Vijay Posted June 9, 2017 Share Posted June 9, 2017 Morning guys, Having a little issue with finding a concrete supplier who will give me the exact spec I require, which is: DESIGNATED CONCRETE to external walls Designation: RC32/40. Fibres: Not required. Aggregates: - Size (maximum): 10 mm. - Coarse recycled aggregates: RCA permitted. - Additional aggregate requirements: Rounded coarse aggregate. Special requirements for cement/ combinations: CEM 1 Consistency: S2 slump range with an ideal slump to around 80mm Chloride class: Normal. Admixtures: Waterproofing admixture below d.p.c. to wall system manufacturer's approval or a high cement concrete to BS8007 with minimum cement content of 325kg/cu.m and water cement ratio of 0.5. Just looking for some help with what things mean. Firstly, the RC32/40 - is that the strength of the concrete? From other posts, I believe the R stands for reinforced as it will have rebar in it? I've been assured that having a minimum cement content of 325kg pcm and water cement ratio of 0.5 will give me a waterproof concrete without the stupid expense of waterprrof additive, but has anyone come across this before as I'm a little worried about that? Vijay Link to comment Share on other sites More sharing options...
Temp Posted June 9, 2017 Share Posted June 9, 2017 (edited) Ask the person who specified that why it's so difficult to find and can it be relaxed. Yes 32/40 relates to the strength. http://www.grabtrucks.com/ready-mix-concrete/mix-design/ Quote RC32/40 "Designated Mix" achieving 40 Newton/28 day strength. Consists of a minimum cement content, 4-20mm stone, graded sand and water. Can be supplied with 10mm stone for specialist applications, subject to a cost premium. A water cement ratio mix to a 0.55 value. Ask if it's essential the stone be <10mm. I'm not sure I would rely on concrete being waterproof but perhaps you are adding braces to your belt. Edited June 9, 2017 by Temp Link to comment Share on other sites More sharing options...
ToughButterCup Posted June 9, 2017 Share Posted June 9, 2017 @Vijay, I have learned one thing about concrete: what is specified is often not what gets delivered. I say this on the basis of about five deliveries (or so), and having bought several lots of cheap concrete from a lets say 'informal' supplier. Our main builder explained that, unless you know the production and delivery companies - the real people on the end of a phone - then you are likely to get generally strong concrete, or middling concrete or weak concrete. Here are a few factors affecting what actually gets delivered How do you know you arent getting the tail end of someone else's delivery - to a different spec - topped up with your spec? How well do you know the company dispatcher (for the lorries)? Not at all? He'll smell it and might well take advantage of that Is the concrete going to be pumped? If so more cement is added to make it 'slippier' in the pipes Is the concrete going to be tested? If not, lie and tell everyone that samples will be taken. Trying to squeeze prices? By accident I saw some cheap concrete being mixed. I lost some (more) hair that day. All the locals have subsequently warned me only to order from that person when the quality doesn't matter This board is full of people who have forgotten more than I'll ever know about the subject. But one thing is sure. Concrete is fascinating. Really fascinating. Link to comment Share on other sites More sharing options...
Vijay Posted June 9, 2017 Author Share Posted June 9, 2017 1 hour ago, Temp said: Ask the person who specified that why it's so difficult to find and can it be relaxed. Yes 32/40 relates to the strength. http://www.grabtrucks.com/ready-mix-concrete/mix-design/ Ask if it's essential the stone be <10mm. I'm not sure I would rely on concrete being waterproof but perhaps you are adding braces to your belt. Thanks for that link, really helpful! The mix is specific so it falls into the ICF properly and sets at the right rate, so not to cause bursts. Link to comment Share on other sites More sharing options...
