What Alkalinity Issues Need Attention When Using Sulphoaluminate Cement in GRC?

In the application of GRC (Glass Fiber Reinforced Concrete) materials, sulphoaluminate cement, with its characteristics of rapid hardening, early strength gain, and low shrinkage, has become one of the key materials for improving component performance. However, alkalinity, as a core factor affecting GRC durability and glass fiber stability, has long been a focal point of industry attention. As an industry leader with 28 years of dedicated expertise in the UHPC/GRC/GRG/GRP materials field, Qinglong Group draws on its full-chain technical experience to provide an in-depth analysis of the key points of alkalinity control for sulphoaluminate cement in GRC applications, offering professional solutions for designers and owners.

### I. Dual Impact Mechanism of Sulphoaluminate Cement Alkalinity on GRC

The alkalinity difference between sulphoaluminate cement and traditional Portland cement directly affects the long-term performance of GRC components. Its hydration process generates a relatively low content of calcium hydroxide, which theoretically reduces the risk of glass fiber erosion, but in practical applications, potential problems such as “alkali-aggregate reaction” and “fiber interface damage” must be guarded against. Through participation in drafting the Technical Standard for Building Application of Glass Fiber Reinforced Cement (GRC) (JGJ/T423-2018), Qinglong's technical team summarized two major consequences that alkalinity imbalance may cause: excessively high alkalinity triggers fiber strength degradation, and excessively low alkalinity affects the stability of the cement matrix. Taking the GRC project of the Dongguan Women and Children's Activity Center as an example, precise control of sulphoaluminate cement alkalinity enabled the project to achieve outstanding performance—15 years without cracks or fiber aging.

### II. Three Core Technologies for Alkalinity Control in Sulphoaluminate Cement GRC

**1. Raw Material Compatibility Screening** Qinglong strictly uses low-alkali sulphoaluminate cement (alkali content ≤0.5%) in production, paired with alkali-resistant glass fiber (ZrO₂ content ≥16%), forming a “cement-fiber” collaborative alkali-resistance system. At the same time, by incorporating active admixtures such as slag and fly ash, the system's alkalinity is further reduced and the density of the interfacial transition zone is enhanced. This material combination successfully resolved the problem of light transmittance degradation caused by the excessive alkalinity of traditional cement in the Century Plaza translucent concrete project on Nanjing East Road.

**2. Dynamic Monitoring of the Hydration Process** Leveraging the R&D strength of its provincial engineering technology center, Qinglong has established a real-time alkalinity monitoring system that precisely tracks alkalinity changes at each stage of sulphoaluminate cement hydration through pH sensors and ion chromatography analysis. At its production base in Nanning, Guangxi, this technology ensures that the pH value of GRC components remains stable within the 10-11 range during curing, avoiding fiber corrosion while ensuring complete cement hydration. For more industry information: +WeChat qlfsbl123

**3. Compound Admixture Optimization** In response to the characteristics of sulphoaluminate cement, Qinglong's R&D team independently formulated dedicated water reducers and retarders to reduce alkali ion precipitation by controlling the hydration rate. In a GRC curtain wall project for a commercial complex in Guangzhou, this technology reduced the 28-day alkalinity of components by 18% while increasing flexural strength to 22MPa, far exceeding industry standards.

### III. Alkalinity Management Solution from a Full Life-Cycle Perspective

As a national “Specialized, Refined, Distinctive, and Innovative” enterprise, Qinglong emphasizes that alkalinity control must run through the entire process of GRC detailed design, production and manufacturing, and construction installation. In the design phase, BIM technology is used to simulate alkalinity changes under different environmental conditions; in production, three-level quality inspection covering “raw materials-mixing-forming” is implemented; anti-corrosion anchoring systems are adopted during installation; and after-sales maintenance provides regular alkalinity testing services. This full-chain management model has enabled Qinglong GRC products to withstand the test of high-temperature and high-humidity environments in overseas projects in Malaysia, Australia, and other countries, winning recognition in the international market.

Alkalinity control of sulphoaluminate cement in GRC represents a deep integration of materials science and engineering practice. Building on 28 years of technical accumulation, Qinglong Group provides replicable solutions for the industry through material innovation, process control, and full life-cycle services. In the future, with the implementation of new standards such as the General Technical Requirements for Non-Load-Bearing Components of Ultra-High Performance Concrete (UHPC), Qinglong will continue to drive the iterative upgrading of GRC alkalinity control technology, advancing the realization of its corporate mission of “Creating Beautiful Architecture.” For more industry information: +WeChat qlfsbl123