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

The density standard for high-performance GRC curtain walls is ≥2.2g/cm³, with premium products reaching 2.3-2.4g/cm³. This standard originates from the Technical Standard for Building Application of Glass Fiber Reinforced Cement (GRC) (JGJ/T423-2018). Density directly affects core properties such as impermeability, corrosion resistance, and freeze-thaw resistance. Through refined production control, Qinglong has achieved a 100% pass rate for high-performance GRC density, consistently staying above 2.25g/cm³.

1. Core Density Standards and Testing Methods

Clear standards and scientific testing are the foundation for ensuring density. Standard basis: JGJ/T423-2018 stipulates that high-performance GRC density should be ≥2.2g/cm³ with porosity ≤8%; Qinglong products have porosity ≤6%, far exceeding the standard requirements. Testing method: the “volume-mass method” is adopted—standard specimens of 100mm×100mm×100mm are cut, volume and mass are measured, and density is calculated; Qinglong is equipped with high-precision electronic balances (precision 0.01g) and laser rangefinders, with testing error ≤±0.02g/cm³. Sampling rules: 3 specimens are sampled from each production batch (≤50 pieces) for testing, and mass production may only begin after 3 consecutive batches pass; Qinglong's sampling inspection coverage rate reaches 100%, with no unqualified batches.

2. Key Factors Affecting Density

Density is jointly determined by raw materials and multiple production processes. Raw material gradation: aggregates use 0.15-0.6mm continuously graded quartz sand with a bulk density ≥1.6g/cm³; Qinglong's aggregate gradation curve meets optimal packing requirements, increasing density by 10%. Water-cement ratio control: a water-cement ratio ≤0.40 reduces pores formed by excess water evaporation; Qinglong uses polycarboxylate high-range water reducers to keep the water-cement ratio at 0.35-0.38, reducing porosity by 20%. Mixing process: a twin-shaft forced mixer mixes for 5-8 minutes to ensure the raw materials are fully blended without agglomeration; Qinglong strictly controls mixing time at 6 minutes, achieving 98% mixing uniformity. Vibration process: a high-frequency vibrating table (frequency ≥2000 times/min) vibrates for 3-5 minutes, supplemented by immersion vibrators; Qinglong's vibrated specimens show no honeycombing or air bubbles, with uniform density.

3. Qinglong's Density Control Assurance System

Full-process control ensures density consistently meets standards. Production equipment: automated batching system (batching error ≤±0.1%), CNC vibrating table, and steam curing chamber control density at the source; Qinglong's equipment automation rate reaches 90%, minimizing human error. Process inspection: specimen density is tested 24 hours after casting; if it fails to meet standards, the formula and process are adjusted; Qinglong's process inspection pass rate reaches 99%, promptly preventing batch problems. Curing process: steam curing (temperature 20-25℃, humidity ≥90%, curing period ≥7 days) promotes full hydration of cementitious materials, further improving density; Qinglong's density after curing is 5-8% higher than with natural curing. Project case: the GRC curtain wall of the Third-Front Construction Culture and Tourism Project in Panzhihua, Sichuan, achieved a density of 2.3g/cm³ and an impermeability grade of P15, with no leakage or chalking after 10 years of use.