| HS Code | 218096 |
| Product Name | RDP for Cementitious Underlayment Self-leveling |
| Chemical Base | Vinyl Acetate-Ethylene (VAE) Copolymer |
| Appearance | White or Off-White Free-Flowing Powder |
| Bulk Density | 400-600 g/L |
| Particle Size | ≤10% Residue on 400 μm Sieve |
| Moisture Content | ≤1.0% |
| Ash Content | 10-15% |
| Ph Value | 6.0-8.0 |
| Minimum Film Formation Temperature | 0-5°C |
| Redispersibility | Excellent in Water |
| Tensile Adhesion Strength | Enhanced Bonding to Substrates |
| Flexural Strength | Improved Flexibility and Crack Resistance |
| Abrasion Resistance | High Wear Resistance |
| Fluidity | Improves Self-Leveling and Flow Characteristics |
As an accredited RDP for Cementitious Underlayment Self-leveling factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | RDP for cementitious self-leveling underlayment is packaged in 25 kg moisture-proof multi-wall paper bags with PE liner for safe handling. |
| Container Loading (20′ FCL) | 20′ FCL loading: RDP powder in 25 kg bags on shrink-wrapped pallets, safely containerized for self-leveling cementitious underlayment production. |
| Shipping | When shipping RDP for cementitious underlayment self-leveling, use 25 kg moisture-proof bags on sealed, shrink-wrapped pallets. Protect from water, humidity, and punctures during transit. Store in cool, dry, ventilated areas. Handle gently to prevent bag damage, and ensure proper labeling as non-hazardous chemical construction powder. |
| Storage | Store RDP (redispersible polymer powder) in a cool, dry, well-ventilated area. Keep original bags tightly sealed, protected from moisture, rain, and direct sunlight. Avoid stacking on damp floors; use pallets. Shelf life is typically 12 months from production if unopened. Once opened, reseal promptly and use within a short period to prevent caking or degradation. |
| Shelf Life | Store dry, cool, and sealed; avoid moisture. Shelf life is 12 months from date of manufacture. |
On glazed porcelain tile surfaces carrying residual cementitious adhesive films from previous installations, the redispersible polymer powder (RDP) must transfer tensile stress across a non-porous interface while compensating for differential shrinkage between the old tile substrate and a calcium aluminate cement/Portland cement-blended underlayment. At an addition rate of 2.5–4.5 wt% of total dry mix, a vinyl acetate–ethylene (VAE) copolymer with a glass transition temperature below 15°C and minimum film-forming temperature below 4°C is introduced during dry-mix production in a twin-shaft mixer with a usable batch size of 1,500–2,000 kg and a mixing time of 120–180 s. The polymer powder is dry-blended with CEM I 42.5 R, calcium aluminate cement, 0.1–0.3 mm silica sand, limestone filler, calcium sulfate, polycarboxylate ether superplasticizer, defoamer, and low-viscosity cellulose ether. The RDP is metered after the mineral components to avoid shear heating above 50°C in the mixer. On site, the dry compound is mixed with water to a ring flow of 220–260 mm under EN 12706:1999, then applied over a prepared tile surface that has been diamond-ground or mechanically scarified and primed with an aqueous acrylic dispersion. A spiked roller and gauge rake release entrapped air and control the nominal thickness from 2 mm to 10 mm. The cured underlayment reaches compressive strength of 20–25 MPa at 28 d under ASTM C109/C109M-21 and flexural strength of 6 MPa, meeting EN 13813:2002 class CT-C20-F6. Pull-off adhesion measured under ASTM C1583-20 typically exceeds 0.7 MPa, with cohesive failure in the polymer-cementitious overlay rather than adhesive failure at the tile interface. End product types are renovation smoothing compounds for ceramic-tiled floors receiving luxury vinyl tile, rigid core planks, sheet vinyl, and laminate flooring.
