Handling Concrete and Precast Elements with Vacuum Lifting

Precast concrete is heavy, has corners that chip easily and usually needs lifting anchors or slings before it can move. Vacuum lifting takes a different route: the lifter seals onto a face of the element and holds it with air pressure. On the right surface that makes precast handling faster and keeps the crew away from the load. On the wrong surface it does not work at all, so this article covers both.

Why precast is awkward to rig

Conventional precast handling depends on what is cast into the element or wrapped around it. Lifting anchors have to be planned, positioned and cast in before the element exists. Slings need a way around or under the load, and they bear on edges and corners where concrete is most likely to chip. Every lift also means people at the element to attach and release the rigging, often while it is still partly suspended.

None of that is wrong, and for many elements it remains the standard method. But for repetitive handling of similar elements, the attach and release steps add up, and edge damage becomes a quality cost on finished products.

How vacuum lifting handles concrete

A vacuum lifter places its pad on a face of the element and pumps out the air underneath. Atmospheric pressure then holds the element against the pad. Nothing has to go under the load or around its edges, and for the lift itself no cast-in anchor is needed. The operator picks the element from above, from a position clear of the load. For the full principle, see how vacuum lifting works.

Because the pad spreads the weight across its whole contact area, the load is not concentrated at sling points or corners. Only the rubber seal touches the concrete, which protects finished and exposed faces.

Surface condition decides

Concrete is the material where surface condition matters most. The pad needs to form an airtight seal, and concrete ranges from glass-smooth to open and rough depending on how it was cast and finished.

The practical rule: lift from the smoothest face the element has, keep that face clean, and if in doubt, test the seal with the element just clear of the ground before moving it.

Typical precast elements

Slabs and floor elements

Flat slabs are the most straightforward case. They have a large, even face and are often handled in repetitive series, which is where vacuum lifting gains the most time. Vlentec's slab lifting attachment is built for this kind of load.

Panels and wall elements

Wall panels cast flat against a mould usually have one smooth face that suits a pad. Panels with a textured architectural finish on one side can often still be lifted from the formed side. Handling elements like these is common in manufacturing and construction, both in the precast plant and on site.

Segments and structural elements

Larger elements such as segments for bridges and tunnels combine high weight with a need for accurate placement. Here the controlled pick and placement from above is the main benefit, as on many infrastructure projects. Each element type should be checked for surface and weight before it is planned as a vacuum lift.

Weight and capacity

Concrete is dense, and precast elements are often heavier than their size suggests. Normal-weight concrete is around 2,400 kg per cubic metre, a little more with heavy reinforcement. A slab 6 metres long, 2.4 metres wide and 0.2 metres thick is 2.88 cubic metres, so roughly 7,000 kg before any margin.

Work out the volume of your heaviest regular element, multiply by the density, and add a margin. Then check that figure at the reach you will work at, because a carrier has less capacity further out. How that leads to the right class is covered in choosing lifter capacity.

Frequently asked questions