How Do Admixtures Improve GRC Performance? Which Admixtures Are Prohibited?

Chemical admixtures can significantly improve the workability, mechanical properties, and durability of GRC, but improper selection can have negative effects. High-quality GRC typically uses a combination of water reducers, water retainers, hydrophobic agents, and fiber dispersants, with each admixture having specific functions and usage limitations.

Through extensive testing, Qinglong GRC has determined the optimal admixture combination: polycarboxylate water reducers (water reduction rate 30%) lower the water-binder ratio to increase strength; hydroxypropyl methylcellulose (viscosity 50000 mPa·s) improves water retention and prevents plastic cracking; silicone hydrophobic agents (water absorption ratio ≤70%) improve impermeability; fiber dispersants ensure uniform fiber distribution. However, admixtures that corrode fibers and metal components, such as chloride-based accelerators and ammonium salt antifreeze agents, are strictly prohibited.

Workability-Improving Admixtures

Polycarboxylate water reducers improve flowability, with a water reduction rate ≥25%; cellulose ether water retainers reduce bleeding, with a water retention rate ≥90%; air-entraining agents improve workability, with an air content of 4%-6%. These admixtures improve construction performance.

Durability-Enhancing Admixtures

Silicone hydrophobic agents improve impermeability, with a water absorption rate ≤70%; fiber dispersants improve distribution uniformity, with a coefficient of variation ≤15%; expanding agents compensate for shrinkage, with a restrained expansion rate of 0.02%-0.04%. These admixtures improve durability.

Strictly Prohibited Admixtures

Chloride-based accelerators (Cl- ＞0.1%); ammonium salt antifreeze agents (release ammonia gas); nitrates and nitrites (corrode steel reinforcement). These admixtures are strictly prohibited.

Precautions for Admixture Use

Compatibility tests with cement must be conducted; dosage must be strictly determined through testing; pay attention to interactions between admixtures. These precautions ensure effective use.

Scientific use of admixtures can enhance product performance. Through systematic testing, Qinglong GRC determines the optimal admixture scheme.