| HS Code | 824006 |
| Chemical Composition | Vinyl acetate ethylene copolymer (VAE) |
| Appearance | White free-flowing powder |
| Bulk Density | 400-600 g/L |
| Particle Size | ≥90% through 100 mesh |
| Ph Value | 6.0-8.0 (5% aqueous solution) |
| Ash Content | 10-15% |
| Minimum Film Forming Temperature | 0-5°C |
| Glass Transition Temperature | 0-10°C |
| Redispersibility | Fully redispersible in water |
| Viscosity | 1000-3000 mPa·s (5% solution) |
| Water Resistance | Improved water resistance and wet abrasion resistance |
| Flexibility | Enhances flexibility and crack resistance |
| Adhesion | Excellent adhesion to gypsum and various substrates |
| Compatibility | Compatible with gypsum, cement, and fillers |
As an accredited RDP for Gypsum Self-leveling Compounds factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | RDP for gypsum self-leveling compounds is supplied in 25 kg multi-layer paper bags with moisture-proof inner lining, palletized and shrink-wrapped for safe transport. |
| Container Loading (20′ FCL) | 20′ FCL of RDP powder in palletized, moisture-protected bags, safely loaded for gypsum self-leveling compound production. |
| Shipping | RDP for gypsum self-leveling compounds is shipped in 25 kg moisture-proof lined paper bags, palletized and shrink-wrapped. Transport via standard sea, land, or air freight in dry, ventilated containers. Protect from humidity and direct sunlight. Not classified as dangerous goods under IMDG/ADR regulations. |
| Storage | Store RDP in a cool, dry, shaded, and well-ventilated area. Keep bags sealed and off the ground on pallets to prevent moisture absorption. Avoid exposure to rain, humidity, and direct sunlight. Use within six months of manufacture; reseal opened packaging tightly. Proper storage preserves powder flow and gypsum self-leveling performance. |
| Shelf Life | Shelf life is typically 12 months when stored unopened in a cool, dry place, protected from moisture. |
In residential refurbishment and new-construction floor preparation, redispersible polymer powder based on vinyl acetate–ethylene copolymers is metered into calcium sulfate self-leveling compounds at 1.0–3.0 wt% of the dry mix. The powder is typically spray-dried with a polyvinyl alcohol protective colloid, and its glass transition temperature for gypsum applications commonly falls between -10 °C and +15 °C depending on ethylene comonomer content. During hydration of calcium sulfate hemihydrate to calcium sulfate dihydrate, the polymer particles coalesce around gypsum crystals and form a continuous film that bridges microcracks, reduces surface dusting, and increases adhesion to primed substrates. In resilient floor preparation under LVT, SPC, and engineered wood, the wet compound is mixed at a water-to-binder ratio of 0.22–0.28 using a forced-action mixer or continuous mixing pump and adjusted to a flow ring diameter of 240–260 mm when tested according to EN 12706. RDP does not replace a damp-proof membrane; on subfloors with rising moisture, a separate epoxy or polyolefin barrier remains mandatory. The finished layer must reach the covering manufacturer’s residual moisture threshold before resilient flooring installation, commonly 0.5 CM% for vapor-tight coverings and up to 1.0 CM% for vapor-permeable wood systems in accordance with Fachverband Estrich und Belag guidance. Polymer contents below 1.0 wt% produce insufficient film continuity, while contents above 3.5 wt% frequently increase air entrainment, prolong setting time, and reduce early strength without proportional benefit. The powder is dry-blended in twin-ribbon or ploughshare mixers before bagging, and batch-to-batch variance in calcium sulfate phase composition can shift water demand and flow retention more than the polymer dosage itself.
