Vijay Posted May 15, 2017 Share Posted May 15, 2017 Planning on the foundation concrete going in on Thursday and just wondered the best way to vibrate the concrete. I'll be using a poker, but do I start vibrating as soon as the concrete starts going in or do I wait for it to fill up a bit? The foundations are 600 and 900mm. Cheers Link to comment Share on other sites More sharing options...
PeterW Posted May 15, 2017 Share Posted May 15, 2017 Shouldn't need vibrating unless you've got lots of rebar in the trenches ..?? Pump grade is very liquid and will flow without it. Link to comment Share on other sites More sharing options...
Vijay Posted May 15, 2017 Author Share Posted May 15, 2017 There's 400mm rebar going in at the top (200mm in 200mm out of the concrete) Link to comment Share on other sites More sharing options...
PeterW Posted May 15, 2017 Share Posted May 15, 2017 So that's added after it's started to go off ..? If there was a lot of box section rebar and you were pouring direct then I can understand it but for pump grade concrete with 10mm aggregate and probably 150/160 slump then I can't see why you need to. Link to comment Share on other sites More sharing options...
Mr Punter Posted May 15, 2017 Share Posted May 15, 2017 Tamping will be fine. You need to try to get the concrete to completely cover the rebar, to prevent rusting / spalling, but this is v. unlikely to be an issue with foundations below ground. Link to comment Share on other sites More sharing options...
Vijay Posted May 15, 2017 Author Share Posted May 15, 2017 3 minutes ago, PeterW said: So that's added after it's started to go off ..? If there was a lot of box section rebar and you were pouring direct then I can understand it but for pump grade concrete with 10mm aggregate and probably 150/160 slump then I can't see why you need to. Yep, the rebar goes in after the pour and once the concrete has set enough to support them. I'll check with the concrete guy but I'd be happy if you're right Link to comment Share on other sites More sharing options...
Vijay Posted May 15, 2017 Author Share Posted May 15, 2017 4 minutes ago, Mr Punter said: Tamping will be fine. You need to try to get the concrete to completely cover the rebar, to prevent rusting / spalling, but this is v. unlikely to be an issue with foundations below ground. No, the rebar needs to protrude the foundations as it sits in the ICF Link to comment Share on other sites More sharing options...
PeterW Posted May 15, 2017 Share Posted May 15, 2017 7 minutes ago, Vijay said: Yep, the rebar goes in after the pour and once the concrete has set enough to support them. I'll check with the concrete guy but I'd be happy if you're right You can over vibrate concrete and cause weaknesses if you're not careful - I would be really surprised if it's needed Link to comment Share on other sites More sharing options...
Vijay Posted May 15, 2017 Author Share Posted May 15, 2017 I'll update this thread once I've spoken to them Link to comment Share on other sites More sharing options...
jamiehamy Posted May 15, 2017 Share Posted May 15, 2017 I would echo previous comments - if you get a nice flowing mix no poking should be required. Tamping should be enough. Get your laser level charged before you forget! Have you got your datum point/s set for measuring? Link to comment Share on other sites More sharing options...
Vijay Posted May 15, 2017 Author Share Posted May 15, 2017 It's already charged up and ready Profile boards are done and centres are marked to line up the rebars. A few more jobs tomorrow and I think I'm ready - only issue is the weather Link to comment Share on other sites More sharing options...
jamiehamy Posted May 15, 2017 Share Posted May 15, 2017 Fingers crossed for you. When we were doing ours, the pump/concrete company said you are able to call it off if you call early enough (i.e before the first batch is made) if you know the weather is to be really bad. I hired a wet n dry vacuum cleaner for ours to sook up any moisture that had gathered on the DPM - probably a bit OTT but it took the condensation off it. Have you planned your control joints? I'll tell you this now to save you feeling down - the concrete will crack somewhere! Link to comment Share on other sites More sharing options...
jamiehamy Posted May 15, 2017 Share Posted May 15, 2017 Our pour! Link to comment Share on other sites More sharing options...
Vijay Posted May 15, 2017 Author Share Posted May 15, 2017 It's only the foundations, floor is B&B Link to comment Share on other sites More sharing options...
jamiehamy Posted May 16, 2017 Share Posted May 16, 2017 8 hours ago, Vijay said: It's only the foundations, floor is B&B Doh! Getting ahead of myself! Link to comment Share on other sites More sharing options...
