Composite Protein-Based vs. Amino Acid-Based Gypsum Retarders
Created on 2025.12.30
A Comprehensive Analysis of Their Effects on Gypsum Plaster Performance
In gypsum plaster systems, retarders play a critical role in controlling setting time, strength development, and microstructural evolution. Among the commonly used products, composite protein-based retarders and amino acid-based retarders represent two distinct technical routes with markedly different performance profiles.
This article provides a systematic comparison from the perspectives of mechanism, performance impact, and practical application.
1. Effects of Composite Protein-Based Gypsum Retarders
Composite protein retarders are typically produced by acid hydrolysis of animal or plant proteins, followed by modification or compounding. They have been widely used in the gypsum industry for many years.
Key Characteristics
Strong retarding effect
These retarders significantly extend the initial and final setting time of gypsum, providing sufficient working time and generally outperforming inorganic salt retarders in retarding efficiency.
Trade-off between retardation and strength
A common limitation is that stronger retarding effects are often accompanied by greater strength loss in the hardened gypsum.
Modification of crystal morphology
Protein-based retarders alter the hydration products of gypsum, transforming dense interlocking needle-like dihydrate crystals into shorter, thicker plate- or column-shaped crystals.
This reduces crystal interlocking, increases porosity and pore size, and ultimately leads to reduced mechanical strength.
Technical Improvements
Chemical compounding
By combining hydrolyzed proteins with organic acids or phosphonates (e.g., aminotrimethylene phosphonic acid, malic acid) at optimized ratios, both retarding efficiency and strength retention can be improved.
Physical modification
Some products use carriers such as perlite to improve dispersion in dry-mix mortars, extend the interval between initial and final set, and reduce concentrated heat release during hydration.
2. Effects of Amino Acid-Based Gypsum Retarders
Amino acid-based retarders represent a technological upgrade over traditional protein-based systems and are produced via chemical synthesis with designed molecular structures. Typical products include KH-GR801.
Core Advantages
Low dosage · High efficiency · High strength retention
Effective retardation can be achieved at very low dosages (typically 0.02%–0.30% of total binder), with minimal impact on long-term strength.
Optimized microstructure regulation
Unlike citric acid and similar retarders that degrade crystal morphology, high-quality amino acid-based retarders promote controlled crystal coarsening, resulting in a denser and more uniform microstructure.
Excellent application adaptability
These products offer good water solubility, high dispersibility, and excellent compatibility with various gypsum sources and other admixtures, making them suitable for industrial-scale production.
3. Comparative Analysis and Application Guidance
Key Differences
- Strength impact:
Composite protein retarders often cause noticeable strength loss, while amino acid-based retarders are designed to preserve strength.
- Efficiency:
Amino acid-based retarders achieve precise setting control at lower dosages.
- Technical essence:
Amino acid-based systems rely on molecular-level crystal growth regulation rather than simple physical adsorption or film formation.
Application Recommendations
- Compatibility testing is essential:
Due to wide variations in gypsum sources and impurities, optimal dosage must be determined experimentally.
- Consider the full admixture system:
Retarders must work synergistically with water reducers and cellulose ethers.
- Performance-oriented applications:
For machine-applied plaster and gypsum self-leveling systems, amino acid-based retarders are preferred.
- Cost-sensitive formulations:
Optimized composite protein retarders remain a viable option.
Final Insight
Selecting a gypsum retarder is ultimately a balance between workability, mechanical performance, and formulation cost.
Amino acid-based retarders lean toward high-performance solutions, while composite protein-based retarders continue to serve as economical, practical options.
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