Choosing the Right Redispersible Polymer Powder

Choosing the Right Redispersible Polymer Powder for Mortar

Redispersible Polymer Powder (RDP) in mortar is a crucial component for strong, reliable building structures. It is especially useful to enhance the original characteristics of constructions materials, such as tile adhesives, mortars, and other cement-based compounds.

RDP is mixed with water, so its particles get redispersed to form a polymer emulsion. This redispersed emulsion retains the properties of the original RDP compound and offers a wide range of benefits.

However, choosing the right redispersible polymer powder is extremely important. This will ensure that the original properties of the mortar mix get enhanced and achieve best results.

Choosing the Right Redispersible Polymer Powder

Redispersible Polymer Powder (RDP) is essentially a re-disseminating polymer-based emulsion that is derived from the spray-drying of a copolymer emulsion. The spray-drying process converts the fluid emulsion into a fine free-flowing powder.

However, the RDP powder quickly returns to its original emulsion state when mixed with water in the proper ratio. The emulsified compound retains all its original properties and provides the same to the construction mixture.

Some of the key reasons for choosing RDP is its ability to enhance the mortar’s rheological properties. It can improve the fluidity of the mortar mix, so it flows and spreads evenly. This makes it easier to apply the mortar and get a smoother final finish.

Another key characteristic RDP enhances is the water resistance of the mortar mix. By adding RDP, it is possible to reduce the damaging effects of water on tile adhesives. This helps build a stronger, and more durable structure.

Besides this, you should choose RDP to improve the mortar’s bonding strength. This lowers the risk of untimely detachment and ensures that the tiles adhere to the substrate surfaces for a longer time.

Assessing Flexibility and Rigidity of Polymer Powder

It is crucial to determine the inherent properties of polymer powder for use with mortar before buying it. Let’s check out the simple way to assess flexibility and rigidity of polymer powder –


Elasticity is one of the most crucial characteristics to check if you want to choose the right redispersible polymer powder. A good quality RDP gives incredible elasticity to the mortar mix. This allows the mortar to withstand structural movement safely. It also prevents the mortar from developing cracks on the surface.

Rigid RDP products do not have sufficient elasticity. This often decreases the flexibility of the mortar and makes it prone to cracks. Elasticity is a critical characteristic when choosing RDP, as it helps to measure the level of flexibility it will provide to the mortar on drying.

Here’s how to quickly check the elasticity of an RDP product –

  • Tackiness – An elastic redispersible polymer powder will show some level of tackiness to the touch. However, a rigid polymer powder will feel dry and lack noticeable level of tackiness.
  • Stretchability – An elastic polymer powder is easy to stretch. This shows its ability to bear movement without cracking. You can check the stretchability of a redispersible polymer compound by gently stretching or pulling the emulsion. The limit of its ability to elongate before it breaks will show its stretchability level.
  • Recovery – You can check the recovery capability of the RDP emulsion by seeing how well it returns to its original state. An elastic polymer product shows good recovery and turns back to its original form quite quickly. In contrast, a rigid polymer powder has limited flexibility and does not retain its original shape completely.

Tensile Strength

When you choose RDP which is flexible it will have a lower tensile strength. This helps the mortar to adapt to small deformations which may prevent cracks from developing. However, an inflexible RDP tends to have a greater tensile strength. This ensures that the mortar is more resistant to deformations.

Tensile strength is an important characteristic to consider when choosing RDP. You should check the rigidity or flexibility of the redispersible polymer powder you need to use with the mortar.

Here’s a quick method of assess the tensile strength of an RDP for use with mortar –

  • Preparation – First, you will need to prepare a test sample by mixing the RDP with water, as per the manufacturer’s instructions. Let the mixture to settle, dry and get solidified.
  • Testing – Get a tensile strength testing machine that applies force on the sample till it breaks.

A flexible polymer powder will show lower tensile strength, which can deform the mortar under stress. On the other hand, rigid polymer powder will show higher tensile strength, indicating its ability to resist deformation strongly.

Film Formation

A highly quality flexible redispersible polymer powder forms a thin, elastic film while rigid RDP forms a thicker, and more rigid film on the mortar surface. The elasticity of these films determines the overall rigidity or flexibility of the mortar produced. Thus, the appearance of the film formed by RDP is a great way to check the level of flexibility or rigidity that the mortar will have.

Here are two main characteristics to check when assessing film formation of RDP with mortar –

  • Thickness – Flexible RDP form a thin film that can deform slightly without developing cracks. In contrast, a rigid RDP will create a thicker and less elastic film on the mortar surface. You can simply compare the thickness of the films formed by two RDP products to evaluate their flexibility.
  • Appearance – Flexible RDP products tend to form a film which is pliable and smooth in appearance. It does not display any visible signs of brittleness or stiffness. On the other hand, rigid polymer powder usually creates a brittle or rough-looking film on the mortar surface upon drying.

It is very important to check the rigidity or flexibility of the product for choosing the right redispersible polymer powder. By checking the elasticity, tensile strength and film-forming properties you get valuable information and can decide the best RDP for your requirement.

However, you need to remember that the rigidity or flexibility of the polymer powder will determine the performance and durability of the mortar mix.

