Cement screed
Cementitious flow screed (CTF)
Cementitious flow screed (CTF) is a variant of cementitious screed. The main components such as cement and aggregate are the same, but the cement flow screed also contains superplasticizers, which give it its special, flowable consistency. Ideally, the grain size of cement self-levelling screed is smaller than that of other cement screeds. This avoids inhomogeneities in the screed body.
Cement screed is a CE-marked screed mortar in accordance with DIN EN 13813. Its application is regulated in the DIN 18560 standard.
Cement self-levelling screed has two important properties: it is self-levelling and self-compacting. This means that it spreads almost automatically and achieves a high density. Compared to conventional cement screed, a thinner layer thickness is required for the same load-bearing capacity.
Areas of application for cement flowing screed
The most common areas of application for cement screed are living spaces. As the material is moisture-resistant, it can also be laid in damp rooms such as bathrooms or saunas, cellars or garages. It can even be used in permanently wet areas such as swimming pools. It can be combined with all additional floor coverings and also with underfloor heating. Of course, it can also be used in commercial buildings such as schools, halls or workshops.
Note: However, cement self-levelling screed is not suitable for outdoor use as it is generally not sufficiently resistant to frost and de-icing salt.
Different installation techniques are used depending on the area of application.
Laying techniques for cement self-levelling screed
In residential construction, cement screed is mainly used as a floating screed on top of a layer of insulation. It is also popular in combination with underfloor heating. In larger buildings that are used commercially, on the other hand, it is common to use the cement flowing screed as a bonded screed or alternatively on a separating layer. The use of surface-finished exposed screed is also possible, but is rarely used.
Practical: Cement flow screed can be laid with comparatively little physical effort. It is applied to the substrate with a watering hose and then spread with a buffing rod. Thanks to its flowability, it reaches every corner almost by itself and is distributed over the entire surface at a uniform height.
What to look out for when installing cement self-levelling screed
Cement flow screed is available in two variants:
- Factory-fresh mortar: supplied ready to use from the truck mixer
- Ready-mixed dry mortar must be mixed with water on site before laying
Laying cement self-levelling screed requires knowledge and skill. This is because the material tends to dry out on one side and crack. This makes professional application all the more important. On the one hand, overwatering must be avoided at all costs. On the other hand, expansion joints must be planned to reduce the tendency to crack.
Not only the thickness of the screed board, but also the ambient conditions can influence the drying time. In general, it is important to ensure that the temperature is not below 5 °C during installation. Higher temperatures and air exchange rates shorten the drying time, while high humidity extends it. The drying process can be accelerated by sanding the surface.
The advantages of cement flowing screed
Thanks to its more fluid consistency compared to conventional cement screed, less physical effort is required when applying cement flow screed. This is because it is applied using a pump and a hose, and gravity alone ensures that an even, perfectly level surface is created (automatic leveling).
However, cement self-levelling screed is not only self-levelling, but also self-compacting. The comparatively higher density goes hand in hand with a higher load-bearing capacity, meaning that the screed can be laid thinner. This means not only lower material consumption, but also a shorter drying time.
In addition, cement flowing screed - unlike other flowing screeds such as calcium sulphate flowing screed - is resistant to moisture. And it is characterized by early readiness for covering and very good heat transfer. This makes it ideal for use in combination with underfloor heating.
Your contact for work with cement flowing screed
Comprehensive know-how, regular further training for our employees and over 25 years of experience in laying screed are the basis for our professional screed work. Your satisfaction is our top priority, which is why we rely on strict quality management to ensure the high standard of our work. We are proud of this - just as we are of our passion and reliability, which each and every one of our employees stands for. See for yourself and let us advise you. We are happy to assist you with screed work of all kinds - from planning to execution. We look forward to hearing from you!
Questions and answers about cement flowing screed
Cement screed is mainly used in residential construction. It is suitable for all rooms, including rooms with high humidity or wet rooms. It is also used in commercial properties.
A w/c ratio (water/cement ratio) of slightly less than 0.80 is considered ideal, which means that the ratio of water to cement is 80:20. This type of screed has very good flow properties and is therefore very easy to work with.
The compressive strength depends on various properties of the material. In addition to the strength class and the water/cement ratio, this also includes the adhesion of the cement paste and aggregate and their degree of compaction. A cement flow screed with an optimum w/c ratio can have a compressive strength of 25 N/mm² after curing.