What is a concrete slab
On the one hand, we will define the concrete slab as a smooth and flat surface, a sheet or concrete plate that distributes the weight and loads of the building along the entire support plane, functionally supporting the load. structural.
Concrete slabs are used in almost any type of building such as homes, industrial warehouses or commercial buildings, since they provide resistance and support to the structure they support.

What uses has the concrete slab
Concrete slabs are mainly used as floors or ceilings. They can also serve as a base for other structures. Concrete slabs are also used to level uneven surfaces, such as slopes or poor ground.
Concrete is an excellent building material because it is inexpensive and strong enough to withstand heavy loads and easy enough to handle that anyone can work with it in almost any condition. The concrete slab is one of many options when deciding which type of concrete best suits the needs of your project.
What is a concrete screed
A concrete screed is a solid, flat and horizontal surface built with concrete, which may or may not have mesh, but which has no structural load-bearing function.
Concrete screeds are elements unrelated to the calculation of building or construction structures, they are only made to give firmness or provide a firm and flat surface to certain elements or create strong slabs with a material that is such as concrete.
They normally serve to support floor finishing solutions such as tiles, porcelain, ceramic, wood or any other material that acts as a floor.

Differences between slab and screed concrete
As we have seen, they are similar solutions in terms of material (identical in this case, being concrete in both cases), and even in terms of internal structure, since both can have a mesh or rebar structure equally, but they differ in that the slab is a structural element within the concrete construction project, while the screed does not have that function.
The slab is an important part of any structural calculation project, since it will support loads like any other element (pillars, beams…) and the thickness and robustness of said slab must be calculated, together with its reinforcement.
On the other hand, the screed does not appear in any structural calculation beyond a simple interpretation of the weight it can support, such as when making a screed to put a heavy item on top such as a vehicle.
Also, as can be taken from CTE DB HS-1, the slab is made of reinforced concrete, while the screed is made of mass concrete.
Another difference is that the screed is always supported on the firm ground, hence it is not included in the calculation of structures, but not the slab, which may or may not be supported.

Differences with screed floor or self-leveling mortar floor
This is a substantial difference, since it is not made of the same material nor is its use and function the same as a slab or a screed.
A self-leveling mortar floor can really be applied on a concrete screed or slab, or on another resistant material to give a solution to a floor finish that can be applied for a certain function, but it is not even about concrete , nor does it have any structural function within a construction project.
Example of slab, screed and self-leveling mortar floor
A very clear example is given in a house, where we can easily find the 3 commented types:
- Concrete slab in housing: It is found, for example, in the physical separation between the ground floor at ground level with a garage, also called wrought iron.
- Self-leveling mortar floor in a house: For the installation of underfloor heating, the entire pipe system is placed on the slab, and this installation of self-leveling mortar tubes is covered up to the finished floor , on which the final tiles will be placed.
- Concrete screed in a home: A screed can be built in a garden to be able to support non-structural weights or, for example, to make an outdoor parking lot and be able to support the weight of a vehicle.