Advice About Pumping Concrete.

Managing the Pour.
The key to a successful concrete pump pour is to manage the pour from ordering the pump and concrete, through organising the site, to supervising to pumping operation.

Some guidelines are set out below to assist with planning a pump pour.

When ordering a pump please give the following info:

· Company name.
· Contact name and telephone number.
· Full site address including postcode if known.
· Date and time for the pump, allow approximately 30 minutes for the pump operator to set up the pump.
· Size of pump required.
· Volume and type of concrete including any admixtures, additions, fibres etc.
· Brief description of the pour e.g. footing, external slab, bridge deck etc.
· Any other special requirements pipeline, second man etc.

To ensure a safe and efficient pump pour, please supply the following:

· A level area of hard standing, with no overhead obstructions, on which to set up the pump.

· Clear access to the pump for the truck mixers.
· Cement to grout the pipeline - 1 x 25 kg bags per 10 metres of pipeline.
· Somewhere to deposit excess concrete.
· A good pump mix concrete. Your ready mixed concrete supplier will advise.
· A competent concreting gang to lay the concrete.
· A suitable place for the operator to wash the pump out at the end of the job. At least 1/3 cubic metre of concrete will be left in the pump after the pumping operation.
· A good supply of water will help the operator, though the pump does carry its own supply.

The sequence of a typical pump pour:

· The pump will arrive and the operator will liaise with the contractor before setting up the pump, pipeline (if required) and preparing the grout.
· The concrete mixer truck will arrive and back onto the pump.
· The pump operator will then grout the line and commence pumping. It is good site practise to pump excess grout to waste, not into the pour.
· The concrete will be placed into position using the boom where possible. Where ground-line is used, the concreting gang will need to move the pipeline around as the pour progresses.
· Cautionary note: Concrete is pumped at high pressure. All personnel should be made aware of the risks and dangers associated with end hose usage.
· When the truck mixer has discharged its load, the mixer chutes will be cleaned before the mixer leaves. The chutes should not be washed into the hopper as this could cause a blockage and affect the quality of the concrete.
· The next mixer will then arrive, back on to the pump and discharge its load.
· At the end of the pour, the pump operator will clean all the concrete from the pump and pipeline. This operation will take approximately one hour, more if the job involves a long pipeline.
· The pump operator will then put the boom back into its travel position and load all the ancillary equipment onto the pump.
· The job sheet will then be prepared for the contractor to sign.
· The pump will then leave site and travel back to the depot.

Advantages of Using Concrete Pumps.

· Pumping placement is faster than placement by other methods.
· Pumped concrete can be placed in areas that are difficult or impossible to reach by other placement methods.
· Pumping often results in a savings in manpower and equipment cost and cycle time.
· Pumping can take place under any weather conditions, including snow and rain, since the concrete is protected from the elements during transport to the placement area.
· Pumping can be used when the space available for construction equipment is limited.
· Pumping concrete frees cranes and hoists for other construction operations, such as delivering materials.
· Pumped concrete can be easier to handle because the flow of concrete is directed to the exact spot of placement (whereas cranes and conveyors deposit large piles of concrete that must be moved manually).
· Few obstacles can block a concrete pumping pipeline. Pipelines can corner sharply, pass through narrow spaces, travel over or under walls, etc.
· A continuous supply of pumped concrete can help set a steady work pace for the placement crew, thereby increasing productivity.
· A contractor can vary the placement speed or add lines to fit the pace of the job.
· Flow of concrete remains steady and controlled.
· Pumping concrete allows a contractor to place floor slabs on upper floors before completing the concrete work on lower floors. This provides protection from weather when working on lower floors.
· For large pours, multiple pumps can be set up, allowing several trucks to discharge at the same time.

· Effective pumping distances range up 300 metres horizontally, and 100 metres vertically.

Concrete Mix Design for Concrete Pumps.

· The concrete mix design must be correctly proportioned so that the concrete will flow easily and uniformly through the pipe. The pipeline diameter should be 3-1/2 to 4 times greater than the maximum aggregate size for pumped concrete. This helps ensure that the pipeline will not become clogged.

· Another factor in mix design is the slump of the pumped concrete. A higher slump will cause concrete to flow more readily, making the concrete easier to pump.
However, an excessively high slump can cause the concrete to separate, resulting in plugs in the pump or line.

· What makes concrete Pumpable? Pumpable concrete can be pushed under pressure through a pipeline as a cylinder, separate from the pipeline wall by a lubricating layer of water, cement, and sand (mortar). A concrete mix must be such that the concrete can pass through reducers in the pipeline system, and can go around bends in the line. In order to obtain this type of pumpability, the mix must be dense, cohesive, and have sufficient mortar. (Mortar required depends on the line size, efficiency of concrete pump, and pressure available for pumping concrete).

Concrete Pump Location.

· The most important consideration relating to pump location is pump accessibility.
· Ideally, space for two concrete trucks - one unloading and one ready to unload - should be provided at the pump hopper.
· Usually, pumps should be located as closely as possible to the area to be concreted last.

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