Hmmm Jonathan,
Sounds like a typical listening room to me? :^)
Lewm,
The shrinkage of concrete is greatly determined by the water content.....the greater the water content, the more the shrinkage. (George knows what I'm talking about).
I doubt that concrete designed to set under water has much shrinkage.
My experience has been that concrete, as it cures, tends to stick to its edge formwork tenaciously, with most shrinkage occurring within its main body via shrinkage cracks.
That's why great care is usually taken to coat the formwork with 'releasing' agents so that it can be stripped away fairly easily.
If one were worried, or had experiences of the concrete shrinking from it's mould.......one could ensure the internal face of the cylindrical mould was coated with a rough epoxy film to which the concrete would cling.
You actually pre-empted another design I had which was for exposed concrete armpods.
In this case, the metal cylinders would not be permanent formwork, but would be coated with form-release agents so that after initial cure took place, the concrete could be released from its mould by a hammer tap to its top or bottom. This would allow many pods to be cast from the same mould and even pods of different heights to be cast.
The bare exposed surface of the concrete pod cylinder could then be left 'as-is'......or painted as one wished.
Sounds like a typical listening room to me? :^)
Lewm,
The shrinkage of concrete is greatly determined by the water content.....the greater the water content, the more the shrinkage. (George knows what I'm talking about).
I doubt that concrete designed to set under water has much shrinkage.
My experience has been that concrete, as it cures, tends to stick to its edge formwork tenaciously, with most shrinkage occurring within its main body via shrinkage cracks.
That's why great care is usually taken to coat the formwork with 'releasing' agents so that it can be stripped away fairly easily.
If one were worried, or had experiences of the concrete shrinking from it's mould.......one could ensure the internal face of the cylindrical mould was coated with a rough epoxy film to which the concrete would cling.
You actually pre-empted another design I had which was for exposed concrete armpods.
In this case, the metal cylinders would not be permanent formwork, but would be coated with form-release agents so that after initial cure took place, the concrete could be released from its mould by a hammer tap to its top or bottom. This would allow many pods to be cast from the same mould and even pods of different heights to be cast.
The bare exposed surface of the concrete pod cylinder could then be left 'as-is'......or painted as one wished.