ELOTEX FX5600

In C2-grade cementitious tile adhesives, ELOTEX FX5600 is introduced as a dry-blended redispersible polymer powder at 2.0–4.0 wt% of total dry mix, normally after the cement-sand-filler premix has reached visual homogeneity in a twin-shaft compulsory mixer with blade tip speeds of 6–8 m/s. A representative C2S1 dry mortar comprises 30–38 wt% CEM I 42.5 R, 45–55 wt% quartz sand with a 0.1–0.5 mm top cut, 5–12 wt% limestone filler, 0.35–0.55 wt% methylcellulose ether, 0.03–0.08 wt% starch ether, and 2.5–3.5 wt% FX5600. Compliance with EN 12004 C2 requires tensile adhesion of ≥1.0 N/mm² under standard, water immersion, heat ageing, and freeze-thaw test protocols per EN 1348. The polymer powder lowers brittle-fracture tendency after prolonged water storage, but does not replace correct substrate preparation; bond failure on dense concrete typically remains cohesive within the adhesive layer when open time is kept below 30 min. During field mixing, the dry mortar is stirred with 20–24 wt% clean water at paddle speed 400–600 rpm for 2–3 min, left to slake for 2 min, and re-mixed for 30 s. Wet density should be checked at 1.55–1.65 kg/L to avoid excessive air entrainment from high shear. At substrate temperatures below 5 °C, film coalescence is slowed and final adhesion may require extended curing; dry powder storage should remain below 30 °C and 60% RH to prevent irreversible agglomeration.

How Does FX5600 Modify Flow and Early Strength in Pump-Applied Self-Leveling Underlayments?

Addition windows in self-leveling compounds range from 1.5–4.5 wt% based on dry mortar; higher doses reduce yield stress and allow pump-assisted placement over large floor areas, but may extend the final set. A pump-applied CT/C formulation may combine 25–35 wt% ordinary Portland cement, 5–12 wt% calcium aluminate cement, 8–15 wt% anhydrite or alpha-hemihydrate, 40–55 wt% fine calcium carbonate or quartz filler, 0.4–1.2 wt% polycarboxylate superplasticizer, 0.1–0.3 wt% powdered defoamer, and 2.0–4.0 wt% FX5600. The governing standard EN 13813 classifies the hardened floor screed; typical specifiers select CT-C25-F6 or CT-C30-F7, requiring compressive strength of ≥25 MPa or ≥30 MPa and flexural strength of ≥6 MPa or ≥7 MPa respectively. Slump-flow measured by EN 12706 on a 30 mm × 50 mm ring should be 140–160 mm; retention over 20 min is used to approximate pump re-circulation times. Addition beyond 5.0 wt% can increase air entrainment above 3 vol% and reduce surface hardness; latex film formation may also retard early strength by 20–40% at 24 h, but final strength after 28 days generally converges. In continuous pan mixers operating at 500–800 rpm, FX5600 disperses without pre-dilution if the powder feed is introduced after the superplasticizer has begun to reduce water demand, preventing the formation of polymer-rich lumps that later appear as surface craters.

Wet or dry adhesion to aged, absorbent substrates is the primary reason for using FX5600 in sprayable and trowel-applied cementitious skim coats and wall levelling compounds. The polymer is dispersed at 2.0–4.0 wt% to control plastic shrinkage cracking and improve wet adhesion to concrete, gypsum plaster, and previously painted masonry. A white cement-based finish may include 20–30 wt% white CEM I 52.5, 45–60 wt% calcium carbonate with a top size near 40 µm, 5–10 wt% hydrated lime, 0.35–0.60 wt% hydroxyethyl methyl cellulose, 0.10–0.25 wt% starch ether, and 2.5–3.5 wt% FX5600; total mixing water is 30–38 wt%. EN 998-1 governs rendering and plastering mortars for internal and external use; adhesion of a polymer-modified skim coat to concrete is often specified above 0.7 N/mm² after 7 days dry conditioning, while overcoat adhesion for decorative finish systems is assessed by cross-cut tape pull tests rather than load-based tensile tests. Production batches are dry-mixed in ploughshare or ribbon blenders for 120–180 s; spray application uses screw-pump worm pumps operating at 200–400 rpm, while trowel application is performed in two passes, the second pass before the surface skin forms. When the skim coat is applied over gypsum substrates, a priming step with 5–10% acrylic primer dilution is required to avoid ettringite-driven interfacial failure in the presence of residual gypsum moisture.

