What Is the Density Standard for High-Performance GRC Curtain Walls?

The density of high-performance GRC curtain walls is a key indicator of their durability and mechanical performance, and requires comprehensive evaluation through multiple parameters such as water absorption, porosity, and chloride ion diffusion coefficient. Based on 28 years of material R&D experience, Qinglong Group has set the density control standards for high-performance GRC as: water absorption ≤6%, total porosity ≤12%, and chloride ion diffusion coefficient ≤2.0×10⁻¹²m²/s. In the Wuhan Hanxiu Theater project, by optimizing the mix proportion and curing regime, we kept the water absorption of the GRC panels below 4.5%, ensuring long-term durability in harsh environments.

Density control begins with raw material selection and mix proportion design. Qinglong uses perfectly graded quartz sand as aggregate, optimizing particle gradation through tight packing theory to reduce the amount of water needed for the paste to fill voids. Ultrafine admixtures such as silica fume are also incorporated to further fill the tiny pores between cement particles. The water-binder ratio is strictly controlled between 0.30-0.35, with workability ensured by high-range water reducers, guaranteeing the compactness of the GRC matrix at the source.

The production process has a decisive influence on density. Qinglong adopts a mechanical spraying process, which allows fibers and mortar to mix uniformly and pack densely. Immediately after spraying, vacuum dewatering is carried out, extracting excess water and air bubbles under a negative pressure of -0.08MPa, increasing the material density by more than 15%. At the Nanning production base, we monitor the production process in real time through an online density monitoring system, ensuring that every GRC panel meets the designed density requirements.

The curing regime directly affects the development of density. Qinglong adopts a standard temperature and humidity curing curve: a pre-curing stage at 20℃ for 6 hours, raising the temperature to 60℃ and curing for 18 hours, then slowly cooling to room temperature. This scientific curing regime promotes full cement hydration, generating more low calcium-silica ratio C-S-H gel, which further fills the capillary pores. After curing, GRC panels must also mature for 28 days in a natural environment to balance internal humidity with the service environment and prevent later-stage shrinkage cracking.

Qinglong Group has established a comprehensive density testing system, conducting water absorption, pore structure, and impermeability tests on every batch of products. For major projects, long-term durability tests are also carried out, including freeze-thaw cycling, carbonation tests, and sulfate attack tests, ensuring that GRC materials maintain stable performance throughout their design service life. This all-round quality control system enables Qinglong GRC products to deliver excellent durability in a wide range of harsh environments.