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Post by downunderdave on Sept 9, 2016 20:46:47 GMT
8:1 vermicrete is pretty lean for underfloor insulation where some strength is required. The leaner the mixture the more important correct mixing and water addition becomes. Over the dome is different, you want it as lean as is practicable to mix and apply, I find 10:1 is about as lean and workable as I dare. Adequate strength vs insulating capacity is a fine balance. The usual mix for under floor insulation is 5:1. Here are a couple of attachments you may find useful. (there is an error on the physical properties table. The 5:1 should read 175-225 for compressive strength), but note the difference in strength between a 5:1 mix and an 8:1 mix. It's around double and not so different in insulating capacity.
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gulf
New Member
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Post by gulf on Sept 10, 2016 0:56:42 GMT
Just a suggestion. Those are some mighty large saddles holding up the rebar. Especially on a suspended slab, they will weaken the concrete's strength. If it were me, I would take them out. On a pour this small, the first batch of mix can easily be placed in strategic spots to hold the rebar off of the floor. That will ensure that the suspended slab gets the maximum tensil strength that it can.
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Post by lal5000 on Sept 10, 2016 7:45:46 GMT
thanks for both of your comments. having thought about it and having a look, you are both totally correct. the saddles lift the rebar above the centre line into the zone of compression where they won't do much good at all. I will do what you say and dab some concrete on the shuttering and float the rebar on top. that should get it within the tensile zone.
Also I'm very glad you posted the attachments. there is not much difference at all between the ratios in terms of insulating capacity but a good deal of difference in strength. I will lower the ratio to 5-1.
This is the reason I decided to document my build. for points like this to be raised and corrective action to be taken, where possible.
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Post by lal5000 on Sept 10, 2016 10:27:57 GMT
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Post by lal5000 on Sept 10, 2016 11:50:54 GMT
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Post by lal5000 on Sept 10, 2016 17:32:30 GMT
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Post by lal5000 on Sept 11, 2016 16:04:17 GMT
couldn't leave the brick slips the way they were so chipped a few off and tidied them up this morning. think they look a lot better now. the pointing will hide the worst of it. tidied up the front of the log store too so you can't see the concrete blocks. just waiting now for the vermicrete/RC slab to fully cure before moving onto the next stage. don't think it will take more than a weekend to finish off so fingers crossed the weather stays nice. quick question - shall I keep it covered if it rains?
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Post by diggerjones on Sept 11, 2016 18:19:39 GMT
Yes keep it covered. How much are brick slips
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Post by lal5000 on Sept 11, 2016 19:35:46 GMT
ok. will get the tarp over it.
quite expensive but i had some left over from another project. about £30sqm
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Post by lal5000 on Sept 12, 2016 17:04:50 GMT
osmo oiled the oak. pointing hopefully tomorrow evening.
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Post by lal5000 on Sept 14, 2016 6:51:07 GMT
brick slips pointed.
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Post by lal5000 on Sept 14, 2016 19:06:34 GMT
cleaned up the slips with some brick acid. cleaned up a treat. 50mm calsil board on order and blanket. placing order for oven soon as I'm paid!
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Post by lal5000 on Sept 16, 2016 10:19:37 GMT
I've cut my cal sil boards. do I need to seal the edges with aluminium tape? going to be concrete up to edge of them (2 inch gap) but don't want to risk damaging them
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Post by lal5000 on Sept 17, 2016 7:43:11 GMT
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Post by lal5000 on Sept 20, 2016 17:52:28 GMT
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