What Are the Core Constituent Materials of GRC? What Are the Requirements for Alkali-Resistant Glass Fiber?

As a high-performance composite material, GRC (Glass Fiber Reinforced Concrete) derives its outstanding performance from the synergy between the cement matrix and alkali-resistant glass fibers. As Qinglong Group, with 28 years of experience in GRC R&D and manufacturing, we have summarized the core composition of GRC into four major systems: "cementitious materials, reinforcing fibers, aggregate systems, and functional additives." In the "Chinese Red Lantern" curtain wall project of the Hanxiu Theater in Wuhan, we enabled GRC panels to maintain excellent mechanical performance even under a thin-wall condition of 15mm through precise material proportioning control, fully demonstrating the importance of scientific proportioning. The performance of GRC materials depends 30% on design and 70% on materials.

Scientific Selection of the Cementitious Material System

The cementitious materials for GRC typically use sulphoaluminate cement or low-alkalinity Portland cement, with alkalinity (pH value) controlled below 11.5 to protect glass fibers from strong alkali attack. For the 120,000-square-meter roofing project of the Hainan International Convention and Exhibition Center, Qinglong specially selected high-grade sulphoaluminate cement to ensure the long-term durability of GRC in a marine climate. Cement content is generally controlled at 350-450kg/m³, which ensures strength while avoiding excessive shrinkage.

Key Technical Requirements for Alkali-Resistant Glass Fibers

Alkali-resistant glass fiber is the soul of GRC, and its quality directly determines the service life of the material. Qinglong strictly implements the highest industry standards, requiring the zirconia (ZrO₂) content in glass fibers to be no less than 16.5%—the key component for resisting cement alkalinity. Fiber length is typically 12-36mm with a diameter of 12-20μm, and fiber content is adjusted between 3%-5% according to the load-bearing requirements of components. In the woven texture curtain wall project of the Dongguan Women and Children's Activity Center, we ensured the crack resistance of complexly shaped areas by optimizing fiber distribution.

Gradation Optimization of the Aggregate System

GRC aggregates are mainly refined quartz sand, with a maximum particle size not exceeding 1.2mm. Qinglong adopts a multi-graded sand system, mixing coarse sand (0.6-1.2mm) and fine sand (0.1-0.3mm) in specific proportions to improve density while ensuring slurry flowability. For GRC with special effects, we incorporate colored aggregates or functional aggregates, such as adding natural stone powder to stone-imitation GRC to enhance textural realism.

Precise Application of Functional Additives

Admixtures are the "seasoning masters" of GRC performance. Qinglong uses polycarboxylate high-range water reducers to lower the water-binder ratio, incorporates shrinkage-reducing agents to control drying shrinkage, and adds thickeners, defoamers, and others as needed. All admixtures undergo rigorous compatibility testing to ensure they work synergistically with cement and fibers. Scientific material proportioning is the fundamental guarantee of GRC's outstanding performance.