Alkalinity Issues and Countermeasures When Using Sulphoaluminate Cement in GRC

In the field of architectural decorative materials, material performance and application details often determine the final quality of a project. As an industry leader with 28 years of deep expertise in UHPC/GRC/GRG/GRP materials, Qinglong Group understands how vital every technical detail is to a project's success. Today, we focus on a key issue in GRC applications—alkalinity control of sulphoaluminate cement in GRC products—to provide professional solutions for designers and owners.

Sulphoaluminate cement is widely used in GRC component production thanks to its rapid hardening, early strength, and excellent impermeability. However, if its inherent high alkalinity is not properly controlled, it can easily cause alkali corrosion of glass fibres, directly affecting the mechanical properties and durability of GRC products. During its participation in drafting the Technical Standard for Building Application of Glass Fibre Reinforced Cement (GRC) (JGJ/T423-2018), Qinglong Group established a scientific alkalinity regulation system validated by thousands of test data points.

I. Core Impact of the Alkalinity Issue in Sulphoaluminate Cement GRC

When the alkalinity of GRC products (pH > 12.5) remains consistently high, an "alkali dissolution" reaction occurs on the glass fibre surface, with fibre strength loss rates reaching 30%-50%. A landmark project once suffered surface cracking of components three years after installation due to uncontrolled alkalinity. Through comparative experiments, Qinglong's technical team found that, under identical curing conditions, GRC specimens with excessive alkalinity showed a 25% drop in 28-day flexural strength compared to standard values, seriously threatening structural safety.

II. Systematic Alkalinity Control Solutions

As a National High-Tech Enterprise, Qinglong Group has integrated 28 years of full-chain experience to form a three-tier prevention and control system:

1. Material-level control: Special low-alkali sulphoaluminate cement (pH controlled at 11-12) is used in combination with self-produced mineral admixtures, so that the slurry alkalinity is stably reduced to a safe range within 7 days. The automated batching system at the Nanning production base can achieve an alkalinity deviation of ≤0.5 pH units.

2. Process-level optimization: The original "gradient curing method" applies 48 hours of controlled-temperature (20-25°C) and controlled-humidity (85%-90%) curing to accelerate the formation of hydration products and promote stable solidification of alkali ions. This process has been granted a national invention patent (patent number omitted).

3. Testing-level assurance: Every batch of products undergoes rapid alkalinity testing with Qinglong's self-developed portable alkalinity meter, which completes testing in just 15 minutes, ensuring that shipped products maintain a pH value stably within the safe range of 9-11.

III. Engineering Practice Validation and Industry Value

In the GRC curtain wall project of the Dongguan Women and Children's Activity Center, Qinglong applied the above technical solution, enabling 5000㎡ of double-curved GRC cladding panels to withstand six years of exposure while maintaining an alkalinity of 10.2±0.3 and a flexural strength retention rate of 92%, winning the AALBORG WHITE Cup GRC Engineering Innovation Award. Compared with traditional processes, this solution extends the service life of GRC products by more than 15 years and reduces life-cycle costs by 20%.

As a member of the International GRC Association, Qinglong Group has always upheld the mission of "Creating Beautiful Architecture," deeply integrating materials science with engineering practice. We recommend that designers, when selecting sulphoaluminate cement GRC, pay close attention to suppliers' alkalinity control technology and full-process quality control capabilities. Only by choosing a professional manufacturer like Qinglong—with integrated capabilities in material R&D, production, and installation—can alkalinity risks be fundamentally avoided, ensuring both the aesthetic effect and structural safety of GRC projects.

Looking ahead, Qinglong will continue to drive technological innovation in GRC materials, building on 28 years of industry experience to provide more reliable material solutions for the global architectural decoration field, fulfilling the vision of "becoming a world-class leading UHPC/GRC/GRG/GRP manufacturing enterprise."