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Self-Leveling Compound Additives

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Introduction

Self-leveling compound (SLC) additives are precision rheology modifiers and polymer binders that enable pumpable, free-flowing floor leveling products to spread under gravity into a flat, defect-free surface without troweling. The formulation challenge in SLC is unique: the compound must flow freely at the moment of pouring, resist segregation and bleeding during flow, and then gain sufficient early strength to allow foot traffic within 2–4 hours.

Cellulose ethers at very low dosage (0.03–0.15%) are used as anti-segregation and rheology stabilizers in SLC. Redispersible polymer powders improve flexibility, tensile strength, and adhesion to the substrate. The precise balance between fluidity and early set is what separates a high-performing SLC from a formulation that bleeds, cracks, or takes excessive time to achieve walking strength.

Specification

Parameter Low-Viscosity HPMC (SLC Grade) HEC (SLC Grade) RDP (SLC Grade)
Viscosity (2%, 20°C) 400–15,000 mPa·s 400–6,500 mPa·s N/A
Recommended dosage (%) 0.03–0.12 0.03–0.10 0.5–2.0
Water retention effect High Moderate–High Low (indirect)
Flow improvement Moderate Good Good
Anti-bleed function Good Moderate Low
Early strength effect Neutral Neutral Positive
Ash content (%) ≤5 ≤5 ≤10
Moisture (%) ≤5 ≤5 ≤2
Particle size (mesh) 100–120 100–120 400–600 μm

SLC additives are supplied in 25 kg bags. Custom viscosity cuts and co-ground blends available for high-volume customers.

Application

  • Cement-based SLC (floor leveler): Low-viscosity HPMC at 0.05–0.10% controls bleed water and stabilizes the suspension without restricting flow spread.
  • Gypsum-based SLC (anhydrite screed): HEC at 0.03–0.08% is preferred in calcium sulfate-based systems due to its compatibility with sulfate-rich binders and absence of methoxyl groups.
  • Rapid-hardening SLC: Ultra-low dosage HPMC (0.03–0.05%) in aluminate cement-based systems maintains flow without delaying early strength gain — critical for 2-hour foot-traffic requirements.
  • Micro-topping and design floors: Thin-layer SLC (2–5 mm) uses RDP at 1.5–2.5% combined with low-viscosity HPMC to ensure adhesion to the existing substrate and prevent thin-layer cracking.
  • Heated floor underlayment: RDP at 1.0–2.0% adds flexibility to accommodate thermal cycling above underfloor heating circuits.
  • High-traffic industrial floors: Medium-compressive-strength SLC (≥30 MPa) uses optimized low-dosage HPMC + RDP to meet EN 13813 CT-C30-F6 classification.

