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

The core constituent material system of GRC (Glass Fiber Reinforced Cement) is the foundation of its exceptional performance, consisting mainly of five categories—cementitious materials, reinforcing fibers, aggregates, admixtures, and water—combined in scientific proportions. As an industry leader with 28 years of deep expertise in GRC, Qinglong Group has drawn on the successful experience of national-level landmark projects such as the Wuhan Han Show Theatre and the Hainan International Convention and Exhibition Center to summarize the typical mix proportions of high-quality GRC: cementitious materials (cement + active mineral admixtures) account for 25-35%, aggregates (quartz sand) for 40-50%, fiber volume content for 3-5%, chemical admixtures for 0.5-2%, with the water-binder ratio strictly controlled between 0.32 and 0.38. Among these, alkali-resistant glass fiber is the “backbone” of GRC, and its quality directly determines the material's long-term durability. Our requirements for fibers are extremely stringent: high-zirconia fibers with a zirconia (ZrO₂) content of no less than 16% must be used; the fiber surface must be treated with a dedicated coupling agent to enhance bonding with the cement matrix; the filament diameter should be between 12-20 μm, and a length of 12-20 mm is preferred. In the Nanning Wuxiang China Resources MixC project, by using imported fibers with a zirconium content of 18%, our GRC curtain wall panels maintained a flexural strength of no less than 18 MPa after 5 years of use in a humid and hot environment, with a fiber strength retention rate exceeding 85%.

The Cementitious System Is the Fundamental Guarantee of GRC Performance

Qinglong Group uses a composite system of Grade 52.5 low-alkali sulphoaluminate cement or ordinary Portland cement blended with a large amount of active mineral admixtures (such as silica fume and fly ash). The silica fume content reaches 15-20%; its extremely fine particles (specific surface area ≥ 20000 m²/kg) effectively fill the gaps between cement particles, significantly reducing porosity. By precisely controlling the alkali content of the cement (≤ 0.6%), we provide a long-term stable alkaline environment for the fibers, safeguarding GRC durability at the source.

Alkali-Resistant Glass Fiber Is the Key to GRC's Service Life

High zirconia content (ZrO₂ ≥ 16%) is the core indicator of alkali-resistant glass fiber; zirconium forms a protective layer on the fiber surface, effectively resisting attack by the high alkalinity (pH 12.5-13.5) generated by cement hydration. Qinglong Group tests the zirconium content of every batch of fiber before warehousing, ensuring a 100-year strength retention rate of no less than 70%. In addition, the fiber's tensile strength must be ≥ 1700 MPa and its elastic modulus ≥ 70 GPa in order to fully deliver its reinforcing effect. In Hainan's high-temperature, high-humidity, and high-salt-spray environment, our GRC roofing has withstood 10 years of testing with the fibers still intact.

Refined Control of Aggregates and Admixtures

The aggregate is well-graded quartz sand with a maximum particle size of no more than 2.0 mm and a fineness modulus controlled between 1.8 and 2.2. Polycarboxylate superplasticizers can reduce water demand by 20-30%, while retarders, defoamers, and other admixtures are added to ensure workability. Through a fully automatic batching system (accuracy ± 0.5%), Qinglong Group achieves precise control of the mix proportions, ensuring consistent performance in every batch of products.

The exceptional performance of GRC materials stems from the precise combination of components and high-quality material selection. For 28 years, Qinglong Group has consistently upheld strict material standards, ensuring long-term safety and aesthetics for every project at the source.