In featheredge applications where the gypsum compound tapers from 6 mm to 0 mm, drying rate is governed by surface evaporation rather than hydration demand, and polymer film formation competes with rapid water loss into the substrate. RDP dosage in this application is frequently raised to 2.0–3.0 wt% to maintain film continuity at the razor edge, but the higher polymer content introduces a processing conflict: the polyvinyl alcohol colloid raises mix water retention, and when combined with a polycarboxylate ether superplasticizer, the formulation may show reduced flow retention after 10 minutes and require adjustment with a secondary dispersant such as a melamine sulfonate or naphthalene sulfonate condensate. On substrates warmer than 30 °C, the polymer can coalesce prematurely before the gypsum matrix has fully crystallized, producing a weak surface laitance. The primer must therefore be applied in two coats on absorbent calcium sulfate substrates, and compound placement should be avoided on substrate temperatures above 30 °C. Production-scale failure modes include edge craters, pinholing from an incompatible defoamer, and delamination when solvent-based primers partially soften the polymer film. Mechanical properties are improved primarily in flexural strength and adhesion, not in surface hardness, and this trade-off must be accounted for when the featheredge receives a rigid polyurethane or epoxy coating.
Hydronic radiant heating installations impose thermal cycling on calcium sulfate self-leveling compounds, and the polymer film functions as a stress-relief phase in the crystalline gypsum matrix. RDP is specified at 1.5–2.5 wt% in this segment because the polymer improves strain tolerance under cyclic expansion and contraction without substantially reducing thermal conductivity. Commissioning of heated screeds must follow EN 1264-4, and heating circuits are not activated before the gypsum layer has reached the specified residual moisture. The cured polymer film is water-insoluble but remains moisture-sensitive under prolonged wetting, so permanent wet areas fall outside the operational boundary. On site, the powder is mixed with cooled water and pumped through a screw-type continuous mixer; rotor speeds above 300 rpm can entrain air if the defoamer is not matched to the protective colloid. Covering cycles are constrained by residual moisture readings under the commissioning protocol and by floor covering manufacturer limits, and RDP modification does not permit shortening the minimum drying period before heat-up. The final covering is typically LVT, engineered wood, or ceramic tile over a heated calcium sulfate screed whose polymer content has been balanced to avoid surface elasticity that would reduce tile adhesive shear transfer.
Renovation over old ceramic tile and mechanically prepared concrete places tensile adhesion at the foreground, and RDP dosages between 2.0–3.0 wt% are selected because the polymer contributes to bond strength on non-porous tile surfaces after mechanical roughening. The surface is cleaned and primed with a solvent-free acrylic or epoxy primer; omission of priming on highly absorptive gypsum or anhydrite substrates causes rapid water extraction and a granular, low-cohesion interface. Adhesion is measured by EN 13892-8 pull-off testing, and specifying a minimum of 1.0 MPa is common for renovation systems over glazed tile. On old concrete, cementitious contamination must be neutralized because calcium sulfate systems are incompatible with free lime and Portland cement residues due to ettringite formation at the interface. Shot blasting or diamond grinding to ICRI CSP 2–3 is the accepted preparation method, and the prepared surface must be vacuumed to remove fines before priming. The polymer film accommodates minor substrate movement, but it does not equalize severe deflections or compensate for an unstable base. The finished compound serves as a smooth substrate for ceramic tile, LVT, or epoxy coatings, and its elevated polymer content reduces the risk of edge spalling in renovation traffic conditions.
Under heavy-duty polyurethane, epoxy, and methyl methacrylate floor coatings, the self-leveling compound must provide surface cohesion and resist moisture-driven delamination. RDP is used at 1.0–2.0 wt% because higher polymer contents can produce a slightly elastic surface that reduces the pull-off adhesion of rigid epoxy coatings. The compound is poured at 3–12 mm thickness and cured to 0.5 CM% residual moisture before coating. In-situ relative humidity in the gypsum substrate is measured with ASTM F2170 probes, and surface moisture emission is measured with ASTM F1869 calcium chloride test when specified. Polymer modification does not eliminate these measurements. The polymer film is organic and may be sensitive to aggressive solvents in certain epoxy primers; a solvent-free epoxy primer is preferred to prevent interface softening. Diamond sanding after cure removes laitance and exposes a compact surface for coating. In production-scale failure observations, pinholes occur when the defoamer is overdosed or when the mixing pump entrains air at high speed. The cured composite must achieve the specified EN 13813 strength class, and polymer dosage must be reduced if compressive strength falls below the design class for the imposed traffic category. No forward adjustment of coating adhesion can substitute for insufficient residual moisture control in this application.
