In brief
Serious accidents with concrete pumps cluster at four points: the boom approaching an overhead power line, outriggers being set on unsound ground, a blocked line or one being cleared under pressure whipping the hose, and the truck mixer reversing up to the pump. The Regulation on OHS in Construction Work lists these risks one by one; concrete pumps are also subject to a periodic inspection once a year. Concrete pump safety starts with a site survey carried out before the pour.
Concrete pump safety: what does the regulation require?
At 07:00 on a housing construction site in Bursa, the truck mixers have lined up and the pump operator is about to unfold the boom. The boom will rise a few metres from a medium-voltage line passing over the neighbouring plot; one of the outriggers lands on a utility trench that was backfilled two weeks ago. The team says "we always do it like this". Concrete pump safety requires decisions like these to be made on site the day before, not on the morning of the pour.
Annex 4 (B) Part II of the Regulation on Occupational Health and Safety in Construction Work gives a detailed list for concrete pouring (item 81). Those relating to the pump are:
| Item 81 clause | What the regulation requires |
|---|---|
| a | The pump is positioned suitably for the place where concrete will be poured |
| b | The outrigger pads are fixed to the ground appropriately |
| c | Checks to prevent openings at boom and hose joints caused by air pressure |
| ç | Eliminating the risks posed by nearby buildings and power lines when the pump arms are unfolded and folded |
| d | The pump is not operated under power lines; if unavoidable, contact is prevented |
| e, ğ | The hose at the boom tip is handled by safe methods and does not swing about |
| h | Suitable communication if the operator cannot see the pour location |
For other risks during formwork and pouring, see our article on formwork and concrete pouring risks; this article focuses on the pump and the mixer themselves. For the general structure of the regulation, our article on the Regulation on OHS in Construction Work is a guide.
The concrete pump boom and overhead power lines
Concrete pump contact with power lines is the deadliest scenario in concrete work. The boom does not even need to touch the line; at high voltage, coming close enough can be enough to cause an arc. The current passes to earth through the boom, the vehicle body and the hose. The greatest danger at that moment is for the worker below guiding the hose, and for the operator and helpers touching the vehicle.
Item 15 of Annex 4 (B) Part II of the regulation is clear on this:
- If a power line passes near the construction area, work is carried out leaving an adequate safety distance; the swaying of the wires in the wind is taken into account when setting the distance.
- If an adequate distance cannot be left, approval and permission are obtained from the relevant authorities and organisations to reroute the line or cut off its power.
- In areas with power lines, vehicles are kept away from the line with barriers or warning signs.
In practice, follow this sequence: during the pre-pour survey, the location and voltage of the lines are identified; the safety distance is obtained from the pump manufacturer's instructions and the electricity distribution company; and the boom unfolding and pour area are planned around this distance. If the distance cannot be maintained, an application is made to the distribution company to cut the power, and the boom is not unfolded until the outage has been confirmed. During boom movements, a lookout is present whose only job is to watch the line.
Setting up outriggers: pads and ground conditions
When the boom is unfolded, the pump's entire load passes to the outriggers and from there to the ground. The load under an outrigger is far greater than that under an ordinary vehicle wheel. The regulation is also clear for work equipment: work does not start until the soundness of the ground has been confirmed and, where necessary, levelling and stabilisation have been carried out; measures to prevent slipping are taken at trench edges and on steep slopes (Annex 4 (B) Part II item 51).
Before setting up the outriggers, check:
- Ground: outriggers are not placed on newly backfilled trenches, ducts or utilities, on manhole covers, or on fill right next to a basement wall.
- Excavation edge: outriggers are kept at a safe distance from excavation and slope edges; for slope safety, see our article on excavation and trench collapse prevention.
- Load-spreading pads: load-spreading plates or timbers of the size recommended by the manufacturer are placed under the outriggers.
- Full extension: outriggers are extended according to the setup diagram in the manual; the manual states that with partially extended outriggers the boom may only be operated in the permitted zone.
- Level: the vehicle is levelled; outriggers are monitored for settlement throughout the pour.
Pump hose whip and blockages
The flexible pump hose at the end of the boom can whip about as concrete comes out under pressure. The most dangerous moments are:
- Start of pumping: air left in the line comes out suddenly with the concrete and whips the hose.
- Clearing a blockage: pressure builds up in a blocked line; when the plug breaks free, the concrete and hose move suddenly.
