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Flexbox, adjustable moulds for any type of box culverts

Construx designed a new type of adjustable moulds to produce any type of shaft or core without ties through the concrete element

The system is suitable to make single and double lift shafts, stair cores and box culverts.
The idea of the mould is to start with an adjustable base frame on which all components can be locked into position. The inside mould has 4 hydraulically retractable corners which, when connected without any infill panels, form the minimum shaft size. This size can be chosen at 1200mm x 1200mm, 1000mm x 1000mm or even at 900mm x 900mm. When adding infill panels in between the inside corners, any other internal size can be achieved. Increments can be 250mm or 10mm or anything in between.

The retractable corners can feature a 90° angle (for lift shafts and stair cores) or can have a triangular chamfered corner (for box-culverts), or even a combination of chamfer and 90° angle. In case the mould is going to be used for lift shafts and stair cores as well as for box-culverts, the chamfered corners can have detachable top-up parts. The retractable corners can be operated by means of 4 individual hydraulic hand-pumps or with one single hydraulic group.
After assembling the inside mould, steel bases are fit onto the base frame and against the inside mould. These bases sit on height adjusters and can have different widths, allowing various wall thicknesses for shafts and culverts. The continuous height adjustment systems allows to finish the concrete on top of the mould at all times. The bases can be flat (for lift shafts and stair cores) or have a rebate (for box-culverts).

The outside panels connect to each other in a hit-and-miss configuration. By doing so, any outside size can be achieved, no matter the increments of the inside mould. Outside panels and inside panels are connected to each other with spindles at the base and by means of tie-rods over the top of the mould. So, there is no need for ties through the concrete element, which results in a fair-faced and watertight finish.

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