Vijay Posted June 9, 2017 Author Share Posted June 9, 2017 17 minutes ago, recoveringacademic said: @Vijay, I have learned one thing about concrete: what is specified is often not what gets delivered. I say this on the basis of about five deliveries (or so), and having bought several lots of cheap concrete from a lets say 'informal' supplier. Our main builder explained that, unless you know the production and delivery companies - the real people on the end of a phone - then you are likely to get generally strong concrete, or middling concrete or weak concrete. Here are a few factors affecting what actually gets delivered How do you know you arent getting the tail end of someone else's delivery - to a different spec - topped up with your spec? How well do you know the company dispatcher (for the lorries)? Not at all? He'll smell it and might well take advantage of that Is the concrete going to be pumped? If so more cement is added to make it 'slippier' in the pipes Is the concrete going to be tested? If not, lie and tell everyone that samples will be taken. Trying to squeeze prices? By accident I saw some cheap concrete being mixed. I lost some (more) hair that day. All the locals have subsequently warned me only to order from that person when the quality doesn't matter This board is full of people who have forgotten more than I'll ever know about the subject. But one thing is sure. Concrete is fascinating. Really fascinating. From my foundation pour I would agree with you and the pump bloke was really annoying with wanting to add more water to things. It was a smaller company and they really want my ICF concrete business, so are working to get it right. I've already warned them that any tickets for wrong concrete will be turned away and I will have a slump cone for random tests Link to comment Share on other sites More sharing options...
jamiehamy Posted June 9, 2017 Share Posted June 9, 2017 23 minutes ago, recoveringacademic said: @Vijay Is the concrete going to be pumped? If so more cement is added to make it 'slippier' in the pipes Sand... Oversanded mix for pump... which in turn needs more cement 1 Link to comment Share on other sites More sharing options...
Vijay Posted June 9, 2017 Author Share Posted June 9, 2017 12 minutes ago, jamiehamy said: Sand... Oversanded mix for pump... which in turn needs more cement Hello mate - was it you pumping up the hill then?? Link to comment Share on other sites More sharing options...
Vijay Posted June 9, 2017 Author Share Posted June 9, 2017 The link Temp gave shows that the 40 in the RC 32/40 refers to 40 Newton/28 day strength, but any idea what the 32 is? Link to comment Share on other sites More sharing options...
jamiehamy Posted June 9, 2017 Share Posted June 9, 2017 9 minutes ago, Vijay said: Hello mate - was it you pumping up the hill then?? It was - I'll check the paperwork when I get home but think we ended up with a 120mm slump, but that was for running through a two inch line pump over 35metres. 90mm should be fine for a boom. Link to comment Share on other sites More sharing options...
Vijay Posted June 9, 2017 Author Share Posted June 9, 2017 That's why I knew it must of been you, Alan mentioned pumping through a 2" line pump Link to comment Share on other sites More sharing options...
PeterW Posted June 9, 2017 Share Posted June 9, 2017 10mm is pump grade - anything bigger and the pump guy may hate you.... sanded and extra cement to make it flow. And I've never heard of concrete being certified waterproof without an additive. Small price to pay it is wrong ... Link to comment Share on other sites More sharing options...
Vijay Posted June 9, 2017 Author Share Posted June 9, 2017 22 minutes ago, PeterW said: 10mm is pump grade - anything bigger and the pump guy may hate you.... sanded and extra cement to make it flow. And I've never heard of concrete being certified waterproof without an additive. Small price to pay it is wrong ... Is that 100% right? The only reason I ask is the concrete supplier who was originally gonna supply my foundation concrete who knew it was gonna be pumped, has said he cannot do the ICF mix as he doesn't supply concrete with 10mm aggregate. Small price to pay - is that said with a touch of sarcasm???? Link to comment Share on other sites More sharing options...
Alexphd1 Posted June 9, 2017 Share Posted June 9, 2017 Think we used r35 120mm sump through the boom (can't remember the aggregate but 10mm rings a bell). Maybe slightly of topic but we have used 3 different pumps from 3 different companies at various stages. The best one was a 35m boom from a national company due to them having a shut of valve at the end of the boom so it was very quick to stop which was a major help for running up the gables. They also had the smallest nozzle for easiest control. Link to comment Share on other sites More sharing options...
