In summary
Styrene-butadiene (SBR) is a synthetic polymer that can be added to mortars and concrete as a water-based dispersion. It can contribute to improved adhesion, workability, compressive and flexural strength, resistance to water penetration and durability.
Performance depends strongly on the quality of the dispersion and the correct dosage. Adding more product does not automatically result in better performance.
RC ACRYPLAST is a polymer dispersion for cement-based applications such as bonding coats, cement renders, concrete repairs and water-resistant mortars. Depending on the formulation and application, it can also be used in certain lime- and lime-cement-based systems.
What is SBR?
SBR stands for styrene-butadiene rubber. It is a synthetic copolymer that is generally used in construction products as a water-based polymer dispersion.
When an SBR dispersion is added to a cement- or lime-based mortar, the polymer component forms a structure within the mortar as it dries and cures. This can improve various properties of the mortar.
The dosage plays an important role. A dosage that is too low may not provide the desired effect. A higher dosage does not automatically lead to better performance.
What does SBR do in mortar?
A polymer dispersion can give a conventional mortar additional properties.
Improved adhesion
SBR can improve the adhesion of mortar to a range of substrates, including concrete, masonry, brick and tiles.
This makes it particularly useful for bonding coats, concrete repairs and renovation work.
Improved workability
A suitable polymer dispersion can make a mortar easier to mix, apply, spread and finish.
For the contractor, this means a mortar system that is easier and more practical to work with.
Improved mechanical properties
A polymer-modified mortar can offer improved resistance to mechanical loads. Depending on the formulation, the addition of polymer can contribute to both compressive and flexural strength.
Reduced water penetration
SBR can improve the resistance of a mortar to water penetration.
This can be beneficial for applications such as:
- cement renders;
- water-resistant mortars;
- concrete repairs;
- applications exposed to moisture.
However, a polymer dispersion does not automatically make a mortar completely waterproof. Final performance depends on the complete mortar formulation, dosage, layer thickness and application.
Improved durability
Improved resistance to water penetration and a suitable polymer structure can contribute to better resistance against certain environmental stresses, including freeze-thaw cycles.
Dosage and concentration
The amount of polymer relative to the amount of binder has an important influence on the properties of the final mortar. The optimum amount of polymer dispersion depends on the application, the desired properties and the mortar formulation.
A dosage that is too low may not provide the desired effect. However, adding more SBR does not automatically result in better performance.
When determining the dosage, it is also important to consider the solids content of the polymer dispersion. A product with a higher solids content contains more solid material at the same volume of liquid product.
Therefore, a dosage expressed in litres alone does not always provide sufficient information about the actual amount of polymer added to the mortar.
SBR in practice
At Reynchemie, we produce the polymer dispersion RC ACRYPLAST, with a solids content of approximately 46%. It has been developed to improve cement-based mortars and concrete and can be used for applications including:
- bonding coats;
- cement renders;
- concrete repairs;
- water-resistant mortars;
- improved cement mortars;
- cement-based joints;
- renovation applications.
Depending on the mortar formulation and application, RC ACRYPLAST may also be suitable for certain lime- and lime-cement-based systems.
Need help with your application?
Unsure about the correct mixing ratio or have a technical question about RC ACRYPLAST? Our advisers will be happy to help.
