What Improvements Do Admixtures Bring to GRC Performance? Which Admixtures Are Prohibited?

Admixtures are the “magicians” of GRC performance; through scientific formulation, they can significantly improve its workability, mechanical properties, and durability. Qinglong Group's 28 years of admixture application experience shows that high-quality GRC requires a four-dimensional additive system of “water reduction + setting control + toughening + functionality.” Polycarboxylate high-range water reducers can lower the water-binder ratio to 0.32-0.38, increasing compressive strength by more than 30%; retarders ensure continuity in large-area construction; polymer emulsions (such as acrylic emulsion) added at 8-12% can improve toughness by 2-3 times; hydrophobic agents reduce water absorption to below 6%. However, certain admixtures such as chloride-based accelerating agents and high-alkali activators such as sodium sulfate are strictly prohibited, as they destroy the alkali resistance of glass fibers. In the Nanning Wuxiang China Resources MixC One project, we successfully solved the bubble problem of ultra-thin GRC cladding panels (12mm thick) by compounding water reducers with defoamers, achieving a yield rate of 99%. Scientific use of admixtures is the key to upgrading GRC quality.

Water Reducers Are the Foundation of High Strength and Density

Polycarboxylate high-range water reducers with water reduction rates of up to 30-40% are the prerequisite for achieving a low water-binder ratio. Qinglong Group collaborates with top chemical companies to customize dedicated water reducers, whose sustained-release characteristics provide slump retention of over 2 hours, meeting the casting needs of large components. Through compounding water reducers with viscosity modifiers, the slurry achieves both fluidity and segregation resistance.

Polymer Emulsions Significantly Enhance Toughness

Adding 8-12% acrylate emulsion (acrylic emulsion) forms polymer films in the cement matrix, filling microcracks and raising GRC's fracture energy from the 0.1-0.2 kJ/m² of ordinary concrete to 2-4 kJ/m². As a result, Qinglong GRC's impact strength is increased by more than 3 times, truly achieving “cracking without shattering.”

Functional Admixtures Expand Application Boundaries

Adding 0.3-0.5% hydrophobic agent (such as silicone) gives GRC a contact angle of ≥90°, providing a lotus-leaf effect; adding air-entraining agents (air content of 4-6%) can improve frost resistance to above F300; colorants achieve through-coloring with weather resistance far surpassing surface coatings. These functional expansions make GRC applicable in broader fields.

The Prohibited List Is the Bottom Line of Quality Assurance

Chlorides (such as calcium chloride and sodium chloride) are strictly prohibited, as they cause rebar corrosion and fiber corrosion; high-alkali activators (such as sodium sulfate) raise the pH of the pore solution and damage fibers; composite additives with unknown ingredients should also be used with caution. Qinglong Group has established a list of prohibited substances to ensure product safety and reliability.

Admixtures are the essence of GRC technology. Through continuous R&D, Qinglong Group has mastered the synergistic effects of various admixtures, providing customers with GRC products of outstanding performance.