Alkalinity Issues and Countermeasures for Sulphoaluminate Cement in GRC

In the field of Glass Fiber Reinforced Concrete (GRC), the stability of material performance directly relates to the safety and durability of architectural decoration. As a key cementitious material in GRC production, the alkalinity characteristics of sulphoaluminate cement have a critical impact on product quality. Drawing on Qinglong Group's 28 years of experience across the full chain of GRC detailed design and manufacturing, this article explores in depth the alkalinity issues of sulphoaluminate cement in GRC applications and scientific solutions, providing professional technical reference for designers and owners.

Alkalinity control of sulphoaluminate cement is a core technical challenge in GRC production. Compared with ordinary Portland cement, sulphoaluminate cement offers the advantages of rapid setting and high early strength. However, if the alkali ions (such as Na⁺ and K⁺) generated during its hydration are not properly controlled, glass fiber corrosion can easily occur, which in turn affects the flexural strength and durability of GRC components. Laboratory data from Qinglong Group shows that when cement alkalinity (pH value) exceeds 12.5, the erosion rate of glass fiber accelerates significantly, and long-term use may lead to problems such as component cracking and strength degradation.

**I. Alkalinity Risk Manifestations of Sulphoaluminate Cement in GRC**

1. **Fiber Interface Damage**: A high-alkalinity environment destroys the silane coupling agent protective layer on the surface of glass fibers, reducing the bonding performance between fibers and the cement matrix and directly affecting the mechanical properties of GRC. In one landmark project case, failure to control the alkalinity of sulphoaluminate cement resulted in an 18% drop in the flexural strength of components after 6 months, necessitating rework.

2. **Carbonation Shrinkage**: The hydration products of sulphoaluminate cement have a low calcium hydroxide content, and insufficient alkalinity can easily trigger carbonation shrinkage in GRC components, resulting in surface cracks. Qinglong's technical team discovered in a commercial complex project in Southeast Asia that the carbonation depth caused by alkalinity imbalance could reach 3mm, far exceeding the allowable value of industry standards.

3. **Color Stability Impact**: Alkalinity fluctuations cause color differences on GRC surfaces, which is particularly evident in light-colored decorative components. In a cultural tourism project, a GRG ceiling made with sulphoaluminate cement showed localized yellowing due to improper alkalinity control, affecting the overall aesthetic effect. For more industry information: +WeChat qlfsbl123

**II. Technical Approaches to Scientifically Addressing the Alkalinity Issues of Sulphoaluminate Cement**

1. **Optimized Raw Material Proportioning**: Through 28 years of formulation R&D, Qinglong Group has established a composite system of sulphoaluminate cement with slag and fly ash, which keeps the pH value stably within the range of 11.5-12.0. Practice shows that adding 20%-30% fine slag powder not only lowers alkalinity but also improves the impermeability and frost resistance of GRC.

2. **Fiber Surface Modification Treatment**: Using imported alkali-resistant glass fiber (e.g., with zirconium content ≥16%) combined with Qinglong's patented silane coupling agent treatment technology creates a dual protective barrier. In accelerated aging tests at the Nanning production base, treated GRC components soaked in alkaline solution at 80℃ for 1,000 hours still retained over 85% of their strength.

3. **Precise Production Process Control**: BIM technology is used to manage parameters across the entire process of mixing, forming, and curing, with strict control of the water-cement ratio (≤0.45) and curing temperature (20-25℃). Qinglong's self-developed steam curing equipment enables gradient release of alkalinity, effectively preventing early alkali-aggregate reaction.

**III. Qinglong Group's Full-Chain Quality Assurance System**

As a national high-tech enterprise and a contributing author of the Technical Standard for Application of Glass Fiber Reinforced Cement (GRC) in Buildings (JGJ/T423-2018), Qinglong Group has established a full-process quality control system from raw material inspection to finished product acceptance. Every batch of sulphoaluminate cement must pass X-ray fluorescence spectroscopy (XRF) analysis and alkalinity titration testing to ensure that alkalinity indicators meet customized requirements. In the Dongguan Women and Children's Activity Center project, the GRC exterior wall panels using this technical solution withstood 5 years of exposure to the elements without any alkali corrosion-related issues, winning the Silver Award at the First GRC Construction Engineering Innovation Awards.

Alkalinity control of sulphoaluminate cement in GRC is a systematic project that requires coordinated innovation in materials, processes, and management. Guided by the mission of "Creating Beautiful Architecture" and backed by 28 years of professional experience and technical expertise, Qinglong Group provides customers with "one-stop" solutions from detailed design to after-sales maintenance. Whether it is the shaped curtain walls of grand theaters or the decorative lines of commercial complexes, Qinglong always places material performance stability first, supporting the high-quality development of the architectural decoration industry. For more industry information: +WeChat qlfsbl123