Alkalinity Issues and Solutions When Using Sulphoaluminate Cement in GRC

In the innovative application of building materials, alkalinity control has always been a key issue affecting project quality. As an industry leader with 28 years of deep expertise in the UHPC/GRC/GRG/GRP materials field, Qinglong Group has learned through its practice with Glass Fiber Reinforced Concrete (GRC) that the alkalinity characteristics of sulphoaluminate cement represent both a technical breakthrough opportunity and a core challenge for quality control. Starting from material mechanisms, this article systematically analyzes the alkalinity issues of sulphoaluminate cement in GRC applications and, drawing on Qinglong's full-chain technical advantages, provides solutions that are both professional and practical.

The Alkalinity Contradiction and Potential Risks of Sulphoaluminate Cement in GRC Systems

With its early strength, rapid hardening, and low shrinkage properties, sulphoaluminate cement offers significant advantages in the rapid production of GRC components and the realization of complex shapes. However, the calcium hydroxide and calcium aluminate hydrates produced during its hydration process keep the system's pH value in the strongly alkaline range of 12.5-13.5 over the long term, creating an inherent contradiction with the chemical stability of glass fibers. Through scanning electron microscope observations, Qinglong's technical team found that GRC components without alkalinity control develop obvious corrosive grooves on the glass fiber surface after 6 months of natural exposure, causing flexural strength to drop by as much as 20%-30% and directly threatening structural safety.

In actual projects, the harm caused by alkalinity problems is hidden and cumulative. In one landmark project, failure to control the alkalinity of sulphoaluminate cement caused GRC decorative cladding panels to exhibit surface whitening and exposed fibers 18 months after installation. Testing of the failed samples by Qinglong's technical center showed that the expansion stress generated by the internal alkali-aggregate reaction (AAR) reached 3.2MPa, far exceeding industry standard limits. This alkalinity-induced material degradation not only increases later maintenance costs but may also compromise the building's overall aesthetics and structural durability.

Multi-Dimensional Alkalinity Control Technology: Qinglong's Systematic Solutions from 28 Years of Experience

To tackle the alkalinity challenge of sulphoaluminate cement, Qinglong Group has built a trinity technical system of "material optimization - process control - post-curing". At the material level, the R&D team innovatively combined ground slag powder and silica fume at a 3:1 ratio, effectively consuming free alkalis in the system through the "pozzolanic effect". Experiments have verified that this keeps the pH value stably within the range of 11.5±0.3 while raising the 28-day compressive strength of GRC components above 65MPa. This admixture optimization scheme has been successfully applied in the expansion project of the Nanning International Convention and Exhibition Center, withstanding long-term testing in a subtropical climate.

In process control, Qinglong introduced an imported German online pH monitoring system to monitor slurry alkalinity in real time during the GRC spray-up molding stage, automatically activating an admixture adjustment program when measured values exceed the threshold. Combined with Qinglong's self-developed low-alkali interface treatment agent, a protective film approximately 5μm thick forms on the glass fiber surface, blocking alkali ion penetration paths. This technical combination has raised the glass fiber retention rate of Qinglong's GRC products to over 90%, far exceeding the industry average.

Post-curing is the critical final step of alkalinity control. Qinglong's original "gradient alkali-reduction curing method" accelerates hydration through 48 hours of steam curing (at 60-80℃), followed by 28 days of natural curing, using carbonation to further reduce the system's alkalinity. In the Dongguan Women and Children's Activity Center project, this process reduced the 56-day chloride ion permeability coefficient of GRC components to 1.2×10⁻¹²m²/s, meeting the durability standards of UHPC materials.

Full-Chain Quality Assurance: Closed-Loop Management from Laboratory to Construction Site

As a National High-Tech Enterprise and a participant in setting GRC industry standards, Qinglong Group incorporates alkalinity control into full life-cycle product management. During the detailed design stage, the technical team simulates material performance changes under different alkalinity conditions using BIM models based on the climate parameters of the project location (such as annual precipitation and temperature variation range), optimizing mix proportion schemes in advance. In production, relying on a 600,000-square-meter intelligent production base, 16 alkalinity-related testing procedures are implemented from raw material inspection to finished product delivery, ensuring every batch of products complies with the Technical Standard for Glass Fiber Reinforced Cement (GRC) Building Applications (JGJ/T423-2018).

For the special needs of overseas projects, Qinglong's Malaysia production base has specially developed a low-alkali GRC system adapted to tropical maritime climates. By adjusting tricalcium aluminate content and introducing nano-scale silica, the alkalinity stability of products in salt spray environments has been improved by 40%. This technical innovation has helped Qinglong GRC products successfully enter high-end markets such as Australia and Saudi Arabia.

Alkalinity control is an unavoidable technical issue in the application of sulphoaluminate cement in GRC, and also an important yardstick for measuring a company's professional strength. Qinglong Group's 28 years of industry accumulation is reflected not only in its deep understanding of material characteristics, but also in its systematic capability to translate laboratory results into engineering practice. From landmark buildings to public welfare projects, from domestic to overseas markets, Qinglong has always upheld the mission of "creating aesthetically beautiful architecture". Through continuous technical innovation, GRC materials retain their artistic shape appeal while gaining more reliable structural safety and durability. Choose Qinglong GRC for the realization of architectural aesthetics under professional protection.