Different brick types
It used to be customary to classify brick types according to the region of origin. This method of classifying is basically obsolete, since the brickyards in all regions are subject to the same production standards. It is better to classify the brick products according to their types.
The “full brick” is a brick with a perforation volume rate of less than 15%. A stone with a pair of perforations is thus not necessarily to be regarded as perforated. This type of brick is usually fairly small. This stone is usually very hard, easy to use and frost resistant.
As “perforated stone” is considered compliant with European standards when a rate of 15% to 20% is met. Perforated bricks are usually used for interior walls and the inner walls of cavity walls.
Hollow bricks have more than 20% of hollow space. The hollow brick can’t be used for load-bearing walls because it is not strong enough. This is due to the large percentage of hollow spaces within the bricks, which makes it inappropriate to carry large forces.
The advantage of the hollow brick is the low weight and the large dimensions. This makes it easy for the bricklayer to build walls fast. Furthermore, the hollow brick is somewhat better for insulating the heat.
Previously, the term facing bricks was only used to name the ornamental stones on the outside of a building. Nowadays people are more likely to label all frost resistant bricks to be facing bricks. This definition seems too broad, because 75% of all brick types meet these criteria.
Main features of bricks
When constructing a building with bricks there’re many different brick features to take into consideration. Here are the main features:
The pressure resistance of brick depends on the type of clay being used and on the amount of perforations the brick has. Solid bricks have a pressure resistance of at least 150 kg/cm2. The resistance of the masonry is determined by the average resistance of the brick and mortar. Hollow bricks have a lower resistance.
That brick can remain intact for centuries has been proven by countless buildings. There are plenty of varieties available on the market today. Special environments have the need for a specific type of brick, for example frost, chemical or shock resistant bricks.
The shape stability of a brick is achieved by no other material. It has a very low thermal coefficient of expansion and no shrinkage. With brick walls, one can make up to 40 meter walls in length without the necessary need of joints.
Thanks to the high density of bricks it constitutes as a good shielding effect against noise transmission.
Fire safety and fire resistance
Bricks are classified as “non-flammable” or “A0”, some bricks however are more fire resistant than others.
How a brick is made?
Before we zoom-in on the different type of brick types, we’ll look at the process of creating a brick. A brick is created by the baking clay at a temperature of 850 to 1200 degrees Celsius. The process of making bricks out of clay involves the following operations:
- Homogenizing clay
These five basic operations have remained unchanged over the course of sixty centuries. However, the mechanical devices become more frequent in the last hundred years.
In the past, all the clay was excavated by hand. Nowadays the clay is excavated with the aid of the dredging machines.
The clay used to be homogenized by hand, but it’s done by machines these days. Thanks to the mechanization of this operation the quality has been improved greatly.
For up to one hundred years forming bricks was exclusively done by hand. The brick former took a quantity of clay and hit it in a wooden mold window. The clay was “thrown” and not “laid” because by throwing the corners of the bricks provided better clay. Hand-molded bricks are still crafted today, but mostly by machines who create an irregular (grained) surface. The veins are less deep, the angles are sharper and the mechanical strength tends to be slightly higher.
Approximately 90% of the brick is formed by using an extrusion press. With this machine the clay is formed into a long beam. A bunch of wires then cuts the bar into pieces, so that the bricks are formed.
The drying of the clay stones used to be done in the open air. These days this occurs almost exclusively in special drying rooms.
The baking of the stone is the final operation: about 95% of the bricks are baked in so-called continuous furnaces. As a result, the stone is baked at a continuous temperature.