Flexbox mould for lift shafts, stair cores and culverts
Flexbox
Construx-Weckenmann designed a new type of adjustable moulds to produce any type of shaft or core without ties through the concrete element.
The Flexbox system by Construx-Weckenmann is a revolutionary adjustable formwork solution designed to produce lift shafts, stair cores, and box culverts with fair-faced, watertight concrete surfaces - without ties through the concrete element. Its modular design allows for complete flexibility in size and application, making it ideal for high-precision precast production environments.
No Through-Ties – Smooth, Watertight Results
Unlike traditional shaft moulds, Flexbox eliminates the need for internal tie-rods, resulting in:
- Clean, fair-faced surfaces
- Zero visible tie holes
- Improved watertightness
Connections are made only:
- At the base with spindles
- At the top with external tie-rods
How It Works: Modular & Adjustable Configuration
Adjustable Base Frame
- The system begins with a robust steel base frame
- All mould components lock into position on this base
Inner Mould with Hydraulic Corners
- 4 retractable corners, hydraulically operated
- Without infill panels, they form the minimum shaft size
- Common base sizes: 1200×1200 mm, 1000×1000 mm, or 900×900 mm
- Add infill panels for custom sizes
- Adjust in increments of 250 mm, 10 mm, or any value in between
- Corner profiles:
- 90° angle (for shafts and stair cores)
- Triangular chamfer (for box culverts)
- Hybrid with detachable tops for dual-purpose use
Corners can be controlled via:
- Four hydraulic hand pumps or
- One central hydraulic unit
Wall Thickness & Base Options
After positioning the inside mould:
- Steel base panels are mounted and height-adjusted
- Bases come in various widths to support different wall thicknesses
- Flat base: for lift shafts or stair cores
- Rebate base: for box culverts
A continuous height-adjustment system ensures concrete finishing is always flush with the mould top.
Outside Panel Configuration
- Outside panels connect in a hit-and-miss layout
- Allows for any external mould size, independent of inner mould dimensions
- Connects to the inner mould with spindles at the base and tie-rods at the top
Key Benefits
- No through-ties = fair-faced, watertight concrete finish
- Highly adjustable dimensions in all directions
- One system for lift shafts, stair cores, and box culverts
- Modular corner options (90°, chamfered, hybrid)
- Fast setup and flexible reconfiguration
- Compatible with multiple wall thicknesses and base profiles
Typical Applications
- Single, double, or triple lift shafts
- Stair cores with or without rebates
- Precast box culverts with precise angles
- High-performance solutions for infrastructure, residential, and commercial projects