Vijay Posted June 9, 2017 Author Share Posted June 9, 2017 So yours was an ICF build Alex? I'm pretty certain I'm going to need a larger boom pump too Link to comment Share on other sites More sharing options...
jamiehamy Posted June 9, 2017 Share Posted June 9, 2017 The 'R' doesn't mean it will have rebar - as long as you give the prescribed spec, they will worry about how to make it up. Interested in the water proof concrete part tho - why is this needed? If it's below DPC there is no reason for it that I'm aware of but would be interested to know if there is a specific reason?. Link to comment Share on other sites More sharing options...
Alexphd1 Posted June 9, 2017 Share Posted June 9, 2017 Yep. Nudara icf. Learned on job from rebar to concrete it was a real learning curve. Made a few mistakes but will be doing a eps passive slab and icf again on second build so pretty happy with build up to now. Was meant type c35 concrete not r35. I think waterproof additive to concrete is more for used for basements constructed with icf but biggest problem I see with this is the concrete sealing around the plastic ties but that is a other topic. I am a bit wary of your 80mm sump, who has spec'd that? How high are you pouring? Link to comment Share on other sites More sharing options...
Vijay Posted June 9, 2017 Author Share Posted June 9, 2017 38 minutes ago, jamiehamy said: The 'R' doesn't mean it will have rebar - as long as you give the prescribed spec, they will worry about how to make it up. Interested in the water proof concrete part tho - why is this needed? If it's below DPC there is no reason for it that I'm aware of but would be interested to know if there is a specific reason?. Yeah, it's for up to DPC. Link to comment Share on other sites More sharing options...
Vijay Posted June 9, 2017 Author Share Posted June 9, 2017 30 minutes ago, Alexphd1 said: Yep. Nudara icf. Learned on job from rebar to concrete it was a real learning curve. Made a few mistakes but will be doing a eps passive slab and icf again on second build so pretty happy with build up to now. Was meant type c35 concrete not r35. I think waterproof additive to concrete is more for used for basements constructed with icf but biggest problem I see with this is the concrete sealing around the plastic ties but that is a other topic. I am a bit wary of your 80mm sump, who has spec'd that? How high are you pouring? 80mm slump was quoted by Polarwall. Height will be up to and including gables but obviously separated at each floor Link to comment Share on other sites More sharing options...
Alexphd1 Posted June 9, 2017 Share Posted June 9, 2017 Are you using a poker? Link to comment Share on other sites More sharing options...
Vijay Posted June 9, 2017 Author Share Posted June 9, 2017 was told not to Link to comment Share on other sites More sharing options...
Alexphd1 Posted June 9, 2017 Share Posted June 9, 2017 Obviously go with what the manufacturer says but the three icf manufacturers I looked at in detail was nudara, quadlock and amvic. They all quoted sump between 120-150mm and use a poker especially around rebar (on second thoughts can't remember if amvic quoted a poker) . Link to comment Share on other sites More sharing options...
jamiehamy Posted June 10, 2017 Share Posted June 10, 2017 9 hours ago, Vijay said: Yeah, it's for up to DPC. My point is - why? Additives are expensive and I don't see what benefit there is. The footings are not 'waterproof' are they? Link to comment Share on other sites More sharing options...
Vijay Posted June 10, 2017 Author Share Posted June 10, 2017 But we need need some sort of damp proofing to stop rising damp even with ICF don't we? Obviously I wouldn't want to pay for the crazy price of a waterproof additive and was told that just having a minimum cement content of 325kg pcm and water cement ratio of 0.5 will give me a waterproof concrete. Link to comment Share on other sites More sharing options...
Alexphd1 Posted June 10, 2017 Share Posted June 10, 2017 A dpm (damp proof membrane) . Our was laid on the first 100mm of eps slab then the extra 200mm eps layer on top. Link to comment Share on other sites More sharing options...
Vijay Posted June 10, 2017 Author Share Posted June 10, 2017 But did you build your ICF off your concrete slab? I've got B&B floor and strip foundations. I still use a DPM but have to stop rising damp in the concrete core of the ICF http://www.polarwall.co.uk/pdf/PWD014.pdf Link to comment Share on other sites More sharing options...
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