The Improving Effect of Admixtures on GRC Performance and a Discussion of Prohibited Admixture Types

### The Role of Admixtures in Improving GRC Performance and Prohibited Admixture Types

Performance breakthroughs in GRC materials require both the "addition" of technological innovation and the "subtraction" of controlling prohibited admixtures.

In the field of architectural decoration, GRC (glass fiber reinforced concrete) has become the preferred material for high-end projects such as grand theaters, commercial complexes, and landmark buildings, thanks to its advantages of light weight, high strength, and flexible styling. As an industry leader with 28 years of expertise in UHPC/GRC/GRG/GRP materials, Qinglong Group deeply understands the core role of admixtures in GRC production—they are not only the "catalyst" for performance optimization, but also the "gatekeeper" of quality and safety. Starting from technical principles, this article analyzes the mechanisms by which admixtures improve GRC performance, and clarifies the types of admixtures prohibited in the industry and their risks, providing a professional selection reference for designers and owners.

#### I. How Do Admixtures "Empower" GRC Performance?

The performance improvement of high-quality GRC is inseparable from the scientific proportioning of admixtures. In Qinglong Group's production system, admixtures optimize the material through three pathways:

**1. Enhancing Workability, Improving Forming Efficiency** Water reducers are among the most commonly used admixtures in GRC production. By reducing the surface tension of the cement paste, they can significantly improve the flowability of the mix without increasing water content, allowing glass fibers to bond more uniformly with the cement matrix. For example, in the production of double-curved GRC cladding panels for a landmark project in Nanjing, Qinglong adopted a customized water reducer formula, shortening the component forming cycle by 20% while ensuring surface precision errors of ≤2mm.

**2. Optimizing Mechanical Properties, Strengthening Structural Stability** The synergistic use of accelerating agents and retarders is key to controlling GRC strength development. Practice at Qinglong's production base in Nanning, Guangxi shows that the proper addition of accelerating agents can raise the 7-day flexural strength of GRC products to over 20MPa, meeting rapid demolding requirements, while retarders can prevent "false setting" in high-temperature environments, ensuring the uniform internal structure of large components (such as Roman columns and cornice lines). This "rigidity and flexibility combined" control approach has enabled Qinglong GRC to demonstrate excellent crack resistance in projects such as the Dongguan Women and Children's Activity Center.

**3. Improving Durability, Extending Service Life** The application of antifreeze agents and waterproofing agents directly affects GRC durability in complex environments. The Technical Standard for Building Application of Glass Fiber Reinforced Cement (GRC) (JGJ/T423-2018), which Qinglong participated in formulating, explicitly requires that composite antifreeze agents be added in projects in cold regions to ensure a strength loss rate of ≤15% after 200 freeze-thaw cycles. In addition, the incorporation of inorganic waterproofing agents can reduce the water absorption of GRC to below 8%, effectively resisting the erosion of components by the humid southern environment.

#### II. Warning! These Admixtures Are Explicitly Prohibited in the Industry

Not all admixtures "add points" to GRC. Although some cheap or non-compliant additives can reduce short-term costs, they can create serious hidden quality hazards. Based on Qinglong Group's 28 years of project experience and industry standards, the following types of admixtures must be strictly prohibited:

**1. Chloride-Based Admixtures: The "Invisible Killer" Causing Steel Corrosion** Although chloride-based accelerating agents such as calcium chloride can rapidly increase strength, they cause corrosion of the steel bars or embedded parts inside GRC, leading to component cracking and falling off. When undertaking overseas projects (such as a commercial complex in Malaysia), Qinglong strictly implements the standards of the International GRC Association and completely avoids the use of chloride-based additives, ensuring structural safety for more than 50 years.

**2. High-Alkali Admixtures: The "Corrodent" of Glass Fibers** The core strength of GRC relies on the interfacial bonding between glass fibers and the cement matrix, while high-alkali (pH>13) admixtures destroy the sizing layer on the glass fiber surface, causing fiber strength loss of more than 30%. Comparative experiments by Qinglong's R&D center found that GRC products using low-alkali admixtures can maintain 90% of their initial long-term flexural strength, far above the industry average.

**3. Admixtures Containing Harmful Volatile Organic Compounds (VOC): A "Double Risk" to the Environment and Health** VOC components contained in some inferior water reducers or defoamers not only cause environmental pollution during production, but may also be released slowly during the building's service stage, affecting indoor air quality. As a national high-tech enterprise, Qinglong always selects environmentally friendly admixtures that comply with the GB 18583 standard, contributing to the achievement of the "green building" goal.

#### III. Qinglong Group's Admixture Application Philosophy: Technological Innovation + Full-Chain Control

From detailed design to after-sales maintenance, Qinglong Group incorporates admixture management into the whole-life-cycle quality control system for GRC. Relying on its provincial-level R&D center and 58 patented technologies, Qinglong has established closed-loop management of "raw materials-formulation-production-testing": on the one hand, through self-developed low-alkali, high-efficiency admixture formulas (such as UHPC-specific water reducers), it has broken through the performance bottlenecks of traditional GRC; on the other hand, it has implemented an "admixture access system" at its production bases in Guangxi and Guangdong, requiring each batch of additives to pass 28 indicator tests including flexural strength and weather resistance, to ensure compatibility with Qinglong's GRC/GRG/GRP products.

**Conclusion**: Admixtures are a "double-edged sword" for GRC material performance; only with scientific understanding as the foundation and standards and specifications as constraints can their true value be fully realized. As a technology leader in the UHPC/GRC/GRG/GRP industry, Qinglong Group always adheres to the values of "integrity, hard work, trust, and collaboration", delivering professional material solutions that bring designers' creative visions to life and safeguard project quality for owners. Choosing compliant, high-quality GRC materials means choosing the safety and enduring beauty of architecture.