Tremie placement with SCC

[dgn1012]

Does anyone have experience with using a SCC for placement of concrete inside a pile using a tremie pipe. This is a true tremie situation into water. Contactor plans on using a pump and not a gravity hopper.

My concern is that the SCC will not have the ability to keep the tremie embedded in fresh concrete and will just move out of the way with each stroke of the pump.

Any experience or thoughts?

 

[civilperson]

SCC, what is it? If you are referring to a concrete positive displacement pump, such as Schwing, then that is the best way to go. The operator will leave the outlet end of the pipe/hose in place until 2-3' of concrete is above its elevation. Then will raise the pump up maintaining the 3' concrete cushion above the outlet. When the form is filled, discard the top 4-6" as water contaminated and finish.

 

[Zambo]

SCC - self compacting concrete.

Most bored piles are constructed using high workability concrete, if measured by slump around 200-250mm. This is not the true definition of self compacting concrete, but does not require vibrators for compaction.

Tremie pipes are good as they come in standard lengths of say 4 or 6m so it is very easy to check the location of the end of the tremie pipe compared to the level of the concrete in the bore. With a pump and operator it will be more difficult (perhaps guage lines should be marked on the pump hose before starting) Pump booms tend to jump about a bit during operation.

I would prefer casting into bentonite or polymer. But if water is suitable I think civilperson means to discard 4-6' not 4-6".

 

[civilperson]

Less than one foot of the top of the fresh concrete needs to be suspected in a underwater pour. I have made cylinders of the six inches of concrete at the top of a submerged concrete placement with no significant loss of compressive strength, (after discarding 4 inches of assumed diluted mix in a 48" diameter pier).

 

[GeoPerson]

Tremie concrete is the way to go especially for underwater situations. I agree with civilperson that a minimum of 2’-3’ of concrete head pressure should be maintained until the pile is filled. It is the contractor methods and means to deliver the concrete. For most cases, they will use pump to fill the pile depending on the length of the pile (gravity pressure won’t be enough). During inspection, make sure that the pump is at a constant pressure. Concrete is poured until the fresh concrete is spilled out of the pile (or fresh contaminated water “gray water” is spilled out).

Good lock