Concrete defoamer DF141

Performance Characteristics of Concrete Defoamers

The performance characteristics of concrete defoamers are organized below in a structured and itemized manner:

1. Elimination of Harmful Bubbles

• Mechanism: Reduces bubble surface tension or destabilizes bubble membranes, promoting the rupture of large bubbles and coalescence of small bubbles, thereby reducing unevenly distributed pores in concrete.
• Target: Primarily eliminates mechanically entrained bubbles (not the closed micro-bubbles introduced by air-entraining agents) generated during mixing or construction.

2. Enhanced Density and Strength

• Reduced Porosity: Minimizes residual harmful bubbles (diameter >1mm), optimizing the internal structure of concrete and improving compressive and flexural strength.
• Improved Durability: Reduces interconnected pores, enhancing impermeability, freeze-thaw resistance, and resistance to chemical erosion.

3. Improved Surface Quality

• Reduced Surface Defects: Eliminates surface bubbles, resulting in smoother and denser concrete surfaces, ideal for decorative or exposed architectural concrete.
• Lower Repair Costs: Avoids post-construction repairs caused by bubble-induced defects.

4. Optimized Rheological Properties

• Reduced Bleeding: Suppresses slurry carried upward by rising bubbles, minimizing segregation and improving homogeneity.
• Pumpability: Reduces interference of bubbles with flowability in high-fluidity concrete (e.g., self-compacting concrete).

5. Synergy with Air-Entraining Agents

• Differentiation and Complementarity:
  • Air-Entraining Agents: Introduce uniformly distributed, closed micro-bubbles (20–200 μm) to improve freeze-thaw resistance.
  • Defoamers: Eliminate harmful large bubbles. The two can be combined to optimize the bubble system.
• Note: Optimal blending ratios must be determined through testing to avoid excessive defoaming that negates the benefits of air-entraining agents.

6. Types and Chemical Properties

• Common Types:
  • Silicone-Based: Highly efficient but may affect concrete hydrophilicity.
  • Polyether-Based: Stable with good compatibility with other admixtures.
  • Mineral Oil-Based: Cost-effective but may leave oily residues affecting surface treatments.
• Eco-Friendliness: Select non-toxic products free of volatile organic compounds (VOCs).

7. Application Scenarios

• High-Strength Concrete: Minimizes bubble-induced strength reduction.
• Precast Elements: Enhances surface smoothness to meet aesthetic requirements.
• Underwater Concrete: Reduces risks of loose structures caused by bubble buoyancy.

8. Usage Considerations

• Precise Dosage: Overdosing may increase viscosity or reduce workability (typical dosage: 0.01%–0.1% of binder weight).
• Timing of Addition: Best added during the late mixing stage to avoid direct contact with air-entraining agents, which may cause inefficacy.
• Environmental Adaptability: Adjust formulations for high-temperature or high-alkali environments that may reduce defoaming efficiency.