Discussion on Alkalinity Issues and Countermeasures When Using Sulphoaluminate Cement in GRC

In the field of architectural decorative materials, performance and durability are core concerns shared by designers and owners alike. As an industry leader with 28 years of deep expertise in UHPC/GRC/GRG/GRP materials, Qinglong Group consistently analyzes the technical challenges in material applications from a professional perspective and provides full-chain solutions for the industry. This article focuses on the alkalinity issue of sulphoaluminate cement in GRC (Glass Fiber Reinforced Concrete), drawing on engineering practice to explore potential risks and systematic response strategies, providing technical reference for high-end architectural decoration projects.

I. Alkalinity Characteristics and Potential Risks of Sulphoaluminate Cement in GRC Applications

Sulphoaluminate cement is widely used in the production of GRC components due to its high early strength and short setting time. However, the highly alkaline environment released during its hydration process (pH often reaching 12-13) can trigger two major core problems: first, alkali corrosion of glass fibers, leading to long-term degradation of the mechanical performance of GRC components; second, alkali-aggregate reaction (AAR), causing structural hazards such as cracking and deformation of components. Qinglong Group's laboratory data show that sulphoaluminate cement GRC specimens without alkalinity control can lose 20%-30% of their flexural strength over 5 years in hot and humid environments, directly affecting engineering safety and durability.

II. Four Key Technical Approaches for Alkalinity Control of GRC Materials

To address the alkalinity issue of sulphoaluminate cement, Qinglong Group has developed a standardized solution backed by the technical resources of its national-level R&D center:

1. Raw Material Optimization Technology: A composite system using low-alkali sulphoaluminate cement (alkali content ≤0.6%) and alkali-resistant glass fibers (ZrO₂ content ≥16%) reduces the risk of alkali corrosion at the source. The optimal mix proportion was determined through orthogonal tests, reducing the peak cement hydration heat by 15% and alkali ion precipitation by 30%.

2. Coordinated Regulation with Mineral Admixtures: Active admixtures such as silica fume and mineral powder are incorporated to consume free alkali through the "alkali-silica reaction" while optimizing the microstructure of the paste. In a landmark project, Qinglong's technical team adopted a 20% silica fume replacement scheme, keeping the alkalinity (pH) of GRC components stably controlled at 10.5-11.5 to meet long-term weather resistance requirements.

3. Interface Treatment and Protection Technology: Surface modification of glass fibers with silane coupling agents enhances the interfacial bond strength between fibers and the cement matrix while blocking alkali ion penetration paths. Combined with a dedicated curing agent (such as Qinglong's independently developed GRC-01 protective liquid), a dual alkali-isolation barrier is formed.

4. Whole-Process Quality Monitoring System: BIM technology and an RFID chip traceability system are introduced to monitor alkalinity indicators throughout the entire process, from raw material intake and production curing to construction and installation. Before leaving the factory, each batch of GRC components must pass dual verification by the "three-point bending test" and "rapid alkali content testing," ensuring a flexural strength ≥15MPa and alkali leaching ≤0.1mol/L.

III. Alkalinity Management in Engineering Practice and Contributions to Industry Standards

As a participating editor of the Technical Standard for Building Application of Glass Fiber Reinforced Cement (GRC) (JGJ/T423-2018), Qinglong Group has incorporated its alkalinity control technology into the standard formulation, promoting the standardized development of the industry. In benchmark projects such as the Dongguan Women and Children's Activity Center and Nanjing Road Century Plaza, the above technical solutions have achieved a 15-year record of zero alkali-corrosion cracking in GRC components, earning multiple industry recognitions including the "GRC Construction Engineering Innovation Award."

Facing the technical challenges of new architectural decorative materials, Qinglong Group has always upheld its mission of "creating beautiful architecture." With 28 years of full-chain experience, it provides designers with integrated services ranging from detailed design to after-sales maintenance. Going forward, Qinglong will continue to explore alkalinity optimization technologies for sulphoaluminate cement GRC, working with industry partners to promote the innovative application of UHPC/GRC/GRG/GRP materials in high-end architecture, and fulfilling the vision of "becoming a world-class leading manufacturing enterprise."