Factors to Consider when Choosing Redispersible Polymer Powder

Now we know the importance of checking flexibility and rigidity for choosing the right redispersible polymer powder. Let’s check the important factors to consider when choosing RDP for use with mortar –

Performance Requirements

The first factor to choose RDP is to know your exact performance requirements. For instance, you have a choice between different “grades” of RDP, which essentially determine its quality. Hence, the specific requirements of your project will determine the grade of RDP most suited for your project.

If you need to enhance the water-resistant properties of the mortar, you should choose RDP that has a higher hydrophobic capability. The quality and grade of RDP can also be determined by its polymer composition. Besides this, when choosing RDP make sure to buy the one with the highest solid content, as it directly affects its bonding strength and durability.


As mentioned above, redispersible polymer powder is made in different grades, depending on their exact intended application. For instance, you can choose RDP especially made for use with tile adhesives, or self-leveling compounds, or external rendering. Hence, you should consider the specific needs of the project to choose the right redispersible polymer powder. This way, you can ensure that the RDP is most effective for its intended use.


Make sure that the RDP you choose is compatible with the other components of the mortar mix, such as chemical admixtures, aggregates, and cement. Incompatibility between RDP and other construction compounds may cause problems, such as sub-par performance. Lack of compatibility between the RDP and other construction compounds can even lead to the failure of the mortar.

For instance, if there is incompatibility between the RDP and other construction chemicals, it can cause poor dispersion, decrease overall quality, and reduce performance too.


Performance is one of the most important factors to keep in mind when choosing the right redispersible polymer powder. You should assess the performance characteristics of various RDP products, such as their water resistance, workability, impact resistance and adhesion power.

Choose RDP that will enhance the required characteristics in your mortar mix.


Always choose redispersible polymer powder for mortar that increases the workability or functions of your mortar. It should be easy to mix, spread and effortless to apply. A good workability in RDP lets you have better control and ensures optimal application.

Water Resistance

The RDP you choose should have excellent water resistance. Mortar surfaces, especially those on the exterior of buildings are subject to harsh weather conditions, such as rain. With maximum water resistance, the RDP-mixed mortar will not degrade, develop cracks, and suffer other water-related damage.


The adhesive property of RDP is another important factor to consider when choosing the most suitable redispersible polymer powder for mortar. Ideally, an RDP should enhance the bonding power between the mortar and substrate, irrespective of the materials. For instance, an ideal RDP should be able to form a strong bond between concrete, wood, and tiles, which ensure long-lasting adhesion.

Impact Resistance

Higher impact resistance is desired in mortar which is meant for use in areas prone to mechanical stress and impact. Choosing RDP with good impact resistance provides extra durability and protects the building surface against damage.

Glass Transition Temperature

Amorphous polymer products generally have three mechanical states – viscous, elastic, and glassy.

When RDP is at a low temperature, it becomes a rigid solid, just like glass. In this state, the RDP allows very small deformation if it suffers an impact, hence it is called the glassy state.

As temperatures rise higher, the material shows increasing deformation. However, this deformation is comparatively stable within a certain range of temperatures. During this stage, the RDP is in an elastic state.

At higher temperatures, the RDP gets gradually more deformed and eventually turns to a viscous liquid. During this stage, the deformation cannot be corrected, hence the stage is called viscous fluid state.

Normally, the state between glassy and elastic state is known as “glass transition”. The corresponding temperature is called “glass transition temperature” or “Tg” in short. An RDP with a glass transition temperature over 0 degree has strong adhesive properties, however its flexibility is not much. When the glass transition temperature is below 0 degrees, the RDP has good flexibility but less adhesion in comparison.

The lowest glass transition temperature for an RDP product should be -15 degrees Celsius while the highest temperature is 5 degrees Celsius. The RDP products from reputed brands in India, such as Sakshi Chem Sciences Pvt Ltd, usually have a glass transition temperature of 3 degrees Celsius.

So, if you want to create an adhesive mortar mix, make sure to choose RDP with strong adhesion. In contrast, you should choose RDP with good flexibility in the mortar for plastering.

Manufacturer Reputation

The reputation and clientele of the RDP manufacturer is also an important factor to consider before buying redispersible polymer powder for mortar. It is advisable to choose a brand which is well-established and reliable, with a proven track record of satisfied customers.

The brand of choice should supply high-quality redispersible polymer powder products. For assessing this, you can check the technical support, product certifications, testing methods, and customer testimonials. Make sure these aspects of the RDP manufacturer meet the international quality standards for construction chemicals and building additives.

Cost Considerations

Last, but not least, the cost of RDP is also an important factor to consider before buying redispersible polymer powder. Make sure that the cost of the RDP is affordable, but also the product should be good quality.


Choosing the right redispersible polymer powder is extremely crucial to ensure strong and long-lasting structures. There are several factors to consider before buying the best-suited RDP product.

For instance, the RDP you choose should have strong bonding strength, easy application abilities, and suit your specific construction requirements. Make sure to check the flexibility, or rigidity, as well as the overall quality of the redispersible polymer powder product. Reputed brands, such as Sakshi Chem Sciences Pvt. Ltd. have been manufacturing and RDP supplier for decades.