RDP Dosage in Dry Mix Mortar

What is RDP in Construction?

Re-Dispersible Polymer Powder (RDP) is a key additive in construction materials, particularly in dry mix mortar. It enhances adhesion, flexibility, and durability, making it essential for applications such as tile adhesives, self-leveling compounds, and wall putty.

RDP improves workability, crack resistance, and overall mechanical properties, ensuring high-performance mortar formulations.

RDP Polymer Powder Composition

RDP is primarily composed of:

Base Polymer: Often vinyl acetate-ethylene (VAE) or acrylic-based polymers.

Additives: Anti-caking agents, stabilizers, and plasticizers to enhance stability and performance.

Protective Colloids: Typically polyvinyl alcohol (PVA), which helps with dispersion in water.

When mixed with water, RDP re-disperses to form a stable polymer emulsion, improving mortar adhesion to various substrates.

RDP Chemical Properties

Key chemical properties of RDP include:

Particle Size: Typically ranges from 0.1 to 2 µm, ensuring easy dispersion.

Glass Transition Temperature (Tg): Affects flexibility and adhesion properties.

Ash Content: Influences the final strength and setting time of mortar.

Moisture Resistance: Helps prevent cracking and water damage.

Understanding these properties helps in selecting the right RDP for specific dry mix mortar applications.

RDP Dosage in Dry Mix Mortar

The optimal dosage of RDP varies depending on the mortar type and application:

Application

RDP Dosage (% of Cement Weight)

Tile Adhesive 2% – 5%

Skim Coat/Wall Putty 1% – 4%

Self-Leveling Mortar 1% – 3%

Waterproof Mortar 3% – 6%

Repair Mortar 2% – 5%

Using the right dosage ensures optimal performance, balancing adhesion, flexibility, and durability. Overuse may lead to excessive costs and extended setting times, while underuse can compromise strength and adhesion.

Conclusion

Selecting the correct RDP dosage in dry mix mortar is essential for achieving the best results in construction applications. Understanding RDP polymer powder composition and chemical properties helps in making informed decisions for high-performance mortar formulations.

For more details on choosing the right RDP for your project, contact us today!

Application

Hydroxyethyl cellulose（HEC）

The most important property of hydroxyethyl cellulose powder is that it acts as a thickener, in creasing the viscosity of the liquid,and its thickening depends on its concentration. If you're searching for a versatile solution that enhances the performance of your products, look no further than Hydroxyethyl Cellulose (HEC) powder.

Gypsum Special Grade HPMC

The gypsum special grade hydroxypropyl methyl cellulose HPMC has the characteristics of high water retention, dispersibility, good fineness, good workability and easy dissolution. widely used in gypsum products like gypsum plaster, adhesive plaster, embedded gypsum, tile adhesives etc.

Daily Chemical Products Additive

Daily Chemical HPMC has a variety of properties such as thickening, foam stabllization,emulifiation, and easy dispersion. Shampoo Additive HPMC has good compatibility with various additives of other daily chemical products. It is widely used in detergents, shower gels, shampoos, hand sanitizers, and laundry liquid and other products.

Tile Adhesive Additive

Tile Adhesive Additive HPMC can ensure the smooth construction on difterent base surtaces, even when the ambient temperalure is relalively harsh, the tile adhesive can be given a long enough open time and adjustable time.

Gypsum Additive

In gypsum products, the focus is on water retention, retardation and lubrication. Different gypsum has different effects on product performance, so thickening, water retention, and retardation determine the quality of gypsum building materials.

Mortar Additive

Adding hydroxypropyl metylellulose can improve anti-sip performance, improve wetting performance, thicken, improve batch scraping and slipping, easy to level, improve surface performance and strength, and have very good compatibility with other additives.

Putty Powder Additive

Hydroxypropyl metylcellulose is a commonly used raw material in powdered building materials, which greatly improves the slip performance and anti-sag performance of the construction, improves the wettability, improves the anti-slip performance of the putty, improves the leveling effect of the putty, and improves the construction eficlency.

