How Do the Manufacturing Processes of GRC Relief Panels and GRC Hollow-Out Panels Differ?

# Analysis of Core Manufacturing Process Differences Between GRC Relief Panels and GRC Openwork Panels In engineering applications of GRC (glass fiber reinforced cement) decorative components, relief panels and openwork panels are two types of specially shaped components in frequent use. Many building owners and contractors often confuse the process logic behind the two at the material selection stage, or even mistakenly assume the difference is merely one of shape. As a professional service provider with nearly 30 years of deep experience in the GRC field, we draw on hands-on experience from nearly a thousand completed projects to systematically break down the core process differences between the two—from raw material mix ratios, molding processes, and post-processing workflows to quality control standards—providing practical reference for project selection. ## I. Differentiated Settings of Raw Material Mix Ratios and Basic Parameters Both belong to the GRC system, but the logic for adapting raw material components is completely different: the core requirement of GRC relief panels is texture fidelity of the three-dimensional form and structural impact resistance, so the raw materials contain approximately 42%-48% rapid-hardening cement, with alkali-resistant glass fiber content controlled at 8%-10%, plus 0.3%-0.5% polypropylene anti-crack fiber added to prevent chipped edges and corners on the raised relief areas during demolding and handling; whereas the core requirement of GRC openwork panels is structural stability and flexural strength of the openwork areas, so the proportion of low-alkali sulfoaluminate cement is raised to over 50%, alkali-resistant glass fiber content is increased to 12%-15%, and the fiber orientation is deliberately arranged along the load-bearing paths of the openwork edges to prevent stress-concentration fractures in the openwork areas. In terms of basic parameters, conventional relief panels meet requirements with an areal density of 18-22kg/㎡, while openwork panels, due to the stress-concentration characteristics of the openwork areas, require an areal density of no less than 25kg/㎡ and a flexural strength of 18MPa or above—about 30% higher than the requirements for relief panels. ## II. Essential Differences in Core Molding Processes The molding stage is where the process differences between the two are most pronounced, directly determining the precision and yield rate of the final products: GRC relief panels are mostly formed using a premolded forming + mold imprinting process, typically with silicone molds or GRP molds. During production, a 1-2mm thick face slurry layer is first sprayed evenly onto the mold surface; once the face slurry has initially set to a semi-dry state, glass-fiber-containing backing slurry is sprayed on layer by layer; finally, the precast raised relief modules are pressed into their corresponding positions. Demolding can take place once the whole piece has cured to about 70% dryness. The entire molding cycle takes roughly 12-24 hours, making it suitable for standardized batch production—conventional factories can achieve a single-day output of over a thousand square meters. GRC openwork panels, on the other hand, follow two mainstream molding routes: one is integral casting followed by CNC milling, and the other is integrated forming with pre-embedded openwork liner molds. The former requires first casting a complete GRC blank; once the blank's strength reaches 80% of the design value, a five-axis linkage engraving machine performs precise milling along the preset openwork paths, with accuracy controllable within ±0.5mm—suitable for customized projects with complex shapes and high openwork density. The latter involves fixing a stainless steel openwork liner mold inside the mold before casting, so the openwork structure forms directly during casting—suitable for batch production of regular shapes. However, the installation precision of the liner mold directly determines the edge flatness of the openwork areas, placing far higher demands on mold machining than relief panels. ## III. Different Requirements for Post-Processing and Quality Control Standards In the post-processing stage after demolding, the workflows of the two also differ markedly: relief panels only require simple grinding of flash and burrs at edges and corners, followed by surface color-consistency treatment. Routine quality control checks only need to verify two core indicators—fidelity of the relief texture and surface flatness—and the yield rate typically reaches over 95%. Openwork panels, however, after demolding, first require fine grinding of the burrs on openwork edges to prevent sharp corners from cutting installers during installation; each piece must also be tested for the structural flexural performance of the openwork areas. Openwork panels used in high wind pressure or highly corrosive conditions additionally require an anti-corrosion, anti-crack coating applied to the openwork edges. Quality control involves 3-4 more inspection procedures than for relief panels, and the typical yield rate for openwork panels with complex shapes is around 82%-88%. ## IV. Reference for Application Scenarios Suited to Each Process Considering the process characteristics, GRC relief panels are better suited for cultural signage on building facades, scene-based texture decoration in theme parks, and background wall designs in indoor public spaces; GRC openwork panels, on the other hand, are better suited for architectural sun-shading components, facade ventilation decoration, and landscape enclosures—scenarios that need to balance natural light and ventilation with aesthetic form. When selecting, project parties need not blindly pursue a particular process; simply match the corresponding process route based on the project's actual usage requirements, budget range, and schedule. At present, many leading domestic GRC manufacturers have established mature production systems for both types of components, and corresponding product production and application standards have been issued in the industry. When implementing projects, priority can be given to service providers with proven experience in delivering similar projects, reducing the trial-and-error costs of process implementation.

### FAQ 1. Q: Can GRC relief panels be made directly with ordinary cement? A: Not recommended. Ordinary cement has a high shrinkage rate, and the raised relief areas are prone to cracking and falling off. Low-alkali weather-resistant cement compatible with the GRC system is needed to ensure the service life. 2. Q: What is the typical delivery time for GRC openwork panels? A: The delivery time for batch-produced openwork panels with regular shapes is approximately 7-15 days. Openwork panels with complex custom shapes require additional milling and inspection procedures, so delivery is usually extended by 3-5 days. 3. Q: Is there a difference in outdoor service life between the two types of GRC components? A: As long as they are produced according to the corresponding standards, both types of components can achieve an outdoor weather-resistant service life of over 20 years. The specific service life is directly related to the quality of the surface protective coating and the climate conditions of the project location.