An overview of concrete pumping
Concrete pumping is a technique used in construction sites to deliver liquid concrete and mortar via a series of co-joined pipes. A pumping mechanism is employed in pushing the concrete through specially designed pipes.
When concrete pumping came into existence in the late 1920s, it had a significant impact on the construction of storey buildings. Prior to this, the task of erecting high-rise buildings required a crane to lift large buckets of concrete up and down the structure.
The concrete pumping process uses concrete pumps. Typically a concrete pump comprises a hydraulic pumping system, a hopper where the concrete is contained, and interconnected hoses via which concrete is pumped and placed wherever it's needed.
Advantages of Using Concrete Pumping over Cranes
Concrete pumping has a number of advantages when compared to using cranes to deliver concrete.
- Concrete pumps are faster. They place larger volumes of concrete per hour. While a crane is limited to only 12m³ an hour, a concrete pump can push over 90m³ per hour up a high-rise building.
- Concrete pumps can place liquid concrete precisely using the robotic arm. The mobile pumps can also transport the concrete to specific areas within the site.
- Unlike cranes which can only deliver one bucket at a time, concrete pumps can place concrete as soon as the mixer discharges it thus ensuring a constant flow.
- The continuous flow of concrete ensures that lesser time is wasted since workers do not have to wait for the crane to load and unload. The crane is also freed up for other duties.
- Lower labour costs since these pumps do not need many people to operate. It is also possible for a mobile pump to do many jobs in a day thus the owner reaps from the accrued economies of scale.
How Concrete Pumps Operate
All the concrete pumps mentioned above use pistons, cylinders and valves within their hydraulic pumping system to push and convey liquid concrete through pipes. The valves normally used are: tube valves, seat valves and stone valves.
Concrete pumps also have a folding mechanism that facilitates easy transport after use.
Except for specialised concrete pumps, all other types can be mounted on trucks or trailers that can either be mobile or stationary.
Types of concrete pumps
There are four main types of concrete pumps in the market today.
Line pumps, also known as Stationary Line Pumps or Trailer Mounted Pumps, are static concrete pumps mounted on a trailer and require hoses, made of steel or other material, to be manually attached to the discharge port.
Since these pumps are stationary, they have to be towed to the construction site.
Line pumps usually push lower volumes of concrete compared to boom pumps; the second type of concrete pumps.
The advantage of using line pumps is that the pipes can be very long; allowing the pump to be placed hundreds of metres away from the construction site. This is a very important attribute especially when building tunnels.
These pumps are carried on the back of trucks or semi-trailers.
Though boom pumps are quite similar to line pumps in their operation, they have a remotely-controlled robotic arm known as a boom affixed.
The arm enables precise placement of concrete during construction. Because the hydraulic robotic arm can be manoeuvred and rotated in different directions, it allows boom pumps to be used in construction sites with many obstacles that prevent normal placement of concrete.
Boom pumps are also recommended for projects where there is limited space to lay down inter-connected pipes such as those used in line pumps.
Contractors of large construction projects prefer this type of concrete pump because the robotic arm will accurately place concrete without the need for additional personnel, thus saving on labour costs. The ability to pump very high volumes of concrete quickly additionally makes this pump ideal for such projects.
Truck Mixer Concrete Pumps
As the name suggests, these pumps are mounted on trucks.
They combine a truck mixer, a concrete pump and a placing boom all in one unit.
Taking into account cost efficiency; for instance, the fact that no extra transport is needed, truck mixer pumps are ideal for the smaller construction projects such as building swimming pools and walkways.
The pumps are specially designed for specific construction works such as construction mines. They can be mounted on a skid or on a light rail as informed by the nature of the assignment.
These concrete pumps are expensive due to the high cost incurred when fabricating such custom equipment. As a result, they are uncommon.
Other Ways of Classifying Concrete Pumps
Concrete pumps can also be categorised according to their reach and performance.
Mobile boom pumps can range from 20m to 63m in length. They are further classified as R-fold, Roll-fold, Z-fold, RZ-fold, LRZ-fold, and RZ fold X-style depending on the length, folding mechanism, and the type of placing boom used.
Likewise, stationary boom pumps have 2 more classifications dependent on the volume of concrete they can pump within a specified time.These are:
- 90 cubic metres per hour trailer pump for commercial work
- 100 cubic metres per hour trailer pump for high-rise construction
The same criterion is also used for grouping truck-mounted line pumps as shown below.
- 90 cubic metres per hour truck-mounted pump
- 100 cubic metres per hour truck-mounted pump
- 130 cubic metres per hour truck-mounted pump
What to Do Before Hiring a Concrete Pump
Before hiring a concrete pump a number of things, as listed below, need to be done
- For huge projects, remove any obstructions to enable the concrete mixer to turn and move back and forth
- Level the area
- When ordering concrete, ask the supplier for extra cubic metres. You also need to inform the supplier that you will be using a concrete pump
- Set up a disposal area for extra concrete
- Find and hire competent people to lay the concrete including a concrete contractor to supervise the work.