Technical Guidelines for Hydroxypropyl Methylcellulose (HPMC)

As a professional manufacturer of architectural-grade HPMC, we provide you with comprehensive technical guidance and problem-solving support throughout the production and application processes.

How much do you know about Hydroxypropyl methyl cellulose(HPMC)?

Hydroxypropyl methyl cellulose (HPMC) is a non-ionic cellulose ether obtained by cellulose alkalization, etherification, neutralization and washing. HPMC has good thickening, dispersing, emulsifying, film-forming properties, etc.It is the first choice for production of high quality building materials additives.

Laboratory overview

We have both Chemical Lab and Application Lab to ensure each order's best satisfaction

How to improve the adhesion of putty

When encountering the projects that have been constructed, it is found that the adhesion of putty on the exterior wall is poor, the following methods can be adopted to improve the adhesion of putty:

Dissolution Method

Take the required amount of hot water into the container and heat to above 85., stir slowly and add the product gradually The cellulose initially floats on the water, but gradually disperses in water and forms homogeneous slurry. Goon stirring until it cools down and becomes clear

Products

Faq

Why does hydroxypropyl methylcellulose (HPMC) have an odor?

HPMC is widely used in industries such as construction materials, coatings, synthetic resins, ceramics, pharmaceuticals, food, textiles, agriculture, cosmetics, and tobacco. HPMC can be classified into architectural grade, food grade, and pharmaceutical grade based on its application. Currently, most domestically produced HPMC falls under the architectural grade category. In the architectural grade, a large amount of HPMC is used in putty powder, accounting for approximately 90% of its usage, while the rest is used in cement mortar and adhesives.

Regarding the relationship between viscosity and temperature in HPMC (HPMC viscosity), what should be noted in practical applications?

The viscosity of HPMC is inversely proportional to temperature, meaning that viscosity increases as temperature decreases. When we refer to the viscosity of a certain product, it generally refers to the measurement result of its 2% water solution at 20 degrees Celsius. In practical applications, in regions with large temperature differences between summer and winter, it is advisable to use relatively lower viscosity during winter for better construction. Otherwise, at low temperatures, the viscosity of the cellulose increases, resulting in a heavier feel during application. Medium viscosity: 75,000-100,000 (mainly used for putty) Reason: Good water retention. High viscosity: 150,000-200,000 (mainly used for polystyrene particle insulation mortar powder and foamed glass bead insulation mortar) Reason: High viscosity, reduces mortar dusting and sagging, improves construction. However, in general, higher viscosity provides better water retention. Therefore, many dry mortar manufacturers consider using medium-viscosity cellulose (75,000-100,000) instead of low-viscosity cellulose (20,000-40,000) to reduce the dosage and costs.

What is the relationship between the gelation temperature of hydroxypropyl methylcellulose (HPMC) and something else?

In the application of HPMC in putty powder, it plays three roles: thickening, water retention, and facilitating construction. Thickening: Cellulose can thicken the mixture, maintain uniform suspension, and prevent sagging. Water retention: It slows down the drying process of putty powder and assists in the reaction of lime and calcium in water. Construction: Cellulose acts as a lubricant, improving the workability of the putty powder. HPMC does not participate in any chemical reactions; it only serves as an auxiliary agent. When putty powder is mixed with water and applied to the wall, a chemical reaction occurs because new substances are formed. However, if the putty powder is scraped off the wall, ground into powder, and reused, it is not suitable because a new substance (calcium carbonate) has already formed. The main components of lime and calcium powder are Ca(OH)2, CaO, and a small amount of CaCO3. The reaction can be represented as: CaO + H2O = Ca(OH)2 — Ca(OH)2 + CO2 = CaCO3 ↓ + H2O. Under the action of water and carbon dioxide in the air, lime and calcium carbonate are formed. HPMC only assists in water retention and the better reaction of lime and calcium; it does not participate in any reactions itself.

How to choose the appropriate hydroxypropyl methylcellulose (HPMC) for different applications?

The gelation temperature of HPMC is related to its methoxy content. The lower the methoxy content, the higher the gelation temperature.

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