What is the purpose of the mortar

Mortar: This is the difference to plaster and cement

Mortar, plaster and cement consist of the same raw materials. All building materials are gray, viscous, are mixed with water and are used for filling, mending or gluing. Nevertheless, there are important differences between the building materials, because their properties determine their use.

Mortar: This is the difference to plaster and cement
Mortar: This is the difference to plaster and cement

Lime, clay, sand and water: the building materials mortar, plaster and cement have the same, clear basic recipe, they are all gray and they are used for building. The difference lies in the aggregate and the aggregates, which give the building materials and types of mortar certain properties such as a longer processing time, elasticity or a thin or thick consistency.

Cement as the most important binding agent

Cement consists largely of burnt, ground lime and clay. Also quartz sand and some iron ore. After burning at well over 1,000 degrees Celsius, cement clinker - mineral spheres - is produced. Depending on the type of cement, other additives are added to this and everything is ground to a fine powder. Trass cement, for example, is made particularly resistant by a certain volcanic ash.

Cement has a different function than mortar and, as a binding agent, bonds different types of rock to form a hard mass. After setting, cement, water, sand and gravel are used to create concrete.

Mortar with many uses

If you leave out the gravel in concrete and mix only water, sand and cement, you get mortar. This may have a maximum grain size of 4 millimeters and, in contrast to coarse-grained concrete, can also be used as a thin-bed mortar to fill fine joints. However, mortar is less pressure-resistant than concrete. Cement, lime or a mix of both are used as binding agents in the mortar.

Mortar acts as an adhesive, which can also be very thin. Other additives are possible, for example as antifreeze or to make the mortar water-repellent. Like concrete, mortars are available as ready-mixes that can be mixed with water. Since mortar is crucial for building stability, its use as a plaster and wall tie is regulated by its own standard - DIN EN 413.

What types of mortar are there?

With types of mortar one means the respective use of a mortar, with mortar groups the different compositions. Depending on how it is used, there is masonry mortar that glues loose stones into solid masonry or fills gaps in walls and walls, grout for filling joints between natural stone slabs or mortar that can be used to glue floor or wall tiles.

Masonry mortar or roofing mortar - special additives determine the purpose for which a mortar is suitable. Masonry mortar is divided into light mortar, thin-bed mortar, normal masonry mortar and facing mortar. The normal masonry mortar is divided into three mortar groups. The name always comes from the main binder - lime mortar, lime cement mortar or cement mortar. With lime mortars, for example, lime in the form of hydrated lime or quick lime serves as a binding agent and ensures that the mortar can be processed very easily. The compressive strength can also be read from the mortar group:

  • Mortar group I: Lime mortar consists of sand and lime and has a low compressive strength. You cannot use it to build walls higher than two floors. The mortar is easy to work with and is particularly suitable as an interior plaster.
  • Mortar group II: Lime cement mortar contains lime and cement in different weights. Its cement content makes it resistant, the lime content makes it easy to work with. The mortar is ideal for masonry, but not for vaults or reinforced masonry.
  • Mortar group III: Cement mortar has the highest compressive strength and is also suitable for reinforced masonry. Cement mortar contains five parts sand and one part cement. Such a mortar sets quickly and is very robust.

Home improvement projects with mortar

Plaster does this job

In principle, plaster is suitable for mortar pimped up with special binders and aggregates and for coating interior and exterior walls. It smooths finished walls as a finishing touch, protects them and beautifies them. There are base and finishing plasters as well as exterior plasters and interior plasters. The binders can be organic or mineral, most commonly lime and cement for exterior plaster, and plaster of paris and clay for interior plaster.