VINNAPAS 546 ND VAE Emulsion for Waterproofing Mortars

In cold-climate waterproofing applications where cementitious slurries must retain elongation at sub-zero temperatures while resisting hydrostatic pressure from groundwater, the polymer dispersion governs not only initial crack-bridging capacity but also long-term hydrolytic stability under saturated lime conditions. VINNAPAS 546 ND, an aqueous copolymer dispersion of vinyl acetate and ethylene (VAE), is supplied with a solids content of 50–52 %, a Brookfield RVT viscosity (spindle 3, 20 rpm) of 200–800 mPa·s at 23 °C, and a pH of 4.0–5.0. The dispersion is APEO-free, stabilized with a polyvinyl alcohol protective colloid, and carries a minimum film-forming temperature (MFFT) of 0 °C and a glass transition temperature (Tg) near -7 °C. These parameters position the grade within the high-ethylene segment of VAE binders, where the increased ethylene mole fraction delivers greater chain flexibility, reduced equilibrium water sorption, and enhanced resistance to alkaline saponification compared to low-ethylene VAE copolymers.

What Distinguishes a High-Ethylene VAE Dispersion in Hydraulically Setting Systems?

Conventional VAE dispersions with ethylene contents below 15 mol% undergo progressive hydrolysis of acetate groups when exposed to the 12.5–13.5 pH aqueous pore solution of hydrating cement. The liberated acetic acid reacts with calcium hydroxide to form calcium acetate, a mobile salt that can effloresce and enlarge capillary pores. By elevating the ethylene fraction to approximately 20–25 mol%, VINNAPAS 546 ND reduces the ester group density along the polymer backbone, slowing the alkaline attack rate by a factor of 2–3 relative to standard grades with Tg above 0 °C. This compositional shift also depresses the Tg into the sub-zero range, ensuring that the polymer remains elastomeric at the -5 °C test temperature mandated by EN 14891 for liquid-applied water impermeable products. The internal plasticization effect of ethylene sequences eliminates the need for external coalescing agents or phthalate plasticizers that can migrate and embrittle over time.

The anionic/nonionic stabilization system, dominated by PVOH, interacts with multivalent cement cations (Ca²⁺, Al³⁺) to form a composite polymer-cement matrix. During hydration, the polymer particles flocculate and eventually coalesce into a continuous film that encapsulates hydrated phases and bridges microcracks. Unlike styrene-butadiene rubber (SBR) latex, which relies on carboxylated styrene-butadiene chains for colloidal stability and possesses inherent resistance to ester hydrolysis, the VAE binder offers superior adhesion to damp substrates and lower air-entraining tendency when mixed at high shear. The difference becomes critical in two-component waterproofing slurries applied by trowel or roller, where a pinhole-free coating with wet adhesion exceeding 0.5 MPa (EN 14891, method 7.2) is required.

Formulating a flexible waterproofing slurry with VINNAPAS 546 ND typically targets a polymer-to-cement ratio (p/c) of 0.10–0.20 on a dry polymer basis, corresponding to a dispersion addition of 20–40 parts per hundred parts of cementitious powder. At p/c ≥ 0.15, the polymer content exceeds the critical pigment volume concentration, yielding a co-continuous matrix after curing that provides a water absorption coefficient below 0.1 kg/(m²·h^0.5) measured per EN 1015-18. Tensile strengths at 28 days of dry curing typically range from 1.5 to 2.5 MPa, with elongation at break of 200–400 % when tested according to ISO 37 type 2 dumbbell specimens at a crosshead speed of 200 mm/min. However, these mechanical values are strongly dependent on the cement type—a CEM I 52.5 R accelerates early strength development but can generate excessive heat of hydration that prematurely dehydrates the polymer film before coalescence is complete. Trials in a 500-litre planetary mixer have shown that substituting 15–20 % of the ordinary Portland cement with a fine limestone filler (d₅₀ 10 µm) moderates the hydration exotherm and extends the film-formation window by approximately 30 minutes at 23 °C.

Coalescence Kinetics and the Critical Pigment Volume Concentration of Hydrating Systems

Despite a nominal MFFT of 0 °C, the polymer film in a cementitious slurry effectively coalesces at application temperatures as low as -5 °C without the addition of volatile coalescing aids. This apparent contradiction is explained by the combined effect of cement pore water alkalinity and dissolved salts. Calcium and sodium hydroxides in the pore solution plasticize the PVOH stabilizer sheath, lowering its Tg and promoting interdiffusion of polymer chains across particle boundaries. In addition, osmotic dehydration driven by cement hydration concentrates the dispersion, increasing the capillary pressure that drives particle deformation, while the exothermic hydration reaction locally raises the paste temperature by 5–8 K within the first 6 hours. The real-time film formation can be monitored by measuring electrical resistance across a 2 mm wet film thickness: a resistance increase from <1 kΩ to >100 kΩ over 24 hours at -5 °C indicates the formation of a continuous insulating polymer phase.

The driving force for particle deformation follows the classical capillary model where the pressure difference across the air–water meniscus is P = 2γ/r. Here γ, the surface tension of the aqueous polymer dispersion, is depressed from roughly 40 mN/m to 25–30 mN/m by the PVOH colloid and soluble cement salts. As hydration consumes free water, the effective pore radius r decreases toward the interparticle spacing of packed polymer particles (~100–200 nm), generating capillary pressures in the 0.3–0.6 MPa range—sufficient to deform the soft VAE particles and drive coalescence. When the polymer volume fraction exceeds approximately 0.18, a percolating network forms; below this threshold, the polymer remains as isolated domains and the cured morphology exhibits continuous capillary pores detectable by mercury intrusion porosimetry (pore diameters >0.1 µm). In production-scale trials, exceeding a p/c of 0.25 resulted in increased drying shrinkage cracking because the polymer-dominated matrix lacks the rigidity of the inorganic framework.