Machine hall floor repair compounds are formulated with alpha hemihydrate-based calcium sulfate binders and redispersible polymer powder at the lower end of the normal working range, typically 1.0–1.5 wt%, to preserve compressive strength while improving flexural performance and bond. The polymer phase has lower stiffness than the gypsum crystalline matrix, and increasing RDP from 1.5 wt% to 3.0 wt% generally reduces compressive strength and increases air content. Processing with a low-speed planetary mixer followed by pouring through a spiked roller removes entrained air and produces a dense surface. The cured compound can meet EN 13813 classes such as C30-F7, provided binder quality and water demand are strictly controlled. This application rejects wet-mixing shortcuts: direct addition of the powder to the full water charge without pre-mixing can create undispersed polymer agglomerates that appear as surface craters after setting. The finished layer is used as an industrial substrate under heavy wheeled traffic, but it is not formulated for constant water immersion or for exterior exposure. The practical upper limit for polymer content in load-bearing industrial levelling compounds is dictated by this strength-air trade-off rather than by bond performance.
Indoor air quality certification has become a downstream requirement in residential and commercial flooring projects, and RDP selections for gypsum self-leveling compounds are now constrained by emission standards as well as mechanical performance. Powders formulated with low residual vinyl acetate monomer and low volatile organic compounds can support EMICODE EC1 Plus, AgBB, and French VOC class A+ compliance when tested under chamber conditions according to ISO 16000-3 and ISO 16000-6. The polyvinyl alcohol protective colloid and any residual surfactant must be controlled because these components can contribute to short-term aldehyde emissions under specific thermal storage conditions. In heated floor systems, emission testing is conducted at an elevated chamber temperature to reflect service conditions, and RDP selection may shift toward copolymers with lower heat release under the devolatilization profile. The final application benefit is not a mechanical improvement but a regulatory one: the formulated gypsum underlayment can be specified in LEED v4 and BREEAM indoor environment schemes where low-emitting floor materials are required. Nevertheless, emission compliance is formulation-specific rather than polymer-specific, and a powder that passes in one cementitious system cannot be assumed to pass in a calcium sulfate self-leveling compound without re-testing.
| Application segment | Primary specification | Test method | Controlled property |
|---|---|---|---|
| Resilient underlayment | EN 13813 | EN 13892-2 | Flexural and compressive strength class |
| Bond to ceramic tile and concrete | EN 13813 | EN 13892-8 | Tensile adhesion strength |
| Heated screeds | EN 1264-4 | EN 1264-4 | Commissioning and pipe cover requirements |
| Moisture before coating | ASTM F2170 | ASTM F2170 | In-situ relative humidity |
| Surface moisture emission | ASTM F1869 | ASTM F1869 | Moisture vapor emission rate |
| Flow consistency | EN 12706 | EN 12706 | Flow ring diameter |
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Product RDP-GSL 501 is a vinyl acetate–ethylene (VAE) redispersible polymer powder specified for gypsum-based self-leveling compounds. The grade is a silane-functional VAE powder with a nominal glass transition temperature of −5 °C to +5 °C determined by differential scanning calorimetry in accordance with ISO 11357-2. It is supplied as a free-flowing powder with bulk density of 450–550 g/L (DIN EN ISO 60), residual moisture below 1.5 wt% after 1 h at 105 °C (ISO 787-2), ash content of 10–14 wt% after combustion at 1000 °C, and residue on a 315 µm sieve not exceeding 2.0 wt%. The powder redisperses in water to a 50% solids dispersion with pH 6.5–8.5 and Brookfield LV viscosity of 800–2,500 mPa·s at 20 °C using spindle 3 at 30 rpm. Minimum film-forming temperature is 0–4 °C (ISO 2115), allowing film coalescence without added coalescing solvents at substrate temperatures above 10 °C. The product is used at addition rates of 1.5–4.0 wt% based on total dry gypsum binder, with 2.0–3.0 wt% representing the usual balance between strength retention and surface adhesion in self-leveling underlayments.