Advantage

  • Bleed water control without sacrificing flow: Our low-viscosity HPMC grades at 0.05–0.10% dosage achieve ≥220 mm spread diameter (Hägerdie flow table) while maintaining a bleed water ratio below 0.5% — a performance combination difficult to achieve with conventional thickeners.
  • Compatibility with fast-setting binder systems: Low-dosage, fast-dissolving grades do not retard CSA or aluminate cements, enabling 2-hour foot-traffic SLC formulations.
  • Substrate adhesion improvement via RDP: RDP at 1–2% significantly improves pull-off strength to concrete and existing tile substrates, preventing delamination under dynamic loading.
  • Crack resistance in thin layers: RDP-modified SLC formulations maintain ≥2.5 N/mm² flexural strength (EN 13892-2) in 5–10 mm layers where unmodified cement systems crack under point loading.
  • Consistent performance across climates: Our SLC-grade HPMC is available in temperature-stable variants that maintain dissolution rate and rheology contribution in both cold (5°C) and hot (35°C) pour conditions.
  • Easy integration into existing plant processes: Fine particle grades (100–120 mesh) disperse rapidly in continuous mixer systems without agglomeration or fish-eye formation.
  • Q: Why is very low viscosity HPMC used in self-leveling compounds rather than standard building grades?
  • A: Standard building-grade HPMC (40,000–200,000 mPa·s) creates too much viscosity in SLC formulations even at very low dosage, restricting the free flow that self-leveling requires. Low-viscosity SLC grades (400–5,000 mPa·s) provide the anti-bleed and segregation resistance function without creating a gel network that limits spread. The art is achieving flow of ≥220 mm while preventing bleeding — our SLC grades are specifically optimized for this balance.
  • Q: Is HEC better than HPMC for gypsum-based self-leveling screeds?
  • A: In calcium sulfate anhydrite (CAF) screed systems, HEC is generally preferred over HPMC. The methylcellulose substituents in HPMC can interfere with the sulfate-rich pore solution chemistry in some anhydrite binders, causing set irregularity. HEC, which carries only hydroxyethyl groups, is chemically inert in sulfate systems and provides smooth rheology control without binder interaction. We produce both HPMC and HEC SLC grades and can advise based on your specific binder.
  • Q: What dosage of RDP should I use in a rapid-hardening SLC?
  • A: In rapid-hardening SLC systems (CSA or aluminous cement, 2-hour foot traffic), keep RDP dosage to 0.5–1.0%. Higher RDP content can slow early hydration, delaying the strength gain that defines rapid performance. At 0.5–1.0%, RDP still meaningfully improves adhesion pull-off strength and reduces shrinkage cracking without compromising the 2-hour walking strength target.
  • Q: Can your additives help achieve the CT-C25-F4 classification under EN 13813?
  • A: Yes. A well-optimized formulation using our low-viscosity HPMC at 0.06–0.10% and RDP at 1.0–1.5% in a standard Portland/calcium aluminate hybrid binder system can reliably achieve CT-C25-F4 or better classification. We can provide reference formulations and third-party test data from EN 13892 testing conducted on our additive grades. Contact our technical team with your target binder composition for a specific recommendation.
  • Q: What is the minimum order for SLC-grade additives?
  • A: Minimum export order is 500 kg per grade. For customers sourcing multiple SLC additive types (HPMC + RDP, or HPMC + HEC), we can consolidate into a single LCL shipment from Ningbo. Trial sample quantities (200 g–1 kg) are available free of charge for qualified buyers with a defined formulation development project.
About Us
Zhejiang Yisheng New Material Co., Ltd.
Zhejiang Yisheng New Material Co., Ltd. is a professional enterprise engaged in the design, development, manufacturing, application, and sales of cellulose ether, located in the Shangyu Economic and Technological Development Zone, part of the Hangzhou Bay National Industrial Park. With a core concept of safety, environmental protection, and sustainable development, the company boasts an annual production capacity of 15,000 tons of cellulose ether, offering a complete range of products including HEC (hydroxyethylcellulose), HEMC (hydroxyethyl methylcellulose), and HPMC (hydroxypropyl methylcellulose). Our products serve various sectors such as oil fields, coatings, dry powder mortar, cosmetics, personal care products, medicine, and many others. Yisheng has a global presence, providing stable cellulose ethers and services to customers worldwide.
As a professional China Self-Leveling Compound Additives Supplier and Self-Leveling Compound Additives Company, The company adheres to the principles of safety and environmental protection as the foundation of its development. It implements and further consolidates safety and environmental protection measures, striving to create green and environmentally friendly production processes, safe and effective control systems, and orderly production management. This approach lays a solid foundation for the company's sustainable development. Yisheng boasts a scientific management mechanism, a comprehensive quality management system, stringent product testing methods, advanced technology, state-of-the-art equipment, and high-quality after-sales service.
Zhejiang Yisheng New Material Co., Ltd.

+86-18067879812
Zhejiang Yisheng New Material Co., Ltd.

sarah@ys-cellulose.com
Zhejiang Yisheng New Material Co., Ltd.