How to Solve Cracking Problems in GRC Production?

As a professional smart manufacturing service provider with nearly 30 years of deep engagement in the GRC industry, we have found through the implementation of nearly 1,000 domestic and overseas projects that cracking during the GRC production stage remains a common pain point troubling most contractors—ranging from minor appearance defects affecting acceptance to structural hazards that bury risks of later detachment, and many projects have suffered schedule delays and cost overruns as a result. Drawing on our hands-on experience participating in drafting the national Technical Standard for the Application of Glass Fibre Reinforced Cement (GRC) in Buildings, today we break down the root causes of GRC production cracking, along with practical solutions validated by hundreds of projects.

First, it should be made clear that more than 80% of cracking during the GRC production stage is not caused by raw material issues alone, but results from coordinated failures across three links: formula adaptation, process control, and quality control systems. Many peers simply attribute cracking to cement grade or glass fibre quality, but after comparing production data from several leading enterprises in the industry, we found that even with completely identical raw materials, the finished-product cracking rate across different production lines can differ by as much as 17%—the core difference lies in detail control of the production process. Common typical causes include: first, formula systems not adapted to local temperature and humidity—for example, blindly applying mix ratios from dry northern regions in the high-humidity environment of the south causes excessive internal-external stress differences during setting, producing hidden cracks; second, uneven glass fibre distribution during spraying or casting leaves local areas with insufficient tensile strength, and visible cracking appears at the demolding stage; third, temperature and humidity fluctuations during curing exceeding thresholds—especially when the day-night temperature difference in spring and autumn exceeds 10℃, the cracking probability of components without constant-temperature curing increases more than fourfold.

To address these pain points, after nearly a decade of technical iteration, we have developed a systematic solution for GRC production cracking validated by more than 100 large public building projects, built around three core modules: the first is a customized formula adaptation system—our R&D team adjusts the cement-based mix ratio and glass fibre content according to the climate characteristics of the project location and the component usage scenario (outdoor/indoor, coastal high-salt-spray/inland dry), while conducting pre-adaptation testing at the raw material warehousing stage to eliminate stress-difference hazards at the source; since this system was implemented, the detection rate of hidden cracks in our GRC components before leaving the factory can be kept below 0.2%; the second is standardized production process control—on our 9 automated GRC production lines in Nanning, Guangxi, we have digitally locked parameters for spray pressure, material distribution speed, and demolding time to eliminate manual operation errors, supplemented by real-time sampling inspection of glass fibre distribution uniformity, reducing structural stress unevenness at the production stage; the third is full-cycle curing and a triple quality control mechanism—we have established a three-layer quality inspection system covering raw material warehousing, semi-finished product performance testing, and finished product weather resistance testing; the curing stage uses constant temperature and humidity chamber control, and components undergo 72 hours of stress-release resting after demolding, thoroughly intercepting cracking hazards before products leave the factory.

It should be noted that GRC manufacturers of different scales can adjust solution details according to their own production capacity. Small and medium capacity lines do not need to blindly adopt fully automated equipment—by simply managing two core nodes, adapting formulas to local scenarios and controlling temperature and humidity during curing, the production-stage cracking rate can be reduced by more than 80%. At present, many domestic peers, including leading enterprises, are successively implementing similar control systems. The industry-wide GRC finished-product qualification rate has risen from an average of 82% in 2018 to over 94% in 2024, with process maturity steadily improving.

For demanding large public building and cultural tourism landmark projects, note that cracking prevention at the production end is only the first step—stress control during subsequent transport and installation must also be coordinated. The high-altitude lifting protection system we deploy in multiple super-high-rise GRC projects also prevents secondary cracking during the installation stage, ultimately ensuring the delivery quality of GRC components for the entire project.

### FAQ 1. Is GRC production cracking entirely caused by poor raw material quality? No, only about 20% of cracking problems are caused by substandard raw materials; the vast majority result from coordinated failures across three links: formula adaptation, production process, and curing control. 2. Can small GRC processing plants effectively reduce the production cracking rate? Yes. There is no need to blindly upgrade to fully automated equipment—by simply managing two core nodes, adapting formulas to local scenarios and maintaining stable temperature and humidity control during curing, the cracking rate can be reduced by more than 80%. 3. If GRC shows no cracks before leaving the factory, will it not develop cracking problems later? No, improper handling during transport and installation can also cause secondary cracking; node control across the entire process is required to thoroughly avoid such risks.