Where flow exceeds the capacity of a single cell, twin or triple-cell box culverts are used. Standard drawings define twin-cell types such as 2×(8×5), 2×(8×6), 2×(9×5) and 2×(9×6).
The formwork problem multiplies: every cell is a separate closed section, and every one has to be stripped. The shared intermediate wall makes it harder still. With MenfeX® each cell's formwork stays in place — there is nothing to withdraw.
The intermediate wall
In multi-cell culverts the wall separating the cells is the critical point for both formwork and reinforcement. How it is formed depends on the cell count and span in your project.
Share your section drawing and we will work out the appropriate configuration together.
Scope
The confirmed standard range is a clear span of 1.00–3.00 m per cell. Larger multi-cell culverts are assessed on a project-specific basis.
Applications
- High-flow stream crossings
- Main drainage canal crossings
- Flood protection works
- Highway crossings requiring wide sections
FAQ
Will plastic formwork withstand the lateral pressure of fresh concrete?
Yes — provided the stated rate of placement and lift height limits are observed.
The lateral pressure fresh concrete exerts on formwork is not constant; it varies with pour rate, lift height, concrete temperature and consistency. This is the same physics for steel and plastic alike — every formwork system is designed to a defined pressure.
The design pressure, maximum rate of placement and maximum lift height for MenfeX panels are stated in the installation guide and on the panel label. Exceeding these limits can deform the panel — a rule that applies to every formwork system.
Will the client's engineer approve stay-in-place formwork?
Stay-in-place formwork is a recognised method, but its use in culverts depends on the project specification and the client's engineer.
Be sceptical of any supplier who tells you it is unconditionally permitted. On public contracts, a change of forming method goes through the supervising engineer and is confirmed in writing.
Raise it during the construction programme, not after award. The technical file to submit and the steps to follow are set out on the Specification & Approval page. We support witnessed trial installations on site where required.
Does the top slab form need propping?
It depends on the clear span. Small spans may need none; larger spans do.
The deck form carries the weight of wet concrete plus construction loads, and that load rises quickly with span. Above a given span, propping is installed beneath the form. Prop spacing by span is tabulated in the technical documentation.
This is not specific to MenfeX — steel systems are propped too. The difference is that here what gets struck afterwards is the props, not the formwork.
How does the cost compare with steel formwork?
Compare total cost per culvert, not the price of the formwork.
MenfeX is a consumable; steel formwork is an investment. Placing the two purchase prices side by side is meaningless. The right benchmark is what it costs to finish one culvert: the per-culvert items that recur with steel — crane, erection, stripping, release agent, cleaning, freight, storage, patching — are absent or much reduced here. Against that, MenfeX is bought for every culvert.
An honest note: if you are casting hundreds of identical culverts in one location with a crane already on site, steel is probably more economical. The calculator will not hide that from you.
Request a Quote
Share your culvert dimensions, quantity and destination. We will return the configuration, container loading and lead time.