- Cleaning with compressed air: the cleaning ball or sponge shooting out of the line at high speed.
- Opening a clamp under pressure: when the joint opens, concrete and fragments are ejected.
Measures:
- Pumping is started slowly; the hose end points towards the formwork, not at the worker guiding it.
- The area the hose end could swing through is treated as a danger zone; nobody is in this area at the start.
- The hose is not bent or knotted; no rigid fitting is attached to its end.
- In a blockage, the pump is stopped and the pressure in the line is released by reverse pumping; clamps are not opened until the pressure has been released.
- When cleaning with compressed air, a catch basket is used at the outlet end of the line and nobody stands in line with the outlet.
- Pipes and clamps are checked regularly for wear and cracks; worn pipe is the most common cause of a burst line.
If there is no visual contact between the worker holding the hose and the operator, a radio or signaller is used (item 81/h).
Manoeuvring behind the mixer and the chute
The first thing that comes to mind with a truck mixer accident is someone being crushed behind the mixer as it reverses up to the pump hopper. The regulation requires a trained signaller to be appointed where the operator's view is restricted, manoeuvring and parking areas for machinery and vehicles to be designated, all manoeuvres to be directed by a supervisor, and audible and visual warnings to work when reversing (Annex 4 (B) Part II items 52–54).
- The mixer's position at the pump and its direction of approach are set in the pour plan and marked on the ground.
- When reversing, nobody stands behind the mixer or between the pump hopper and the mixer; the signaller stands where the driver can see them.
- Handles are used when opening and closing the chute to protect against hands and fingers being trapped.
- No one reaches into the rotating drum or the chute; cleaning and maintenance inside the drum are not done until the drum's rotation energy has been locked out, and are planned as confined space work.
Truck mixer drivers are usually employees of the concrete batching plant. When entering the site, they should learn the site's rules following the principles in our article on contractor induction training and permits.
Daily checks, periodic inspection and documents
Annex III of the Regulation on Health and Safety Requirements for the Use of Work Equipment lists "conveying, spraying and placing machines for concrete and mortar (concrete pumps)" separately: unless the standards specify a period, a periodic inspection is carried out once a year, with TS EN 12001 as the criterion. The same annex requires work equipment to be visually checked and its functions tested by the operator before each start of work, and this to be recorded.
| Check | Who does it? | Record |
|---|---|---|
| Pre-pour site survey (lines, ground, manoeuvring area) | Site manager, OHS specialist, pump operator | Survey note and sketch |
| Daily equipment check (outriggers, hydraulics, boom, pipes and clamps, emergency stop) | Pump operator | Daily check form |
| Annual periodic inspection | Authorised person | Periodic inspection report |
| Short pre-pour meeting | Team leader | Toolbox talk record |
For the short meeting on the morning of the pour, use our article on toolbox talks; for first response to electrical contact, see first aid for electric shock.
In our OHS specialist service, we plan concrete pours with a site survey, and in our periodic inspection service we track the inspection dates of pumps and other equipment. For other risks in the construction sector, see our construction page; for inspection dates, see our OHS calendar tool.
Frequently Asked Questions
How often should a concrete pump undergo periodic inspection?
Under Annex III of the Work Equipment Regulation, once a year unless the standards specify a shorter period; the criterion is the TS EN 12001 standard. In addition, the operator carries out a visual check and function test before each use.
Can a concrete pump be operated under a power line?
Under the regulation, a pump is not operated under power lines; where unavoidable, the necessary measures are taken to prevent contact with the line. If an adequate safety distance cannot be maintained, permission is obtained from the relevant authority to cut the power to the line.
Who should hold the hose end?
A worker trained for this job who can communicate with the operator should hold it. At the start of pumping and after a blockage, nobody should be in the area the hose could swing through.
Does the truck mixer driver have to follow the site's OHS rules?
Yes. Even though the driver is another employer's worker, they follow the site's rules while working there. The site employer gives information to their employer so that workers coming to its workplace receive the necessary information.
A certified specialist matched to your hazard class: site inspections, approved logbook, training plan, annual plan and report follow-up.
Bursa SİSTEMER OSGB Technical Team — written from the field experience of our OHS specialists and workplace physicians. Legal information is valid as of the publication/update date; contact us for an assessment specific to your business.