A concrete placing boom, also called a separate placing boom or a stationary placing boom, is a folding hydraulic arm that carries a concrete delivery pipe and distributes concrete over a floor or into walls and columns. Unlike a truck-mounted boom pump, it has no pump of its own and is not built into a truck. It is installed on the structure, on a pedestal, on a tower or on a mobile base, and it is fed through a pipeline by a separate stationary pump or truck-mounted pump at ground level.
Placing booms are used above all on tall buildings, where they climb with the structure floor by floor, and on large projects where concrete must be placed over wide areas for months or years. On such jobs a placing boom can reduce crane time, speed up each floor cycle and allow concrete to be placed well beyond the reach of any truck-mounted pump.
Brief History of Concrete Placing Booms
Placing booms developed from the booms fitted to truck-mounted concrete pumps. After hydraulic truck-mounted boom pumps appeared in the 1960s, manufacturers saw that the same boom technology could be separated from the truck and mounted on the building itself. This made it possible to combine a powerful stationary pump at ground level with a boom placed high on the structure, where it could distribute concrete across each new floor.
As high-rise construction grew in Asia, the Middle East and elsewhere from the 1980s and 1990s onwards, placing booms became standard equipment on tall buildings. Stationary pumps delivering concrete to several hundred metres, combined with booms climbing inside the core or on the slab, allowed concrete frames to rise quickly. Over time booms became longer and lighter, hydraulic climbing systems simplified relocation, and radio remote control and electric drives became standard. Today the leading concrete pump manufacturers all offer ranges of separate placing booms and the accessories needed to mount and climb them.
How a Concrete Placing Boom Works
A placing boom has the same main elements as the boom of a truck-mounted pump, but it is mounted on a fixed or movable base.
- Boom. Three or four hydraulically operated sections, carrying a steel delivery pipe with swivel joints at each articulation, end in a rubber end hose that directs the concrete.
- Slewing unit. A slewing ring and drive rotate the boom, usually through 360 degrees or more, so that it can cover a circular area around its base.
- Column or mast. The boom sits on a tubular column that raises it above the working level. The column can stand on a cross base with ballast, be fixed to a floor or be installed in a shaft or lift core.
- Hydraulic power unit. An electric motor, or sometimes a diesel engine, drives the hydraulic pump that moves the boom. Electric operation is common because site electricity is available on most high-rise projects.
- Delivery line. A pipeline runs from the stationary pump at ground level up the building to the base of the boom, where it connects to the boom pipe.
- Remote control. The operator controls the boom by radio remote control from the slab, where the pour can be seen directly.
Types of Concrete Placing Booms
Pedestal Placing Booms
The boom stands on a base frame with ballast placed on the slab or on the ground. It can be lifted by a crane and repositioned to cover different areas of a floor.
Climbing Placing Booms
The boom column is mounted in a lift shaft, a stairwell or a floor opening, or on the outside of the core, and is raised floor by floor with the structure. Climbing can be done with a crane or with a hydraulic self-climbing system that jacks the column up without crane time.
Tower-Mounted Placing Booms
The boom is mounted on a lattice tower similar to a tower crane mast, sometimes on the same foundation, and is extended as the building rises.
Mobile Placing Booms
Booms on a crawler, wheeled or rail-mounted base that can travel around a site, used in tunnels, on bridges and on large slabs.
Special Booms
Placing booms for tunnel linings, dam construction and precast plants are designed for particular structures, with special reach, rotation and mounting systems.
Size Classes
| Class | Typical horizontal reach | Typical use |
|---|---|---|
| Small | about 10 to 20 m | Small buildings, precast plants, tunnels |
| Medium | about 20 to 30 m | Residential and office towers |
| Large | about 30 to 40 m and more | High-rise cores, large slabs, major projects |
Figures are indicative. Reach depends on the boom design and on the height of the column above the working level.
