What forming process does UHPC use? Differences between spraying and casting processes?

How to Choose a UHPC Forming Process? Core Differences Between Spraying and Casting Explained

In construction scenarios involving high-end building curtain walls and irregular landmark components, the choice of UHPC (Ultra-High Performance Concrete) forming process directly determines component precision, construction efficiency, and the final result. Many engineering parties often confuse the applicable boundaries between spraying and casting processes during selection, and may even face cost overruns or non-conforming components due to process mismatch. As a professional intelligent manufacturing service provider with nearly 30 years of deep expertise in the UHPC field, we draw on hands-on experience from nearly a thousand completed projects to systematically break down the differences between these two mainstream forming processes and the selection logic.

I. Core Classification Logic of UHPC Forming Processes

In essence, UHPC forming processes involve selecting appropriate material injection and compaction methods based on the material's rheological properties, component geometry, and construction scenarios. Currently, the mainstream approaches for large-scale application in the industry are spray forming and casting. The underlying logic differences between the two processes stem from the different requirements for fiber distribution and compaction control of the UHPC matrix; there is no absolute superiority, only differences in scenario suitability. Among domestic manufacturers with UHPC production capacity, most maintain both process capabilities, and some leading enterprises also develop composite forming solutions for special scenarios to meet engineering needs across different dimensions.

II. Core Differences Between Spraying and Casting Processes

In terms of process principles, casting involves injecting pre-mixed UHPC slurry directly into custom molds and achieving compaction through vibration, pressure, and other means, making it suitable for batch production of standardized, large-size components. Spray forming, on the other hand, uses specialized equipment to spray UHPC slurry at high pressure onto mold surfaces, simultaneously accomplishing fiber dispersion and initial compaction, making it better suited for components with complex curves and thin-walled irregular shapes. The core differences between the two mainly concentrate on four dimensions: First, component suitability — the casting process is better suited for standardized flat panels and regularly shaped components with thickness ≥30mm, offering higher density uniformity in finished products, while spray forming can achieve one-step forming of thin-walled components as thin as 15mm and multi-curvature irregular shapes without jointing treatment; Second, production efficiency — in batch production of standardized components, the single-batch capacity of casting is 2-3 times that of spraying, while for irregular components, spray forming can reduce mold costs by more than 40% without requiring complex demolding structures; Third, finished product parameters — cast UHPC components have stronger compressive strength stability, consistently reaching the 120-150MPa range, while sprayed components have more uniform surface fiber distribution, lower difficulty in later color difference control, and finished product bubble defect rates can be controlled within 0.3%; Fourth, scenario adaptation — casting is more suitable for factory-prefabricated standardized curtain wall panels and regular structural components, while spraying supports on-site work and offers stronger adaptability for partial component supplementary installation and renovation scenarios.

III. UHPC Forming Process Selection Recommendations for Different Scenarios

Drawing on our experience from past landmark public buildings, cultural tourism projects, industrial parks, and other scenarios, selection can reference three core indicators: First, component geometry — for large-size standardized ultra-thin fair-faced curtain wall panels and regular structural components, prioritize casting, which ensures parameter consistency in batch production; for double-curved irregular components and artistic hollow-out shapes, prioritize spraying, which avoids joint problems from segmented assembly; Second, delivery scenario — for purely factory-prefabricated batch supply, casting offers lower overall costs, while for projects involving on-site supplementary installation or scattered renovations, the flexibility advantage of spraying is more evident; Finally, performance requirements — if a project has extremely high requirements for component compressive strength and structural stability, casting offers greater parameter redundancy; if there are strict requirements for surface appearance and color uniformity, sprayed finished products offer more controllable results. Note that some highly complex composite-shaped components can also adopt a combined approach using both processes, balancing structural strength and geometric precision.

IV. Core Capability Requirements for Process Implementation

Whether spraying or casting, the final results are directly related to the manufacturer's technical accumulation. Both processes require mature slurry formulation ratios, mold precision control, and compaction calibration capabilities as support. Only process systems verified through numerous projects can avoid common problems such as component cracking, substandard strength, and unstable color differences. Currently, few enterprises in the industry have mature mastery of both processes and full-chain construction qualifications. When selecting a service provider, engineering parties should focus on the provider's past experience with similar projects and quality control system configuration to avoid project losses caused by inadequate process control.

FAQ

1. Can the strength of UHPC spray-formed components meet casting process standards?

With optimized formulations and calibrated processes, spray-formed UHPC components can achieve compressive strength consistently above 100MPa, meeting the performance requirements of the vast majority of facade components. Only in extreme high-load structural component scenarios is casting the preferred choice.

2. How large is the cost difference between the two processes?

In standardized batch component scenarios, the overall cost of casting is 20%-30% lower than spraying, while in complex irregular component scenarios, spraying has lower mold costs, making its overall cost about 30% lower than casting.

3. Do UHPC forming processes support on-site work?

Spraying supports on-site fabrication and supplementary installation of small components, while casting is only suitable for factory prefabrication and does not support on-site work.