| Parameter | Test method | Representative limit or range |
|---|---|---|
| Bulk density | DIN EN ISO 60 | 450–550 g/L |
| Dry sieve residue on 315 µm | ISO 8130-10 | ≤ 2.0 wt% |
| Residual moisture | ISO 787-2 | ≤ 1.5 wt% |
| Ash content after 1000 °C | ISO 3451-1, Method A | 10–14 wt% |
| pH of 50% redispersion | ISO 976 | 6.5–8.5 |
| Minimum film-forming temperature | ISO 2115 | 0–4 °C |
| Glass transition temperature | ISO 11357-2 | −5 °C to +5 °C |
| Viscosity of 50% solids redispersion | ISO 1652 | 800–2,500 mPa·s at 20 °C |
The values are representative quality-control limits for the VAE/silane class. Lot-specific certificates may show narrower ranges, particularly for moisture and bulk density after transportation to humid storage locations.
During mixing, calcium sulfate hemihydrate dissolves and begins to nucleate gypsum dihydrate while the redispersible powder must re-form a latex within the first 60–120 s of wet mixing. This parallel process creates a competitive water demand that is not present in cementitious self-leveling compounds. Gypsum-based self-leveling formulations typically operate at water-to-powder ratios of 0.20–0.28, and the addition of RDP increases water demand through the polyvinyl alcohol protective colloid. To maintain a flow-ring spread of 145–155 mm measured by EN 12706, polycarboxylate ether superplasticizer dosage is commonly raised from 0.08 wt% to 0.15 wt% when RDP-GSL 501 is introduced at 2.5 wt%. Without this adjustment, the initial spread may remain acceptable but flow retention at 10 min can fall from 155 mm to approximately 125 mm, leaving insufficient open time for large-floor pump applications.
Air entrainment is a further processing variable. The protective colloid and the spray-dried powder structure stabilize fine air bubbles during high-shear mixing. At addition rates above 3.0 wt%, air content in the fresh mortar can exceed 6 vol% unless a polyether siloxane defoamer is added at 0.10–0.25 wt% of dry compound. Hardened air content should remain below 3.5 vol% when tested according to EN 1015-7, because higher levels reduce compressive strength by more than 15% relative to a low-air reference mix. Production-scale batch mixers of 500–2,000 L working volume require total blend times of 180–240 s at paddle tip speeds of 1.5–2.5 m/s to disperse RDP without destroying lightweight fillers. Powder temperature should remain below 45 °C; higher frictional heating can soften the polyvinyl alcohol shell and cause agglomeration on 80–125 µm safety screens.
Field experience from continuous dry-mix lines indicates that bulk density batch-to-batch variance remains below ±5% when the anti-caking agent feed is held constant. Lot-to-lot variability in moisture content becomes significant above 60% relative humidity. Partially opened bags should be consumed within 7 days, because moisture uptake above 1.5 wt% accelerates blocking in storage silos and reduces redispersibility. Unopened bags stored at 5–35 °C and below 60% relative humidity retain specification compliance for 6 months.
A gypsum-specific RDP is differentiated less by polymer composition than by protective colloid selection, anti-caking system, and compatibility with sulfate-rich pore water. RDP-GSL 501 is a VAE/silane grade with comparatively low minimum film-forming temperature and moderate water demand. Tile-adhesive grades often use higher ethylene content to reduce glass transition temperature and improve deformation, but they may carry higher defoamer demand or residual surfactants that generate excessive foam in low-viscosity gypsum slurries. EIFS-type RDP powders are frequently formulated for cementitious substrates with higher alkalinity and may have minimum film-forming temperatures above 10 °C, which is not suitable for fast-drying gypsum compounds applied at 10–15 °C slab temperature.