RDP addition above 3.5 wt% in fast-track cementitious self-leveling compounds increases plastic viscosity and shortens flow retention, particularly when site water temperature exceeds 25°C or when the dry blend carries high calcium aluminate cement fractions for early strength development. The formulation is therefore maintained between 1.5–3.0 wt% RDP, based on a low-viscosity VAE grade, while a polycarboxylate ether superplasticizer is adjusted to sustain a ring flow of 240–280 mm under EN 12706:1999 after 30 min open time. In production-scale continuous mixers of the worm-pump type, such as m-tec duo-mix and Putzmeister MP 25, the dry blend is conveyed from a 25–50 L/min mixing chamber to the floor through a 10–20 m hose. Air entrainment is kept below 2.0% by defoamer dosage because surface pinholing impairs installation of thin vinyl tiles. A production-scale failure mode observed in continuous pumping is slug flow when poorly dispersed RDP accumulates in the mixing zone; this is controlled by pre-blending RDP with limestone before it enters the blending screw. The fresh mortar is poured onto the substrate and finished with a smoothing bar and spiked roller. Hardened mortar conforms to ASTM C1708/C1708M-19 and EN 13813:2002 class CT-C25-F6, with early compressive strength of 5–8 MPa at 4 h and 25–30 MPa at 28 d. End product types are large-area pump-applied self-leveling underlayments for retail floors, office towers, and corridor renovation before carpet tile, vinyl sheet, and rubber flooring.
Below 40°C operating water temperature in hydronic heating elements cast within a cementitious underlayment, cyclic thermal strain imposes high-cycle fatigue on the polymer-cement matrix even though stress amplitudes remain below the static flexural capacity. The selected RDP is a vinyl acetate–ethylene/vinyl chloride terpolymer at 3.0–5.0 wt% of total dry mortar; the vinyl chloride fraction reduces water uptake, while the ethylene fraction lowers secant modulus and raises elongation at break of the coalesced polymer film. The cementitious blend comprises CEM I 42.5 R, calcium aluminate cement, anhydrite, fine quartz sand 0.1–0.3 mm, and calcium sulfate for controlled ettringite formation. The reduced modulus limits crack formation when the screed temperature cycles from 15°C to 40°C at pipe spacing up to 300 mm. Application is by continuous mixing pump over hydronic pipe arrays fixed to the substrate, with a minimum cover above pipes of 15 mm. The material is finished with a spike roller to remove air and to consolidate the layer around heating elements. Compliance is established through EN 1264-4:2021 for embedded water-based heating systems and EN 13813:2002 classification CT-C25-F7. Flexural strength at 28 d is typically 7 MPa under EN 13892-2:2002. End product types are polymer-modified cementitious screeds for heated floor systems under ceramic tile, natural stone, and engineered wood flooring.
Power-troweled concrete slabs in industrial halls carry closed surface pores and hydrophobic curing compounds that limit mechanical keying of a cementitious self-leveling underlayment. The RDP addition is specified at 2.5–4.0 wt% of total dry mix, based on a low-VOC VAE powder, to build adhesion to concrete profiles of ICRI CSP 2–4 and to reduce water uptake beneath impermeable coatings. Substrate moisture is checked under ASTM F2170-19 to a maximum 75% RH or by anhydrous calcium chloride under ASTM F1869-22 to a maximum MVER of 3 lb/1,000 ft²/24 h before application of a 3–5 mm cementitious underlayment. The dry blend is mixed in a forced-action mixer for 2–3 min, then pumped and finished with a pin rake and spiked roller. The underlayment must cure until residual moisture is below the topcoat manufacturer’s limit before epoxy, polyurethane, polymethyl methacrylate, or vinyl ester coating installation. Pull-off adhesion of the coating system is typically measured after 7 d using ASTM D7234-21, with acceptance values above 1.5 MPa across production floor areas. The underlayment conforms to EN 13813:2002 class CT-C25-F7. End product types are polymer-bonded cementitious bases under liquid-applied industrial floor coating systems in warehouses, assembly areas, and light manufacturing facilities.
Feathered edge terminations represent the lowest-consolidation zone of a self-leveling underlayment, where film thickness approaches zero and the local water loss to the substrate can arrest cement hydration before the polymer film develops full cohesion. To compensate for this boundary condition, the RDP content is raised to 4.0–5.5 wt% of total dry mortar, using a high-ethylene VAE powder with a minimum film-forming temperature below 0°C. The underlayment is hand-troweled or gauge-raked at the transition to adjacent floor coverings and is not extended beyond the wet edge. The polymer phase at the feather edge forms a continuous film after water removal, reduces microspalling under caster and foot traffic, and contributes to edge flexural strength measured by ASTM C348-21; the hardened material is classified as EN 13813:2002 CT-C25-F6. Production dry-mix is manufactured in a rotary drum mixer or twin-shaft mixer with staged addition of RDP to dispersion homogeneity; on site, water addition is controlled to the lower end of the specified flow range, 200–230 mm under EN 12706:1999, to avoid edge slumping. End product types are leveling transitions between new underlayment and existing ceramic tile, wood, or terrazzo floors, and feathered edge compounds for vinyl sheet and carpet tile installations in large-building renovation.
