Why is clay used to make bricks

Bricks Can be used in a variety of ways in solid construction

© Ziegelwerke Otto Bergmann

Production of masonry bricks

The raw material for the brick production is clay, which is mined near the surface in clay pits. The clay is crushed and homogenized in the so-called "pan mill" by heavy rollers. If the clay is too rich, it can be thinned by adding sand or lime granules. If higher bulk densities are to be achieved for the production of sound insulating bricks, lime or natural stone powder is added. The prepared clay is then pressed through an extruder and the masonry bricks are cut to the desired size with a wire. The moist bricks are then dried in the drying chamber for between 24 and 48 hours. The bricks are then fired at between 900 and 1200 ° C for several hours.

Bricks are called either Perforated brick or as Solid brick produced. With perforated brick, holes standing vertically (vertically perforated brick) or horizontally (elongated perforated brick) to the support surface reduce weight and improve the support surface.


Clay bricks are characterized by their ability to diffuse and their sound-absorbing properties. The heat insulating properties are, however, only moderate. The thermal conductivity of a vertically perforated brick (1800 kg / m?) Is 0.81 W / mK. The thermal conductivity can be significantly reduced by using so-called porous bricks. Styrofoam balls are added to the clay, which burn up completely during the burning process and leave behind a large number of small air chambers. The thermal conductivity of a light vertically perforated brick (800 kg / m?) is 0.33 W / mK.

The thermal insulation properties of perforated bricks can be significantly improved by filling the holes with a thermal insulation material such as perlite. In connection with the thin-bed mortar method, single-shell wall structures with good thermal insulation are possible.

Masonry types

Block bricks

In contrast to flat bricks, block bricks are not sanded after firing. The surface of these bricks is therefore not absolutely flat, but can have certain unevenness. More mortar must be used to even out these bumps. This has the disadvantage that, on the one hand, more moisture is introduced into the masonry and, on the other hand, the thermal insulation properties are not optimal with a single-shell design. This can be compensated for by using special thermal insulation mortar. Block bricks are cheaper than flat bricks because one less processing step is required.

Block bricks are usually made as vertically perforated bricks.

Plan brick

With flat bricks, the bearing surfaces are ground flat after the firing process. Flat bricks can therefore be laid in thin-bed mortar. When using the thin-bed mortar method, particular care must be taken when laying the first layer of brick in order to obtain an absolutely flat surface. The advantages of the flat brick in connection with the thin-bed mortar method are:

  • It will less mortar needed. This means that less moisture is brought into the masonry. In addition, there is no loss of thermal insulation through the mortar joint.
  • Labor saving. The thin-bed mortar method is more rational.
  • Increased load capacity opposite block bricks.
  • Homogeneous subsoil. The lack of a wide mortar joint allows plastering work to be carried out better.

Flat bricks are usually made as vertically perforated bricks.

Solid brick

In contrast to perforated bricks, solid bricks have no perforations. They are therefore significantly heavier and have a higher thermal conductivity. That is why they play a certain role today primarily as clinker bricks.

Adobe bricks

Mud bricks are air-dried and not fired. We use them as infills for wooden stands.


Clinker is a brick in which the pores are closed by sintering at very high firing temperatures. Clinker bricks are mostly used as facade bricks. They are manufactured both as solid bricks and as perforated bricks. Clinker bricks are frost-resistant but do not have good thermal insulation properties.

Recommended manufacturers


Bricks from Schlagmann filled with perlite with high thermal insulation performance. [more]