Rotary Bored Piling Specialists

Use Of Tremie To Concrete A Pile Under Fluid


 
Procedures

Step 1 /2


A tremie is a steel pipe built in jointed sections to the required length (in 2.0m, 1.0m and 0.5m sections) with an open end at the base to allow the free passage of concrete, and a hopper (FIG 02) or concrete pump attachment at the top, to enable concrete to be placed from the surface, to the base of the pile, in order to concrete the pile from the base of the pile upwards

The required length of a tremie is from the piling platform working level, to the base of the pile.

  • Diameter :              6 inch (150mm) 8 inch (200mm) and 10 inch (250mm)
  • Rack :          Tremies should be stored in a rack (FIG 03 & 04) (rather than laid down onto the ground) , this is to prevent deformation of the tremie and to avoid the risk of the tremie being lifted without a jointing wire in place.
  • Joints:          Should be watertight, should be greased to allow ease of jointing and separation,
  • and must have O-rings to seal the joint (FIG 05).
  • Wires:         These are used to connect the joints, and must not stick out as they may catch on cages during tremie extraction and get pulled out, thereby disconnecting the joint.


     
Procedures

Step 2 /2


Before starting the concrete pour, Macafil  (FIG 06) will be placed into the hopper of the tremie, (half a bucket for 200mm and 250mm tremie, and a quarter of a bucket for 150mm tremie), and the tremie  be placed gently on the bottom of the bore. The hopper will be positioned low enough to allow the concrete mixer to reverse up to it, and to allow the concrete chute over the hopper.

The concrete will be discharge into the hopper, and as the concrete rises up into the hopper the tremie will be lifted off the bottom of the bore to allow the concrete to flow.

A weighted tape will be used to measure the concrete rise in the pile bore. All relevant data to be entered on Martello Digging and concrete sheet Embedment :  At least 2m of tremie must be left embedded in the concrete at all times, (For Example), when splitting down the tremie, if the tremie is a total length of 22m, no pipes (would /should) be removed until the concrete has risen to 18m, (then a 1 – 2m section may be removed).

Tremie sections should be taken off as and when possible, even if the concrete  continues to flow, this will eliminate the possibility of the cage rising under the upward pressure of the concrete.

The pile should be tremied until concrete is flushed over the top of the casing and sound concrete is evident with no debris inclusions showing. The level to which the concrete is finished will be at a minimum equivalent to the level of the adjacent ground water table. (this is to prevent ground water being at a higher pressure than the fluid  pressure in the concrete, and hence entering the fluid column of concrete)

In the event that the tremie pipe has to be removed from the pile concrete before the pile has been completed, then the tremie pipe shall be reintroduced into the concrete by firstly closing the end of the tremie pipe with a steel end plug.

The tremie pipe will then be lowered into the pile bore to make contact with the reviously placed concrete, and the tremie pipe pushed into the concrete by a minimum of 500mm, and then concrete discharged through the tremie pipe such that the end plug is removed and concrete again starts to flow through the pipe.

Once the concrete has started to flow through the tremie pipe, the pipe will be pushed further into the concrete by a minimum of 500mm, and the pile completed by tremie technique in the normal fashion.

 

 

 

Get In Touch


For more information about our services and how we can help you with your projects, please call us on 01476 570781 or leave us a message below.