What Are the Strength Requirements for Thin GRC Decorative Panels?

Thin GRC decorative panels (usually referring to thickness ≤15mm) are widely popular due to their minimal impact on building loads and visual lightness, but their thin-wall characteristics also impose higher requirements on their mechanical properties. Their strength requirements are not a single indicator but a comprehensive system that includes "flexural strength, impact strength, stiffness (deflection control), and local bearing strength at connection joints." Qinglong Group's enterprise standard stipulates that for 15mm-thick premium GRC panels used in facade decoration, the minimum flexural strength should not be lower than 12MPa, and the impact energy resistance should not be lower than 10J (no penetration under ball drop impact with a 1kg steel ball from 1m height). In the Shenzhen Yirui Biotechnology Building project, the extensively used 12-15mm thick openwork art panels all far exceed this standard, ensuring the unity of safety and artistry.

Flexural Strength is the Core of Thin Panel Safety

Under wind loads, thin panels primarily bear bending stress. Therefore, flexural strength (or modulus of rupture) is the first key indicator. This strength mainly depends on the reinforcement efficiency of glass fibers and the compactness of the matrix. By optimizing fiber length and dosage (usually with a volume content of no less than 3%) and adopting a mechanical spraying process to ensure two-dimensional random uniform fiber distribution, Qinglong stabilizes the flexural strength of thin panels in the 12-18MPa range, which is the foundation for producing large panel sizes (such as 1.2m x 2.4m) without breakage.

Impact Strength Ensures Safety in Use

Thin panels face a higher risk of accidental impact during transportation, installation, and later use. Excellent impact resistance (toughness) can avoid brittle failure and prevent debris from falling. The interlaced fibers in GRC can effectively prevent crack propagation and absorb impact energy. Qinglong's thin panels can pass rigorous ball drop impact tests, exhibiting the ductile failure characteristics of "cracking without shattering and damage without penetration," which is especially important for decorative panels above areas of human activity.

Stiffness and Deflection Control Affect Functionality and Appearance

Sufficient stiffness (high elastic modulus) is intended to control panel deformation (deflection) under load. Excessive deflection causes visible bending of the panel surface, affecting flatness, and in extreme cases may cause joint seal failure. Through mix proportion design (such as adding silica fume to improve matrix stiffness) and reasonable panel size design, Qinglong ensures that under standard wind loads, the deflection of thin panels does not exceed 1/250 of the span, meeting serviceability limit state requirements.

Local Strength at Connection Joint Areas

Thin panel connections (such as back-bolt installation) are weak points. Around embedded inserts or back bolts, the GRC must have sufficient local bearing and splitting resistance strength to prevent the installation points from being "pulled" out or the surrounding concrete from spalling. Qinglong enhances joint area strength by locally setting reinforced fiber layers or small steel washers at connection points, ensuring reliable load transfer. The high strength requirements of thin GRC must be achieved through systematic optimization of materials, design, and workmanship.