Accessories
A placing boom is part of a system, and the accessories often decide how well it works on a given site. Typical items include cross bases and ballast frames for free-standing booms, floor frames and wedges for mounting in slab openings, climbing frames and hydraulic climbing cylinders for core installations, and extension columns to raise the boom above formwork and safety screens. The delivery line needs wear-resistant pipes, bends, couplings and wall brackets on every floor, as well as shut-off valves that stop concrete from flowing back down the vertical line when pumping pauses. Cleaning equipment, such as sponge balls and water or air pressure systems, is used to empty and wash the line at the end of each pour.
Main Manufacturers
- Putzmeister, part of SANY, with a wide range of separate placing booms and climbing systems.
- Schwing, which offers stationary booms alongside its pumps.
- CIFA, owned by Zoomlion, with placing booms for buildings and tunnels.
- SANY, Zoomlion and XCMG, which build placing booms for the large Chinese high-rise market.
Main Uses of Concrete Placing Booms
- Placing concrete on the floors, walls and cores of high-rise buildings.
- Large slabs on industrial and logistics buildings where a truck pump cannot reach.
- Tunnel linings, underground structures and shafts.
- Dams, bridge piers and other large civil engineering structures.
- Precast factories, where the boom distributes concrete over casting beds.
Placing Boom or Truck-Mounted Pump?
The choice depends on building height, project length and site layout.
- Height. Truck-mounted booms reach about 60 m or a little more. Beyond that, a stationary pump with a placing boom is usually the only practical option.
- Duration. For a single pour, a truck-mounted pump is quicker to arrange. For repeated pours over many months, a placing boom avoids daily set-up and reduces cost.
- Site space. Tight city sites may not have room for a large pump truck with extended outriggers, while a placing boom needs only space for the stationary pump and the pipeline.
- Crane time. A climbing boom with a hydraulic climbing system frees the tower crane for other lifts.
- Planning. A placing boom must be designed into the structure, with openings, anchors and load checks agreed with the structural engineer.
Safety
The base of a placing boom must be designed for the forces from the boom, the concrete and the wind, and the supporting slab or core must be checked by an engineer. Ballast, anchors and climbing frames must be installed according to the manufacturer’s instructions. Booms have wind speed limits, and operations must stop in strong winds. Pipelines must be secured at every floor, and couplings and pipe wall thickness inspected, because a burst pipe under pressure can cause serious injury. People must keep clear of the end hose at the start of pumping and when blockages are cleared. Relocating or climbing the boom is a critical operation that should follow a written method statement.
Trends and Technology
Placing boom technology is following the same path as truck-mounted boom pumps. Lighter materials allow longer reach with less weight on the structure. Hydraulic self-climbing systems reduce crane use and speed up floor cycles. Boom control systems damp vibrations and allow smoother movement of the boom tip. Electric drives are standard on many models, making booms quiet and free of local emissions. Sensors and telematics monitor loads, wind and operating data, and placing booms are increasingly integrated with the pump so that one operator can control both from the slab.
Key Terms
- Separate placing boom: a boom used independently of a pump, fed through a pipeline.
- Climbing system: equipment that raises the boom with the building, by crane or hydraulically.
- Pedestal: the base frame and ballast on which a free-standing boom stands.
- Delivery line: the pipeline between the pump and the boom.
- Stationary pump: a pump on a trailer or skid that feeds the pipeline.
- End hose: the flexible hose at the boom tip that directs the concrete.
Frequently Asked Questions
Does a placing boom pump concrete? No. A placing boom only distributes the concrete. It must be connected to a separate stationary or truck-mounted pump.
How is a placing boom moved to the next floor? It is lifted by the tower crane or raised with a hydraulic climbing system, depending on how it is mounted.
Can a placing boom be used outside high-rise buildings? Yes. Mobile and pedestal booms are used on large slabs, in tunnels, on bridges and in precast plants.
What power does a placing boom use? Most placing booms use an electric motor driving a hydraulic unit, although diesel-powered versions exist for sites without mains electricity.
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