Styrene-acrylate RDP grades offer greater water resistance after film formation, but their compatibility with gypsum self-leveling compounds is less predictable. In sulfate-rich aqueous phase, styrene-acrylate dispersions can exhibit higher viscosity drift and lower early adhesion to damp concrete unless a compatible polyvinyl alcohol protective colloid is used. Published comparative data for gypsum-specific RDP grades under production conditions are limited; however, plant-level testing of a C25-F6 gypsum self-leveling compound according to EN 13813:2002 shows that RDP-GSL 501 at 2.5 wt% retains a 28-day flexural strength of 6.0–7.0 N/mm² and compressive strength of 25–28 N/mm², whereas an equivalent styrene-acrylate powder may reduce compressive strength by 2–4 N/mm² at the same flow class due to higher air content.
| Comparative parameter | RDP-GSL 501, VAE/silane | Styrene-acrylate RDP | Liquid VAE latex |
|---|---|---|---|
| Delivery form | Dry powder, 450–550 g/L | Dry powder | Aqueous dispersion, 50–55% solids |
| Minimum film-forming temperature | 0–4 °C | 10–20 °C | 0–5 °C |
| Storage stability below 0 °C | Stable in unopened bags | Stable in unopened bags | Freeze-sensitive |
| Water demand in gypsum SL compound | Moderate; requires PCE adjustment | Moderate to high | High if added as liquid latex without reformulation |
| Early pull-off adhesion to concrete after 7 days | 0.8–1.2 N/mm² | 0.5–0.9 N/mm² | 0.7–1.1 N/mm² |
| Field batching risk | Low; dry-mix controlled | Low; dry-mix controlled | High; two-component metering error |
Liquid latex is not a direct alternative for dry-mix production. A latex with 50–55% solids cannot be introduced into a dry blend without causing premature agglomeration, and it introduces freeze-thaw instability if stored on unheated job sites. The dry RDP maintains open time and film formation without adding solvent or coalescing agent, and it allows one-component packaging in 25 kg bags. The principal difference from polycarboxylate superplasticizers is functional: superplasticizers modify particle dispersion and water demand, while RDP forms a coalesced polymer network between gypsum crystals and at the substrate interface after drying.
Continuous mixing and pumping equipment used for gypsum self-leveling compounds imposes stricter requirements on powder dispersion than batch mixing. RDP-GSL 501 is designed to redisperse under high-shear continuous mixers operating at 600–1,000 rpm for 60–120 s. Low-speed paddle mixing below 300 rpm may leave undispersed polymer agglomerates visible as surface specks on the hardened screed. Water metering accuracy is critical; continuous pump units must hold water flow tolerance within ±1% of setpoint to avoid viscosity drift. With a water-to-powder ratio of 0.24, the fresh mortar should reach a pumpable flow-ring spread of 150–155 mm without segregation.
In a C25-F6 formulation according to EN 13813:2002, addition of 2.5 wt% RDP-GSL 501 typically increases pull-off adhesion to a prepared concrete substrate from 0.4–0.6 N/mm² to 0.8–1.2 N/mm² when tested after 7 days at 23 °C and 50% relative humidity using ISO 4624. The same dosage reduces surface dusting and improves the sanding resistance of gypsum underlayments before floor-covering installation. The polymer phase does not prevent the normal dimensional change of gypsum but limits crack propagation at installed thicknesses from 3 mm to 10 mm when the substrate has been primed and isolated from excessive moisture.
Operational boundaries apply. RDP-GSL 501 should not be dry-blended with high free-lime binders or stored in silos previously containing cementitious accelerators at pH above 12, because alkaline hydrolysis can destabilize the protective colloid. It should not be used at dosages below 1.0 wt%, because film formation is insufficient to produce measurable adhesion gain. Dosages above 5.0 wt% can retard strength development and produce tacky surfaces under low-ventilation conditions. Published data for gypsum self-leveling compounds with this specific silane-functional grade are limited to formulation-specific application testing; projects outside the stated water ratio and temperature range require pre-qualification by laboratory trial mix.