Vijay Posted May 16, 2017 Author Share Posted May 16, 2017 lol and trying to give me extra work Link to comment Share on other sites More sharing options...
Vijay Posted May 16, 2017 Author Share Posted May 16, 2017 Spoke to the concrete people (he actually visited the site), they said you don't have to vibrate the concrete but it would help eliminate any potential bubbles Link to comment Share on other sites More sharing options...
Triassic Posted May 17, 2017 Share Posted May 17, 2017 (edited) Just out of interest, would you poker concrete going into formwork? If so, when? Edited May 17, 2017 by Triassic Link to comment Share on other sites More sharing options...
Bitpipe Posted May 17, 2017 Share Posted May 17, 2017 1 hour ago, Triassic said: Just out of interest, would you poker concrete going into formwork? If so, when? Our guys poured 2.8m high walls (300mm thick, 6m lengths) for the basement and used the poker all the way down as soon as the concrete was in the formwork, they also ran the poker over the surface of the formwork on both sides. When it was struck it was perfectly smooth with no honeycombing at all. Pretty essential for waterproof concrete I understand to ensure the aggregate is properly mixed and there are no air pockets. We also had window apertures cast (essentially 'holes' in the formwork) and they worked to get the poker underneath these to make sure the concrete was filling them properly, again no issues. For me, this is one of the drawbacks of ICF, you can't see the quality of the resulting pour. Link to comment Share on other sites More sharing options...
Vijay Posted May 17, 2017 Author Share Posted May 17, 2017 1 hour ago, Triassic said: Just out of interest, would you poker concrete going into formwork? If so, when? Polarwall said you don't need to. From what I understand, if you get the concrete mix right, there's no need to vibrate it. I see where Bitpipe is coming from, almost seems like hope to believe it's gone into all the nooks and crannies in the formwork Link to comment Share on other sites More sharing options...
Vijay Posted May 17, 2017 Author Share Posted May 17, 2017 14 hours ago, Vijay said: Spoke to the concrete people (he actually visited the site), they said you don't have to vibrate the concrete but it would help eliminate any potential bubbles So what's your thoughts on this guys, would you still not bother? Concrete is on for tomorrow Link to comment Share on other sites More sharing options...
jamiehamy Posted May 17, 2017 Share Posted May 17, 2017 Have it standing by @Vijay. You'll be able to see how well it is flowing and make a call then. Watch carefully and see how is is physically flowing into the corners etc. Whatever you do, light touch rather than vibrate to heck and separate the mix - don't be too trigger happy. I'll be thinking of you tomorrow! Link to comment Share on other sites More sharing options...
Onoff Posted May 17, 2017 Share Posted May 17, 2017 Sort of on thread but I've done a couple of small concrete areas (bathroom floor, shed base, astronomy pier base) and used Everbuild's waterproofer from T'station in the mix. It says on the label it's also a de-aerator and does what it says. You get hardly any "bubbles" when you tamp it down. Link to comment Share on other sites More sharing options...
PeterW Posted May 17, 2017 Share Posted May 17, 2017 There is a BIG difference between formwork and ICF...!! Formwork is either temporary wooden or steel shuttering designed to retain the concrete mass - ICF is just an outer insulation shell and normally needs additional bracing to retain the pour. I've never seen a manufacturer of ICF recommend a poker used on their product and most actively discourage as a poker touching the side of ICF will most likely blow a hole in it. If you have pump grade concrete it usually includes various chemicals to make it flow - air in pump grade is highly unlikely as its much more fluid than normal concrete. The issue is that because of this if you vibrate it too much then it will separate the aggregate and it will become weaker. Link to comment Share on other sites More sharing options...
Vijay Posted May 17, 2017 Author Share Posted May 17, 2017 6 hours ago, jamiehamy said: Have it standing by @Vijay. You'll be able to see how well it is flowing and make a call then. Watch carefully and see how is is physically flowing into the corners etc. Whatever you do, light touch rather than vibrate to heck and separate the mix - don't be too trigger happy. I'll be thinking of you tomorrow! That was exactly my plan, rather have it and not need it. Cheers mate, gonna be a huge step tomorrow and as nervous as I am right now, majorly excited too - even though I'll have to be up at 4.30 tomorrow morning..... 1 Link to comment Share on other sites More sharing options...
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