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Excess concrete


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I think I'm right in saying concrete companies charge you extra to remove an unused concrete that is ordered (so you pay twice). I'm sure I remember someone on Ebuild mentioning a use for any extra concrete they had. Anyone remember it or any suggestions?

 

Cheers

 

Vijay

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Ah, one BM did mention mixing on site but I didn't think too much about it. I guess it would make sense so I'll look into that too.

 

Just look at the BM quote who mentioned mixing on site - £20+VAT per m3 more than my cheapest quote :(

Edited by Vijay
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Sorry but C30 is not suitable for reinforcing - you have to use an "RC" spec concrete.

 

By putting the rebar into you are then reinforcing it which changes the spec. 

 

Have you queried this with the SE..?? Getting 65 CuM wrong is a very expensive mistake ...!

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I would contact the concrete company and speak to one of their technical people. Before we ordered our concrete for the ICF I had quite a few conversations with the concrete company who referred to their labs a couple of times to get the best mix for the pour. 

 

I never realised just what a black art concrete was until our pour - but the guys we used at Breedon took into account how we were pouring, what we were pouring into, how we needed it to pour, go off etc and came up with a bespoke mix. 

 

I've just looked at the spec for our garage with RC foundations and there is no specific concrete mix. The remember engineer referred us to the ICF company for their spec for the house walls. 

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1 hour ago, PeterW said:

Sorry but C30 is not suitable for reinforcing - you have to use an "RC" spec concrete.

 

By putting the rebar into you are then reinforcing it which changes the spec. 

 

Have you queried this with the SE..?? Getting 65 CuM wrong is a very expensive mistake ...!

I emailed the SE last night asking

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3 hours ago, PeterW said:

Sorry but C30 is not suitable for reinforcing - you have to use an "RC" spec concrete.

 

Sorry but that's not really true.

 

RC30 and C30 should technically be the same strength and both (depending on the situation) should be perfectly suitable for use with reinforcement.

 

RC30 is whats known as a 'designated mix' with certain properties such as cement type, content and water / cement ratio already specified (in BS 8500). Its basically like an off the shelf product, although some things can vary. Other examples of designated mixes are usually have either GEN FN or RC before them with the 30 in this case being its compressive strength.

 

C30 concrete is a concrete with a compressive strength of 30 N/mm2. if this was specified on a drawing for instance, certain properties should be specified else where on a separate specification. Although they normally aren't  and it doesn't really matter either way because the concrete supplier will assume something reasonable and you'll probably end up with the same product anyway.   

 

 

 

 

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6 hours ago, Daedalus said:

Sorry but that's not really true.

 

RC30 and C30 should technically be the same strength and both (depending on the situation) should be perfectly suitable for use with reinforcement.

 

Technically yes, in reality a BCO could ask for the ticket and if you have a non RC spec with reinforcing then you may have an issue. 

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On 09/02/2017 at 20:10, ProDave said:

Think of where you might need some in the future? e.g foundations for a ramp to the front door? always handy to have a prepared space to pour any spare.
 

Is it ok to mix different concretes though, will they bond ok?

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8 minutes ago, PeterW said:

 

 

Technically yes, in reality a BCO could ask for the ticket and if you have a non RC spec with reinforcing then you may have an issue. 

I'm still waiting on the SE but I will check and double check before I order any concrete

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18 hours ago, PeterW said:
On 10/02/2017 at 13:34, Daedalus said:

Sorry but that's not really true.

 

RC30 and C30 should technically be the same strength and both (depending on the situation) should be perfectly suitable for use with reinforcement.

 

Technically yes, in reality a BCO could ask for the ticket and if you have a non RC spec with reinforcing then you may have an issue. 

 

Not that I want to have a disagreement with anyone but there's not really a technically about it..

 

The suitability of concrete from a specifiers perspective is that strength is the only really important parameter. The RC in front of the 30 is only a suggestion and does not mean that all other concrete's are inferior etc etc. There's really no such thing as an RC spec concrete is what I am rabbiting on about.

 

18 hours ago, Vijay said:

Is it ok to mix different concretes though, will they bond ok?

 

Use a scabbler if required to prepare a surface prior to casting

 

18 hours ago, Vijay said:
18 hours ago, PeterW said:

 

 

Technically yes, in reality a BCO could ask for the ticket and if you have a non RC spec with reinforcing then you may have an issue. 

I'm still waiting on the SE but I will check and double check before I order any concrete

 

+1 trust nothing you read on the internet

 

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Just to change the subject a little you say your having 65m delivered. 

Are you going to put all this in with your dumper or can you get the trucks up to the trench so you can shoot a couple of loads in straight of the truck. 

Unless im mistaken 65 m is a big amount to shuffle about in a small dumper. 

What are people's thoughts. 

 

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54 minutes ago, Daedalus said:

Not that I want to have a disagreement with anyone but there's not really a technically about it..

 

I think this is the rub here - this is the differences in BS8500 and others between prescribed mixes and designated mixes. Both have the same strength class but both can potentially be different mixes depending on how they are used and where. But like @ProDave I've never seen a reinforcement in a foundation that hasn't had an RC spec for the concrete. 

 

Whilst I don't disagree with what you're saying about mixes, it's a lot easier to check now and confirm in writing from the SE than  wait until you've got a hole full of the wrong stuff ... 

 

@Vijay was your house designed as ICF from the outset or are the starter bars an addition to the original design.  That may potentially change the SE view. 

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