Repair Mortar Application Limits in R2/R3 Overlay Systems

The largest process conflict in polymer-modified repair mortars arises from the competing requirements of low modulus for crack accommodation and sufficient early strength for overhead or vertical application. An R3-class remedial mortar combines OPC 30–40 wt%, 0.1–1.5 mm quartz sand, 5–8 wt% silica fume, 0.05–0.15 wt% polypropylene microfibre, and 2.5–5.0 wt% FX5600; mixing water is held at 12–16 wt% to maintain a low-sag consistency. EN 1504-3 divides PCC repair mortars into R1, R2, R3, and R4 classes. The typical R3 dataset requires compressive strength of ≥25 MPa at 28 days per EN 12190, pull-off adhesion of ≥1.5 MPa per EN 1542, restrained shrinkage below 0.8 mm/m for polymer-modified systems, and chloride ion content below 0.05%. Mechanical mixing uses low-speed helical paddle mixers at 600 rpm to avoid air entrapment; material is pressed into primed saturated-surface-dry concrete in lifts not exceeding 20 mm per pass. Rebound on vertical surfaces is reduced when wet density is controlled at 1.90–2.10 kg/L. FX5600-modified R3 mortar should not be used as a standalone structural R4 material without supplemental steel or fibre reinforcement; at service temperatures above 40 °C, creep under sustained load may exceed unreinforced polymer-bound mortar limits.

When Crack-Bridging Waterproofing Slurries Require Low-Temperature Flexibility

Flexible cementitious waterproofing slurries commonly use 3.0–6.0 wt% FX5600 to meet crack-bridging requirements at −10 °C. A one-component dry mortar for this application contains 30–40 wt% CEM I 42.5 R, 40–55 wt% quartz sand with a top size of 0.25 mm, 5–10 wt% microsilica, 0.05–0.20 wt% cellulose ether, and 0.2–0.5 wt% powdered defoamer. EN 14891 governs liquid-applied water impermeable products used beneath ceramic tiling; key test provisions include initial adhesion, adhesion after water immersion, water impermeability under positive pressure, and crack-bridging capability. Crack-bridging capacity for flexible polymer-modified slurries is generally declared at 0.4–0.8 mm at 23 °C, narrowing to 0.2–0.3 mm at −10 °C; the lower boundary is the operational limit for balcony transitions and basement movement joints. Application is by stiff brush or notched trowel in two passes; the first pass at 1.0–1.5 mm is reinforced with alkali-resistant glass fibre mesh at corners and movement joints before the second pass reaches 2.0–3.0 mm total dry film thickness. FX5600-modified slurries are positive-side waterproofing membranes; they are not designed for sustained negative hydrostatic pressure unless the substrate has been injection-grouted or otherwise isolated from groundwater ingress.

Gypsum-Based Joint Fillers and Plaster Hardness Retention

In gypsum joint fillers, the dosage of FX5600 is kept at 1.0–2.5 wt% because higher polymer levels reduce surface hardness and extend sanding time beyond 24 h. A beta-hemihydrate-based compound uses 60–75 wt% stucco, 20–30 wt% limestone filler, 0.25–0.50 wt% cellulose ether, 0.01–0.05 wt% protein-based or tartaric acid retarder, and 1.5–2.0 wt% FX5600. ASTM C475 governs interior gypsum joint compounds; critical parameters include joint cohesion, working time, and sanding resistance. EN 13279-1 applies to gypsum plaster and defines the B1–B7 classes; jointing compounds are often specified under EN 13963 for gypsum board finishing. Mixing uses slow-speed equipment at 400–500 rpm for 30–60 s, followed by 60 s slaking; working time is typically 60–120 min. Viscosity under Brookfield spindle 5 at 10 rpm is adjusted to 40–60 Pa·s to allow trowel spreading without sag on vertical joints. At 2.5 wt% or above, polymer film formation can reduce water vapour permeability and increase sanding effort, potentially interfering with paint adhesion at butt joints.

Because ETICS base coat mortars must accommodate cyclic thermal stresses across 1200 × 600 mm expanded polystyrene boards, FX5600 is included at 2.5–4.0 wt% to improve molecular relaxation and crack resistance of the glass-fibre-reinforced base coat. A base coat mortar under ETAG 004 or EAD 040083-00-0404 contains 25–35 wt% CEM I 42.5 R, 45–55 wt% washed quartz sand with maximum grain 0.5 mm, 5–10 wt% calcium carbonate, 0.30–0.50 wt% methyl cellulose, 0.10–0.30 wt% hydrophobic additive, and 3.0–3.5 wt% FX5600; the wet mortar is reinforced with 160 g/m² alkali-resistant glass fibre mesh embedded in the outer third. Application is by notched trowel at 4–6 mm wet thickness; the mesh is pressed into the fresh mortar and immediately covered. Curing at 20 °C/60% RH is required for 24–48 h before decorative render is applied. The base coat is not a UV-resistant finish; prolonged exposure beyond 4 weeks before topcoat application may require re-priming and interlayer adhesion checks. Published data for this specific FX5600 configuration is limited, so exterior qualification testing must be run on the final binder-filler composition before system approval is filed.