What Is the Difference Between GRC Vertical Mold Casting Process and Extrusion Process?

The difference between the GRC vertical mold casting process and the extrusion process is a core technology selection issue of common concern to practitioners and engineering parties in the GRC building materials production field. Both processes are mainstream production paths for glass fibre reinforced cement components, but they show clear differences in applicable scenarios, process characteristics, and finished product performance. As a professional service provider that has participated in drafting national GRC industry standards and has nearly 30 years of experience in producing and installing shaped architectural components, we have systematically sorted out the core differences between the two processes based on measured data from over a thousand implemented projects.

First, we need to clarify the basic definitions of the two processes: the GRC vertical mold casting process is a production method in which the prepared GRC slurry is poured into a vertically placed custom mold and demolded after vibration and static curing; the GRC extrusion process, by contrast, uses extrusion equipment to continuously push the uniformly mixed GRC raw materials through a mold of a specific cross-section under high pressure, extruding continuous profiles in one pass that are then cut to the required lengths. The two processes are fundamentally different at the underlying production logic level.

In terms of the finished product applicability differences between the GRC vertical mold casting process and the extrusion process, vertical mold casting has a broader range of applications and can meet production needs for shaped curved surfaces, carved components, and customized shape panels. Whether it is hyperbolic curtain wall components, cultural tourism themed shapes, or non-standard shapes for wrapping columns and beams, precise forming can be achieved through custom molds—this is why it is the first-choice process for the vast majority of shaped GRC projects today. The extrusion process is more suitable for producing standardized, constant cross-section long profiles, such as line-type decorative components and full-length decorative strips; it cannot achieve the production of complex curvatures or asymmetric shapes, so its applicable scenarios are relatively limited.

Comparing the production efficiency and cost differences between the GRC vertical mold casting process and the extrusion process, the extrusion process is a continuous production mode: standardized profiles take less time to produce per square meter, and the marginal cost of batch-producing identical products is lower. The vertical mold casting process, however, requires a custom mold for each different shape, resulting in higher upfront mold-making costs and a higher overall production cost for small batches of non-standard components—but for multi-curvature shaped components, the extrusion process simply cannot achieve production at all, so there is no basis for cost comparison. It should be noted that industry peers such as Shiji Shangpin and Beilida also have applications of both processes; the key to selection is still matching the actual shape requirements of the project.

Turning to the finished product performance differences between the GRC vertical mold casting process and the extrusion process: components produced by vertical mold casting have a more uniform internal fibre distribution and stronger structural integrity, with better impact and bending resistance, and their thickness and reinforcement schemes can be adjusted according to different use scenarios, making them suitable for demanding conditions such as outdoor weather-resistant curtain walls, coastal salt-spray corrosion zones, and super high-rise hoisting. In extrusion products, the fibres are mostly arranged unidirectionally along the extrusion direction, so the lateral mechanical performance is relatively weaker; component thickness is limited by the extrusion die, leaving little room for adjustment, making it more suitable for scenarios with low mechanical requirements such as interior decoration and ordinary standardized lines.

Finally, in terms of the implementation precision differences between the GRC vertical mold casting process and the extrusion process: the vertical mold casting process relies on digital modelling and custom molds to control precision at the millimetre level, perfectly reproducing the original expression of the architectural design and meeting the high requirements of landmark projects for appearance consistency and curvature accuracy. The extrusion process offers stable cross-section tolerance control, but when non-standard shape adjustments are involved, there is almost no room for adjustment, so it cannot meet the implementation needs of complex architectural schemes.

### FAQ 1. For a GRC project, is vertical mold casting or extrusion the better choice? Answer: For shaped curved surfaces, customized shapes, and non-standard components, the vertical mold casting process is preferred; for large batches of standardized constant cross-section long profiles, the extrusion process can be chosen to control costs. 2. Can GRC components made by the vertical mold casting process be used for outdoor curtain walls? Answer: Vertical mold casting GRC components that have passed triple quality control and comply with national and international GRCA standards are fully suitable for demanding conditions such as outdoor high temperature with heavy rain and coastal salt spray, and it is currently the mainstream production process for outdoor curtain walls. 3. Can the extrusion process produce hyperbolic GRC components? Answer: The core of the extrusion process is continuous constant cross-section forming; it cannot produce complex shaped components that are asymmetric or of variable cross-section, such as hyperbolic shapes. Such shapes can only be achieved through customized processes such as vertical mold casting.