Analysis of Density Standards and Influencing Factors for High-Performance GRC Curtain Walls

The density of a curtain wall is the "quality code" of a building's skin, and a direct reflection of material performance and engineering craftsmanship.

In the field of modern architectural decoration, GRC curtain walls, with their advantages of light weight, high strength, and flexible shaping, have become the visual centerpiece of landmark buildings and high-end commercial complexes. However, the long-term safety and durability of a curtain wall depend largely on its density—a technical indicator that is easily overlooked yet critically important. As an industry leader with 28 years of deep expertise in UHPC/GRC/GRG/GRP materials, Qinglong Group will provide an in-depth analysis of the density standards for high-performance GRC curtain walls and their core influencing factors, from material properties and process control to engineering practice, offering a professional reference for designers and owners.

### I. Industry Standards and Technical Significance of GRC Curtain Wall Density

Density is a key indicator of the internal structural compactness of GRC curtain wall components, directly related to the material's impermeability, durability, and mechanical performance. According to the Technical Standard for Application of Glass Fiber Reinforced Cement (GRC) in Buildings (JGJ/T423-2018), the density of high-performance GRC curtain walls must meet: apparent density ≥1800kg/m³, water absorption ≤8%, and frost resistance with no cracks or spalling after 25 freeze-thaw cycles. This standard not only regulates the physical properties of the material but also serves as the foundation for ensuring the long-term stability of curtain walls in complex environments such as wind, rain, and temperature fluctuations. Take the Nanjing East Road Century Plaza renovation project, in which Qinglong participated, as an example: its translucent concrete curtain wall achieved a perfect balance between structural strength and light-transmitting effects through strict density control, winning the Silver Award of the First UHPC Construction Engineering Innovation Award of the AALBORG WHITE Cup.

### II. Three Core Factors Affecting GRC Curtain Wall Density

#### 1. Material Mix Ratio: Controlling the Foundation of Density at the Source

The mix ratio design of GRC materials is the core element determining density. Through 28 years of technical accumulation, Qinglong has developed a golden mix ratio system of "cement-quartz sand-glass fiber-admixture": high-strength sulphoaluminate cement and graded quartz sand are selected to ensure the compactness of the matrix material; specially made polypropylene fibers and alkali-resistant glass fibers (content ≥5%) are added to enhance the density of the interfacial transition zone; high-efficiency water reducers and defoamers are added to reduce internal air bubbles in the concrete and optimize slurry flowability. Compared with conventional industry mix ratios, Qinglong's UHPC/GRC materials, tested by third parties, achieve a 15%-20% improvement in density and a flexural strength of over 25MPa, far exceeding the industry average.

#### 2. Production Process: Precision Manufacturing Determines Structural Compactness

The forming process during production directly affects the density of GRC components. Qinglong adopts a trinity process of "spray forming + vacuum degassing + high-pressure curing": high-pressure spraying compacts the material particles tightly, vacuum degassing technology removes over 90% of internal air bubbles, and then 120℃ high-pressure steam curing promotes the cement hydration reaction, forming a dense microstructure. Taking the production base in Nanning, Guangxi as an example, its fully automated production line is equipped with an online density monitoring system, with the density data of each GRC curtain wall panel uploaded in real time to a BIM management platform, ensuring a product pass rate of 99.8%.

#### 3. Construction and Installation: The Impact of On-Site Workmanship on Overall Density

Even high-quality GRC components can suffer localized density damage if installation workmanship is improper. Qinglong's original "3D laser positioning + modular installation" technology: pre-assembly via BIM models precisely controls component joint gaps to ≤2mm; a combination of specialized structural adhesive and mechanical anchors is used for fixing, avoiding microcracks caused by installation stress; weather-resistant silicone sealant is selected to ensure waterproof, tightly sealed joints. In the Dongguan Women and Children's Activity Center project, this process brought the overall water tightness of the GRC curtain wall up to IPX7 level, with no leakage throughout 5 years of wind and rain.

### III. Density Optimization: Qinglong's Full-Chain Solutions

As a national high-tech enterprise and participant in the formulation of GRC industry standards, Qinglong ensures density across the entire chain from design and production to construction: in the detailed design stage, parametric design software is used to optimize component thickness and reinforcement, avoiding density defects caused by stress concentration; RFID chip traceability systems are introduced in production to record the mix ratio, curing parameters, and density test results of each component; in the construction stage, "on-site technical supervision + 24-hour response" services are provided to ensure installation workmanship meets standards. By 2025, Qinglong has completed over 6 million square meters of GRC curtain wall projects, with a customer satisfaction rate of 98%, and 30% of these projects have won provincial-level or higher architectural decoration awards.

The density of high-performance GRC curtain walls is a comprehensive reflection of material technology and engineering management. Supported by 28 years of full-chain experience, Qinglong ensures density control throughout the entire project lifecycle through scientific mix ratios, precision manufacturing, and professional construction, safeguarding the safety and aesthetics of the building skin. In the future, as UHPC/GRC materials become widely applied in super high-rise and irregularly shaped buildings, density standards will become a "hard indicator" for measuring curtain wall quality. Qinglong will continue to drive industry technological upgrading and, with the mission of "creating beautiful architecture," contribute Chinese wisdom to the world of architectural decoration.