GRC Admixture Application Guide: Performance Improvement and List of Prohibited Categories

Admixtures empower GRC performance, and scientific selection is the core. As an important component of GRC materials, admixtures can significantly improve the construction performance, mechanical properties, and durability of products, but improper selection or the use of prohibited admixtures can bring quality risks to GRC. Drawing on 28 years of production experience, Qinglong Group explains in detail the beneficial effects of GRC admixtures and the prohibited types, providing the industry with a scientific selection reference.

#Core Beneficial Effects of Admixtures on GRC Performance Suitable admixtures can enhance GRC performance in many ways. First, enhancing mechanical properties: adding high-range water reducers can lower the water-binder ratio and improve the density, compressive strength, and flexural strength of the GRC matrix. In the production of large components, Qinglong uses polycarboxylate-based high-range water reducers, which can increase GRC flexural strength by more than 20%; adding early-strength agents speeds up cement hydration reactions and shortens the curing period, meeting the needs of projects with tight schedules. Second, optimizing construction performance: retarders can extend the setting time of GRC slurry, preventing premature setting in the production of complex components and ensuring construction continuity; air-entraining agents introduce tiny air bubbles, improving the fluidity and workability of the slurry, making it easier to fill molds and enhancing the surface smoothness of components. Third, improving durability: waterproofing agents can reduce the water absorption of GRC and enhance its impermeability, suitable for projects in humid environments; antifreeze agents improve the material's freeze-thaw resistance, meeting the requirements for use in cold northern regions; corrosion inhibitors can suppress chloride ion corrosion of metal components, extending the service life of GRC.

#Types of Admixtures Prohibited in GRC Production To ensure GRC product quality and safety, certain admixtures are explicitly prohibited. First are chloride-containing admixtures, such as chloride-based early-strength agents and antifreeze agents containing calcium chloride or magnesium chloride. Chloride ions can cause excessive chloride content in GRC materials, corrode metal embedments, and reduce material durability—this is the most strictly prohibited type of admixture in GRC production. Second are high-alkali admixtures, such as those containing sodium hydroxide or potassium hydroxide, which raise the alkalinity of the GRC system, corrode alkali-resistant glass fibers, and cause fiber strength degradation, affecting the mechanical properties and service life of GRC. In addition, admixtures containing harmful organic substances are prohibited—such as the formaldehyde and benzene compounds found in some inferior water reducers, which can interfere with cement hydration reactions, resulting in insufficient GRC matrix strength while also polluting the environment. Expired or deteriorated admixtures are also prohibited, as their unstable performance can easily cause problems such as abnormal slurry setting and reduced strength.

#Principles for the Scientific Selection of Admixtures Qinglong Group follows three major principles in admixture selection. First is the compatibility principle: select suitable admixtures according to the service environment, production process, and performance requirements of GRC—for example, coastal projects should use salt-fog-resistant admixtures, and spray-up processes should use water reducers with good flowability. Second is the compliance principle: select admixtures that comply with national standards, giving priority to chlorine-free, low-alkali, and environmentally friendly products, such as polycarboxylate-based water reducers and alkali-free retarders, while requiring suppliers to provide product test reports to verify their composition and performance. Third is the precise proportioning principle: admixture dosage must be strictly controlled, as excessive addition may trigger negative effects—for example, an excessively high water reducer dosage can lead to slurry bleeding and reduced strength, while excessive retarder can extend setting time and affect production efficiency. Qinglong determines the optimal dosage through testing to ensure admixtures deliver their best results.

#Quality Control in Admixture Use The use of admixtures must be accompanied by strict quality control. Qinglong Group has established an incoming inspection system for admixtures: every batch is tested upon arrival for indicators such as active ingredients, alkalinity, and chloride ion content, and may only be used after passing inspection; during production, automated metering equipment is used to precisely control admixture dosage and avoid errors from manual addition; compatibility tests of admixtures are conducted regularly to verify their suitability with cement, aggregates, and glass fibers, ensuring no adverse reactions. Meanwhile, admixture types and dosages are dynamically adjusted according to actual project conditions—for example, appropriately increasing the antifreeze agent dosage in winter production and adjusting the retarder ratio in summer production—to ensure stable product quality.

Scientific selection and standardized use of admixtures are key to improving GRC performance. With its professional technical team and strict quality control, Qinglong Group achieves the optimized application of admixtures, providing customers with high-quality products. If needed, I can help you compile a **GRC Admixture Selection and Usage Standards Manual**, covering applicable scenarios, dosage standards, prohibited lists, and more, to support standardized production.