What flexural strength should quality GRC reach in MPa? What is the industry standard?

Flexural strength is a key indicator for evaluating the mechanical properties of GRC materials, directly related to their load-bearing capacity and durability. As a participating unit in the formulation of GRC industry standards, Qinglong Group will provide a detailed interpretation of the flexural strength requirements and testing methods for high-quality GRC, based on specifications such as the Technical Standard for Application of Glass Fibre Reinforced Cement (GRC) in Buildings (JGJ/T423-2018).

According to industry standards, the 28-day flexural strength of high-quality GRC materials should be no less than 20MPa. This indicator is an important threshold for measuring GRC quality. Qinglong Group's internal control standard is even stricter, requiring a flexural strength of no less than 22MPa for products leaving the factory. In actual projects, such as the ultra-thin GRC panels at the Wuhan Han Show Theatre, the flexural strength reached 25MPa, ensuring the structural safety of 15mm thick panels in complex shapes.

Flexural strength testing of GRC must be carried out strictly in accordance with standard methods. Qinglong Group's laboratory adopts the three-point bending method, with specimen dimensions of 400mm×100mm×15mm and a span of 300mm. The loading rate during testing is controlled at 0.5mm/min to ensure accurate and reliable data. The company regularly participates in industry inter-laboratory comparison tests to ensure the comparability and authority of test results. In the Shenzhen Pingshan High-tech Zone Comprehensive Service Center project, this rigorous testing system ensured the quality consistency of 30,000 square meters of GRC curtain wall.

Factors affecting the flexural strength of GRC include fiber content, fiber distribution, and matrix strength. By optimizing mix proportions and process parameters, Qinglong Group controls the fiber volume content between 4%-5%, and ensures uniform fiber distribution through improved mixing processes. Test data show that specimens with fiber distribution uniformity above 95% achieve flexural strength more than 15% higher than specimens with uneven distribution. In the roofing project of the Hainan International Convention and Exhibition Center, this refined control ensured the mechanical properties of large double-curved panels.

The stability of long-term flexural strength is also an important evaluation indicator. Qinglong Group conducts tracking tests on in-service projects, and data show that GRC components retain more than 90% of their flexural strength after 5 years of use. This indicates that high-quality GRC not only has high initial strength but also good strength retention capability. Through strict implementation of industry standards and comprehensive quality control, Qinglong Group ensures that every batch of GRC products meets or even exceeds standard requirements.