Concrete viscosity modification agent VMA420

1. Core Performance Features

• Controlled Rheology
  • Increased Viscosity: Adjusts plastic viscosity by 20–50%, preventing segregation in high-flow or self-consolidating concrete (SCC).
  • Yield Stress Reduction: Improves flowability while maintaining cohesion (e.g., slump flow ≥600 mm with minimal segregation).
• Enhanced Stability
  • Anti-Bleeding: Reduces water separation by up to 90%, critical for vertical or overhead placements.
  • Anti-Segregation: Stabilizes mixtures with high water-to-cement ratios (e.g., underwater concrete or SCC with 180–220 mm slump).
• Pumpability Improvement
  • Reduces friction during pumping, enabling long-distance delivery (e.g., >500 m horizontal pumping for high-rise buildings).
  • Maintains homogeneity in mixtures with lightweight aggregates or recycled materials.
• Durability Enhancement
  • Minimizes capillary pore connectivity, improving chloride resistance (diffusion coefficient reduced by 30–50%).
  • Reduces surface cracking by mitigating plastic shrinkage in hot/dry conditions.

2. Key Characteristics

• Chemical Composition
  • Polysaccharide-based: Cellulose ethers (e.g., HPMC), welan gum, or diutan gum (common in bio-based VMAs).
  • Synthetic Polymers: Polyacrylamide or polyethylene oxide derivatives (offer precise viscosity control).
• Shear-Thinning Behavior
  • Exhibits thixotropy: High viscosity at rest (prevents segregation) and low viscosity under shear (eases placement).
• Compatibility
  • Synergizes with superplasticizers (e.g., PCEs) without interfering with water reduction.
  • Tolerates high salt or admixture concentrations (e.g., seawater concrete or 3D-printed mixtures).

3. Advantages

• Versatility: Suitable for SCC, underwater concrete, shotcrete, and 3D-printed structures.
• Cost Efficiency: Reduces reliance on excessive fines (e.g., silica fume) to control stability.
• Sustainability: Enables use of recycled aggregates or low-quality sands by enhancing cohesion.

4. Challenges and Solutions

5. Applications

Shotcrete: Enhances adhesion to vertical surfaces and reduces rebound.

Self-Consolidating Concrete (SCC): Ensures flow without vibration (e.g., densely reinforced structures).

Underwater Concrete: Prevents washout and cement loss (e.g., bridge piers or marine foundations).

3D-Printed Concrete: Maintains shape stability during extrusion and layer stacking.