RDP powders with low residual monomer content and low free-formaldehyde are selected for school, hospital, and office renovation where the floor remains occupied during installation. The addition rate is 2.0–3.5 wt% of total dry mix, using a VAE grade that complies with EN 16516:2017+A1:2020 laboratory emission testing and ISO 16000-6:2021 indoor air sampling. The dry mortar is dispersed in low-dust silo systems and applied by mobile continuous mixer; area ventilation follows the general contractor’s indoor air management plan. The compound is finished to a thickness of 3–8 mm and left to cure for 24–48 h before floor covering installation when measured residual moisture meets the adhesive manufacturer’s limit. French VOC emission classification A+ is commonly specified for the installed compound. End product types are low-odor, fast-installation self-leveling underlayments beneath carpet, vinyl, and resilient flooring in occupied public buildings.
| Application boundary | Normative reference | Characterization method | Formulation limit |
|---|---|---|---|
| Tile-over-tile renovation | EN 13813:2002 class CT-C20-F6 | ASTM C1583-20 | 2.5–4.5 wt% RDP |
| Pump-applied fast-track | EN 13813:2002 class CT-C25-F6; ASTM C1708/C1708M-19 | EN 12706:1999 | 1.5–3.0 wt% RDP |
| Radiant heating screed | EN 13813:2002 class CT-C25-F7; EN 1264-4:2021 | EN 13892-2:2002 | 3.0–5.0 wt% RDP |
| Industrial coating base | EN 13813:2002 class CT-C25-F7 | ASTM D7234-21 | 2.5–4.0 wt% RDP |
| Feathered edge transition | EN 13813:2002 class CT-C25-F6 | ASTM C348-21 | 4.0–5.5 wt% RDP |
| Low-emission occupied building | EN 16516:2017+A1:2020; ISO 16000-6:2021 | French VOC class A+ | 2.0–3.5 wt% RDP |
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Redispersible polymer powder for cementitious underlayment self-leveling is a spray-dried vinyl acetate-ethylene (VAE) copolymer stabilized with polyvinyl alcohol and treated with calcium carbonate or kaolin anti-caking agents. Upon addition of water at a water-to-powder ratio of 0.20–0.25, the powder releases discrete polymer particles of 0.5–5.0 µm; these particles coalesce during the drying phase and form load-bearing polymer bridges within the cementitious matrix. Representative commercial grades include VINNAPAS 5010 N, ELOTEX FX7000, and DLP 2000. Published technical data for these VAE-based powders place bulk density between 400 g/L and 600 g/L according to ISO 60, ash residue between 8% and 13% according to ISO 3451-1, pH between 6.5 and 9.0 according to ISO 976, and minimum film formation temperature between 0 °C and 5 °C according to ISO 2115. The dry powder form enables one-component bagged underlayments with precise dosage, free of liquid latex handling, freeze-thaw instability, and in-can preservation.
In a typical cementitious underlayment formulation, ordinary Portland cement is blended with calcium aluminate cement, calcium sulfate, 0.1–0.5 mm silica sand, 1.5–4.5 wt% RDP, 0.05–0.20 wt% polycarboxylate ether superplasticizer, 0.05–0.20 wt% defoamer, and 0.05–0.20 wt% retarder. The polymer addition reduces surface dusting, improves tensile adhesion to concrete and gypsum substrates, and raises flexural strength. For standard underlayment applications, the product is applied at thickness from 1 mm to 10 mm; for thicker sections up to 30 mm, graded sand or fine gravel is added. Compared with general-purpose RDP grades used in tile adhesives, self-leveling grades are optimized for low water demand, low air entrainment, and narrower particle-size distribution after redispersion. Compared with liquid polymer dispersions, the powder form removes on-site dosing variation and avoids compatibility failures with retempering water.
Because RDP particles are already dispersed at the particle level, their influence on flow and strength is concentration-dependent and non-linear. At addition rates of 1.5–3.0 wt% of total dry mix, the polymer acts primarily as a rheology modifier and film former, with minor retardation. At 4.0–6.0 wt%, the water demand to maintain a flow spread of 250 mm on an ASTM C1708/C1708M flow table increases by approximately 2–4 percentage points; this increase is attributed to polymer particle bridging and thickening by the polyvinyl alcohol protective colloid. Simultaneously, the 24-h compressive strength may decrease by 20–40% relative to an unmodified control because the polymer film disrupts the continuous cementitious matrix and delays early ettringite formation in ternary OPC/CAC/calcium sulfate systems. Published data for this specific configuration is limited, but the directionality is consistent across commercial technical bulletins.
