thermal conductivity (from AGI Arbeitsblatt Q132 [3])

»2 Thermal resistance of an air- or insulant-filled chamber, plotted as a function of chamber slot width

$»3 One-dimensional assessment of a succession of webs and chambers: numerous small chambers (yellow background) and few large chambers (green background), for a 30-cm brick with a 60% core-hole fraction (18-cm chamber width and 12-cm web, cumulated)$

»3 One-dimensional assessment of a succession of webs and chambers: numerous small chambers (yellow background) and few large chambers (green background), for a 30-cm brick with a 60% core-hole fraction (18-cm chamber width and 12-cm web, cumulated)

»4 Three-dimensional model for numerical calculation and representation of heat-flux density in a stuffed brick

The thermal evolution of masonry bricks over the past 10 years has engendered the widespread dissemination of stuffed masonry units in general, but most notably of stuffed bricks. These products are able to satisfy the energy performance targets of the German federal government and the provisions of the German Building Energy Conservation Ordinance (EnEV) for new construction. This contribution surveys the design and development of stuffed bricks in recent years and describes their physicostructural context with regard to thermal insulation.

1 Market overview and development

With the exception of aerated concrete, which is still only available as a homogeneous mass, the market is full of masonry bricks and blocks (made of clay or lightweight concrete) with fillings of various kind and material. Many producers have developed their own, new masonry unit geometries specifically for filling with insulating material. Significant pertinent developments by manufacturers of hollow lightweight-concrete blocks, for example, extend back to the 1980s. However, it was not until the late 1990s that any particular product – specifically a...