Mat Foundation Concrete Placement

[Eldorado]

I have a mat foundation with a 150'x80' footprint and 6' deep - Roughly 2670 CY of concrete. Are there additional placement requirements you would specify for the 6' deep mass of concrete?

 

[asixth]

Typical 12" layers should do.

Some specifications say that concrete is to be placed without causing separation. If you want to be more specific you could say concrete should not fall more than 5'.

 

[hokie66]

I disagree with asixth. Placing a thick mat in layers might work if done quickly enough, but is not practical for 2670 CY of concrete. I would want to place the concrete on the 80' face, proceeding along the long dimension. Plenty of vibration is essential, and care should be taken to avoid settlement cracking around the top reinforcement. Revibration can take care of this potential problem. Depending on the time of year, either good hot weather or cold weather concreting practices may be required.

 

[Eldorado]

hokie66, I agree with your sequence, although I would expect the contractor to have two (2) crews that start at opposite ends and meet in the middle. I'm in Texas and the foundation was suppose to be cast back in February, which was probably ideal here, but April temperatures will be a toss up.

I know this is more of a means and methods issue, so I do appreciate your input. I like to be somewhat educated on which means and methods Don't Work, so I can express concerns if they are proposed.

 

[ATSE]

This is mass concrete.
ACI 207.1.
You definitely need to address means and methods, as this will affect the final product.
Low heat of hydration mix design and temperature controls are a minimum.
A roughened construction joint ("cold joint") in the middle with a 3 day delay between pours will reduce self-restraint.

 

[ferrarialberto]

"Low heat of hydration mix design and temperature controls are a minimum." I agree, absolutly. Is necessary to use a large pieces of gravel.
A thickness of 6 feet of concrete can cast in place in three phases, with intermediate horizontal reinforcement.

ing. FERRARI Alberto -

http://www.ferrarialberto.it

 

[paddingtongreen]

I wasn't directly involved in this, but we used a Creter crane on a big placement, two trucks at a time, one working and one either setting up or moving out, that placement lasted 36 hours but had been calculated for about 31 hours. They had a crew, armed with brushes, on the top bars to make sure that no concrete stuck to them until the level reached them. It was placed in layers but was ten feet deep so not quite the same.

Michael.
Timing has a lot to do with the outcome of a rain dance.