In production-scale dry-mix lines using a horizontal ribbon blender filled to 60–70% of working volume, high-speed addition of low-bulk-density RDP at the end of the mixing cycle reduces segregation; mixing time of 3–5 min after final component addition is sufficient when the mixer tip speed is 1.0–2.5 m/s. Overmixing beyond 10 min can generate electrostatic surface charge on spray-dried particles and increase blocking tendency during bag storage. Brookfield viscosity of the mixed slurry at 20 rpm and 23 °C typically remains below 1500 mPa·s for flowable underlayments; formulations exceeding 1800 mPa·s before the final addition of polycarboxylate ether superplasticizer exhibit leveling defects and air release problems. A defoamer based on mineral oil or polyether siloxane at 0.05–0.20 wt% is required to counter air entrainment from the redispersed polymer; without defoamer, wet density can decrease by 3–6% and 28-day flexural strength can fall by 10–15%.
Water addition is not a free variable: increasing water-to-powder ratio beyond 0.25 to compensate for viscosity rise produces bleeding, strength loss, and longer drying time. The use of high-range superplasticizer at 0.10–0.25 wt% is preferred to maintain flow without increasing water demand. Initial set measured by Vicat needle per EN 196-3 is typically shifted from 45–60 min in unmodified cementitious underlayments to 60–90 min when RDP content reaches 4.0 wt%. This retardation is partially offset by lithium carbonate accelerator at 0.05–0.10 wt% in OPC/CAC blends.
For material qualification, the following physical parameters are evaluated before production approval.
| Property | Typical range for VAE self-leveling grade | Test method |
|---|---|---|
| Bulk density | 400–600 g/L | ISO 60 |
| Residue on 315 µm screen | ≤ 2.0% | ISO 787-7 |
| Ash content | 8–13% | ISO 3451-1 |
| pH | 6.5–9.0 | ISO 976 |
| Glass transition temperature | 0–10 °C | ISO 11357-2 |
| Minimum film formation temperature | 0–5 °C | ISO 2115 |
| Film tensile strength | 2–5 MPa | ISO 527-3 |
| Elongation at break | 200–600% | ISO 527-3 |
Comparison with other product classes indicates that VAE grades offer lower minimum film formation temperature and better wet adhesion than vinyl acetate-ethylene-vinyl chloride powders; acrylic powders provide higher UV resistance and hydrolysis resistance but often require higher dosage to achieve equivalent 28-day flexural strength. For interior cementitious underlayments, VAE is selected because the polymer film does not require exterior durability and the lower minimum film formation temperature supports film formation at 5 °C application temperature. Self-leveling grades differ from tile adhesive RDPs in that they are milled or spray-dried to a lower bulk density and lower viscosity contribution. A tile adhesive RDP with bulk density above 600 g/L may reduce flow spread by 10–20 mm at the same addition, necessitating redesign of the superplasticizer package.
Transitioning from a two-component liquid latex underlayment to a one-component RDP-modified dry mix changes site logistics and application behavior. The dry mix is fed through a continuous mixing pump, such as a PFT G 4 or m-tec duo-mix, with water dosing at 0.20–0.25 water-to-powder ratio. The slurry is pumped through a 25–35 mm mortar hose and applied with a gauge rake or serrated squeegee at 1–10 mm thickness. Because the polymer is already dispersed at the particle level, mixing energy requirements are lower than for liquid latex, and the open time at 23 °C and 50% RH is typically 20–30 min, after which surface re-wetting is not permitted.
The absence of liquid latex eliminates on-site mixing errors and freeze-thaw storage failure. However, dry RDP is hygroscopic and must be stored in sealed moisture-tight packaging at relative humidity below 60%. In high-humidity environments, partial redispersion and blocking can occur within 4–6 weeks of exposure. Incompatibility with amine-based additives has been reported in some formulations, where premature coagulation or increased air entrainment occurs; additive pre-qualification is therefore necessary. Compared with polymer-free self-leveling compounds, the RDP-modified product provides higher tensile adhesion and lower water absorption, but the dry blend cost is higher and the early strength development is slower. Compared with self-leveling underlayments containing liquid latex, the dry formulation reduces variation in polymer content and eliminates the risk of adding latex to a slurry that has already exceeded the working time.
Substrate tensile adhesion after curing is assessed according to EN 13813:2002; polymer-modified underlayments typically achieve 0.8–1.5 MPa pull-off on concrete, with compressive strength class C20–C35 and flexural strength class F4–F7. Residual moisture before covering is checked by ASTM F2170, with floor covering installation generally not recommended above 80% RH for cementitious underlayments.