Failure to coalesce—observed when the cement contains excessive amounts of rapidly dissolving alkali sulfates (> 3 % K₂SO₄ equivalent)—results in a powdery, non-film-forming surface and a water impermeability failure under EN 14891. Pre-hydration of the cementitious powder by extended silo storage at relative humidity > 65 % also deactivates surface sites and retards the ionic flux needed for PVOH plasticization, reducing coalescence depth.

When the Mix Water Contains Dissolved Salts or Sulfates

Groundwater and brackish mixing water often carry chloride concentrations up to 5000 mg/L and sulfate levels reaching 2000 mg/L. These ions compete with polymer stabilizers and can destabilize the dispersion during mixing, causing coagulum formation and inhomogeneous film distribution. VINNAPAS 546 ND, owing to its nonionic PVOH protective colloid, exhibits tolerance to electrolytes superior to purely anionic surfactant-stabilized dispersions. Jar tests with synthetic seawater (ASTM D1141) demonstrate that up to 20 vol% seawater can be used as mixing water without visible coagulation when the dispersion is pre-diluted with fresh water at a 1:1 ratio. For sulfate-rich groundwaters, the sulfate resistance of the hardened mortar itself can be augmented by incorporating a microsilica (silica fume) addition of 5–10 % by mass of cement, which consumes portlandite and lowers the Ca/Si ratio of the C-S-H phase, reducing expansive ettringite formation. The polymer film, once coalesced, acts as an ionic barrier, reducing chloride diffusion coefficients by an order of magnitude compared to unmodified cement paste (from 10⁻¹¹ m²/s to 10⁻¹² m²/s as measured by rapid chloride migration test, NT Build 492).

The compliance framework governing polymer-modified waterproofing slurries includes multiple standards, each addressing a distinct failure mechanism. A subset of the testing mandated for a CE-marked liquid-applied waterproofing membrane using VINNAPAS 546 ND is tabulated below; the results represent a formulation with p/c 0.15, filler-modified cement, and dry film thickness 2.0 mm after 28 days at 23 °C, 50 % RH.

Comparative performance data of a flexible waterproofing slurry based on VINNAPAS 546 ND versus a conventional SBR latex and an acrylic dispersion, all formulated at p/c 0.15 with CEM I 42.5 N, is summarised below. The crack-bridging value of 0.75 mm at -5 °C for the 546 ND formulation exceeds the 0.5 mm threshold for Class CM01P products under EN 14891, enabling use in below-grade waterproofing exposed to freeze-thaw cycles in central and northern European climates. A dry film thickness of at least 1.5 mm is required to achieve this value.

Mitigating Air Entrapment during High-Shear Continuous Mixing

When preparing slurry in a continuous ring-layer mixer or a high-shear colloidal mill for spray application, the interaction between the PVOH-stabilized dispersion and the mixing geometry can generate stable microfoam with bubble diameters of 10–50 µm, increasing the capillary porosity after curing and reducing water impermeability. Defoamer selection must account for compatibility with the nonionic system; a mineral oil-based defoamer with hydrophobic silica, dosed at 0.3–0.8 % on total liquid weight, achieves air contents below 3 % (EN 1015-7) without causing fisheyes. In rotor-stator mixers operating at 3000 rpm, the shear rate can locally exceed 50,000 s⁻¹, breaking the polymer particles and releasing coalesced PVOH fragments that act as foam stabilizers. To counteract this, the dispersion is typically added after 60 % of the fill water has been mixed with the powder, followed by a gentle homogenization phase at 500 rpm for 2 minutes before a final 30-second high-shear burst at 2000 rpm. Failure to control air content results in a cured membrane with visible pinholes and a watertightness failure under 5 bar of hydrostatic pressure.

At 23 °C and 50 % relative humidity, a slurry containing 40 parts VINNAPAS 546 ND dispersion per 100 parts of dry powder exhibits a pot life of 45–60 minutes, defined as the interval during which the viscosity remains below 150,000 mPa·s on a Brookfield Helipath T-bar spindle (0.5 rpm). Beyond this window, the gradual coalescence triggered by cement hydration leads to irreversible thickening and a granular texture that prevents trowel or roller application. On vertical surfaces, the slurry must be applied in two coats at a wet thickness of 1.0–1.5 mm per coat, with a recoat interval of 4–6 hours at 20 °C to allow sufficient water evaporation for polymer film formation without over-drying the cement matrix. In hot-wind conditions (> 30 °C, < 30 % RH), the addition of 2–3 % of a low-viscosity cellulose ether (viscosity 400 mPa·s as 2 % solution) is required to extend the open time and prevent plastic shrinkage cracking.

Equipment cleaning: uncured slurry is water-miscible and can be flushed from pumps and hoses with cold water within 2 hours of mixing. After curing, polymer-cement residues require mechanical removal or prolonged soaking with acidic cleaners (pH 2–3), as the coalesced VAE film resists simple dissolution. VINNAPAS 546 ND must not be co-formulated with hard water containing > 400 ppm Ca²⁺ without prior chelation, as calcium ions can bridge PVOH chains and induce macroscopic gelation during storage of the liquid component. Direct mixing with rapid-hardening cement (CEM 52.5R) without retarder can cause flash setting, reducing workable time to under 10 minutes and entrapping mixing water, which later evaporates and leaves pinholes. The dispersion is free of intentionally added biocides when shipped; therefore, premixed liquid-powder combinations intended for long-term liquid component storage require a biocide package suitable for alkaline, high-solids emulsions, such as a combination of CMIT/MIT at 10–15 ppm active ingredient and a formaldehyde releaser.