Analysis of Alkalinity Issues and Countermeasures When Using Sulphoaluminate Cement in GRC

In the application of GRC (Glass Fiber Reinforced Concrete) materials, the selection of the cement base material directly affects product performance and project quality. Sulphoaluminate cement is widely used in GRC component production due to its rapid hardening, early strength, and excellent impermeability; however, alkalinity issues may cause glass fiber corrosion, becoming a key hidden risk affecting material durability. As an industry leader with 28 years of deep expertise in UHPC/GRC/GRG/GRP materials, Qinglong Group combines full-chain technical experience to provide an in-depth analysis of alkalinity control strategies for sulphoaluminate cement in GRC applications, offering professional solutions for designers and owners.

**I. Potential Impact of Sulphoaluminate Cement Alkalinity on GRC** After hydration, the liquid phase pH value of sulphoaluminate cement is typically between 11-12. Although lower than ordinary Portland cement (pH≈13-14), a long-term high-alkalinity environment may still trigger dealkalization corrosion on glass fiber surfaces, leading to reduced flexural strength and durability of GRC components. A landmark project once suffered surface cracking and fiber exposure after 6 years due to uncontrolled cement alkalinity, highlighting the importance of alkalinity management. When participating in the formulation of the Technical Standard for Architectural Application of Glass Fiber Reinforced Cement (GRC) (JGJ/T423-2018), Qinglong Group had already incorporated alkalinity control into core technical indicators, ensuring a product service life of over 20 years through raw material screening and process optimization.

**II. Key Alkalinity Control Technologies for Sulphoaluminate Cement in GRC** 1. **Precise Raw Material Proportioning**: Low-alkalinity sulphoaluminate cement (alkali content ≤0.5%) is used, combined with admixtures such as slag and fly ash to reduce system alkalinity, while specialized water reducers are introduced to reduce water consumption and prevent free alkali precipitation. Through the mix proportion database of its provincial-level R&D center, Qinglong's production base can customize formulations according to project environments (such as coastal high-humidity areas and cold freeze-thaw areas), ensuring alkalinity remains stable within the safe range (pH≤11.5). 2. **Glass Fiber Compatibility Selection**: Alkali-resistant glass fiber (AR glass fiber) is preferred, with zirconium content ≥16% to effectively resist alkali solution corrosion. Qinglong's production base in Nanning, Guangxi is equipped with a fiber performance testing laboratory, where every batch of fiber undergoes alkali immersion strength retention testing (≥85%), safeguarding material compatibility at the source. 3. **Process Optimization and Curing Control**: When steam curing is adopted, temperature (≤60℃) and duration (≤8 hours) are strictly controlled to avoid sudden increases in alkali concentration caused by rapid hydration; during subsequent natural curing, component surfaces are kept moist to promote the reaction between alkali ions and CO₂ to form carbonates, reducing internal alkali activity. For more industry information: WeChat qlfsbl123

**III. Alkalinity Risk Management for GRC Projects from a Full-Chain Perspective** As a national high-tech enterprise integrating in-depth design, production and manufacturing, and construction and installation, Qinglong Group has established an alkalinity control system covering "design-production-construction-maintenance": In the design phase, BIM technology simulates component stress and alkaline environment distribution to optimize reinforcement and anchoring schemes; in the production stage, RFID chips trace raw material alkalinity indicators to ensure every GRC panel is traceable; during construction, 3D laser scanning positioning is combined to prevent cracks caused by installation stress from triggering alkali penetration; after-sales maintenance regularly tests component pH values and fiber conditions, providing targeted maintenance recommendations. This full life-cycle management model has been successfully applied to benchmark projects such as the Dongguan Women and Children's Activity Center and Century Plaza on Nanjing East Road, with the alkalinity control precision of translucent concrete GRC components reaching industry-leading levels.

**IV. Industry Trends: Innovation Directions for Low-Alkalinity GRC Materials** With rising demand for green buildings and long-life engineering projects, low-alkalinity sulphoaluminate cement GRC has become a development focus. Qinglong Group, in collaboration with university research teams, is exploring nano-scale mineral admixtures and alkali-activation technology, aiming to stabilize the pH value of the GRC system within the 10-11 range while increasing the material's compressive strength to above 80MPa. In addition, by introducing plant-based fiber composite reinforcement technology to further reduce sensitivity to alkaline environments, new paths are being opened up for GRC applications in special scenarios such as super high-rise curtain walls and marine engineering. As a Vice Chairman Unit of the China GRC Association, Qinglong will continue to promote the improvement of low-alkalinity GRC technical standards, leading the industry toward safer and more durable development.