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Post by ianvisits on Feb 8, 2012 15:41:08 GMT
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Deleted
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Post by Deleted on Feb 8, 2012 16:17:58 GMT
Thank you for this post, it is extremely interesting. Two points come immediately to my mind:
1. Did they say how long it takes for the concrete in each segment to set?
2. Do the segments really come out leaving a pristine mould behind?
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Post by ianvisits on Feb 8, 2012 17:07:14 GMT
1. Must admit, I forgot to ask - however, based on the throughput they are expecting to achieve, I would be surprised if it's more than a day as they don't have enough moulds to sit there curing for longer than that.
2. Yes - There is a plastic sheet over the top during curing, which probably helps, but genuinely we saw a couple being removed by staff working as normal, and the inside probably just needs a wipe down at most.
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Ben
fotopic... whats that?
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Post by Ben on Feb 8, 2012 20:04:05 GMT
Quick setting cement can take very little time to set. Depending on the composition some take as little as ten minutes!
Concrete moulds can be lightly greased to aid in removal. Can only speak from making cubes, cylinders and re-bar beams, but the process upon the mould after 'extraction' was to scrape any remnants off using a scraper, wipe down, and grease. Quicker than it sounds, using high pressure air though might be more suitable at industrial scales. But yes, on a smooth surface theres very little left!
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Deleted
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Post by Deleted on Feb 8, 2012 22:30:53 GMT
The BBC reported at www.bbc.co.uk/news/uk-16289051 (jump to 1:57) that "they take almost a month to set completely solid." Obviously they wont sit in the moulds for that lenth of time, as Ian has pointed out; later in the segment they report production of 216 daily at that plant, so I expect they sit in the moulds for 1 day only. |
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rincew1nd
Administrator
Junior Under-wizzard of quiz
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Post by rincew1nd on Feb 9, 2012 20:37:35 GMT
This sounds a bit like when making suppositories. You either need a modern (expensive) material that doesn't adhere to the mould, or a releasing agent to lube the mould with first. The first time I got to play with morphine we had to make Morphine 10mg suppositories (the logic being that as Undergrads' we would be less tempted to steal our finished products). There is also the consideration of shrinkage, when I make headboards I have to use an expansion rule to compensate, with suppositories, particularly those of Theobroma Oil, if un-lubricated you can end up with the product adhering to the walls of the mould. One never forgets being struck over the back of the head with a Theobroma Oil "suppository" prepared in a 250ml conical measure. |
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Deleted
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Post by Deleted on Feb 9, 2012 22:15:25 GMT
This sounds a bit like when making suppositories. You either need a modern (expensive) material that doesn't adhere to the mould, or a releasing agent to lube the mould with first. The first time I got to play with morphine we had to make Morphine 10mg suppositories (the logic being that as Undergrads' we would be less tempted to steal our finished products). There is also the consideration of shrinkage, when I make headboards I have to use an expansion rule to compensate, with suppositories, particularly those of Theobroma Oil, if un-lubricated you can end up with the product adhering to the walls of the mould. One never forgets being struck over the back of the head with a Theobroma Oil "suppository" prepared in a 250ml conical measure. This post has quite probably ruined my first trip on Crossrail (whenever that turns out to be). As the train descends into the tunnel portal at Pudding Mill Lane the enduring image of a suppository being inserted into some poor soul's Samantha Janus will be too much to deal with. |
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Post by trt on Feb 10, 2012 10:13:23 GMT
Don't worry, you'll just be passing through.
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Post by ducatisti on Feb 10, 2012 16:00:41 GMT
to steer the subject back on topic... (I know, sorry...)
Does anyone know the reasoning between using lorries to ship the concrete from mixer to mould? Given how many sites etc have concrete pumps now, I wonder why such a system was not chosen here?
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