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Concrete base cost , any idea ?


fenboy
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I am intending building a new double kennel and runs in the next few months , my current one is slabbed but from a hygiene point of view I am going to want to lay a concrete base in the new accommodation .

 

Can anyone tell me what sort of cost will be involved on a base of 12' x 11' and around 5" deep ?

 

I am thinking of ready mixed .

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Pre-mix and ready mix? Likely nothing, just the name.

 

1.5m^3 is an awkward amount. Between a tiny amount and a decent load. You might get a good price if you take the end of a delivery elsewhere. Short notice, need retarding additive might be downsides.

 

20N/mm^2 is plenty strong enough for that duty. The dry mix merchants which mix on site are likely the most accommodating for thaf size job. Damned annoying if you need just a little extra.....

 

Footings in the fens might be the most important part of the job!

 

RAB

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Have a look at Ageila concrete. It's more expensive but has a smooth glass like finish, that will clean easy.

Lafarge do it.

 

Thanks but I am planning on a finish on top of the concrete , which requires a brushed finish to adhere to.

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a mini load will cost delivered and you shift it £250 upwards. mix and barrow where someone else does it is 22 barrows to the metre cube and about £150 a metre

 

to mix it your sef its £40 for the builders bag of ballest and £60 for the cement so we say a rough £100 per bag and you will need three bags

 

its a case of do you waant to do the work or get someone else to do it, personally i prefer to watch someone else do the hard work with concrete

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Thanks but I am planning on a finish on top of the concrete , which requires a brushed finish to adhere to.

Either paint it with an epoxy paint or lay a porcelain tile over the top. Any othe way is useless in my opinion. Paint flakes and anything else absorbs urine and smells.

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100mm deep on a well consolidated base would be plenty..a 1:4 all in mix will give you 25+ N/mm2 at 28 days... I cant imagine a kennel construction is going to impose anywhere near that sort of load on the base.

 

If you do it 100 deep at 1:4 you will need 1.01m3 of all in aggregate, this is sold in tonne bags which are actually 855 kg and equates to about 0.6m3 per bag so you would need 2 and have about .20m3 left over. These would be about £50 including VAT delivered from Travis or similar.

 

Mixed at 1:4 you would need .370 KG of OPC or 15 Bags. This would be about £4.08 per bag incl.Vat

 

All in Ballast £ 100.00

Cement £ 61.20

Labour £ ?

 

If you want to make a decent job of it substitute the all in ballast for concreting sand ( more or less the same cost) and trowel the surface smooth ( don't mix it up too wet or it will shrink and crack ) Cover it with polythene and let it cure for at least 14 days (preferably a month) and then paint the dry surface with waterproofing concrete sealer.

 

Don't forget to lay to a slight fall front to back so the water doesn't pool.

Edited by Fisherman Mike
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Do not go only 50mm thickness of concrete on a ballast base of that size. It will likely crack. Especially in the fens - think here Thorney golf course?

 

4:1 mix will exceed 40 Newtons or more at 28 days (dependent on aggregate), I would think. Unless you used masonry cement or a low strength fly-ash product.

 

4:2:1 (large aggregate to sand to cement) at 0.5 water/cement ratio was the standard testing mix for cement testing when I worked in the industry. We did use granite aggregate and a well proportioned fine aggregate grading (silica sand of various particle sizes). We aimed for about 40 Newtons per square millimetre at 28 days back then. Not up to date with current targets.

 

But better to use more cementitious content for durability, than going 8:1 or leaner, for a simple strength specification.

 

RAB

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100mm deep on a well consolidated base would be plenty..a 1:4 all in mix will give you 25+ N/mm2 at 28 days... I cant imagine a kennel construction is going to impose anywhere near that sort of load on the base.

 

If you do it 100 deep at 1:4 you will need 1.01m3 of all in aggregate, this is sold in tonne bags which are actually 855 kg and equates to about 0.6m3 per bag so you would need 2 and have about .20m3 left over. These would be about £50 including VAT delivered from Travis or similar.

 

Mixed at 1:4 you would need .370 KG of OPC or 15 Bags. This would be about £4.08 per bag incl.Vat

 

All in Ballast £ 100.00

Cement £ 61.20

Labour £ ?

 

If you want to make a decent job of it substitute the all in ballast for concreting sand ( more or less the same cost) and trowel the surface smooth ( don't mix it up too wet or it will shrink and crack ) Cover it with polythene and let it cure for at least 14 days (preferably a month) and then paint the dry surface with waterproofing concrete sealer.

 

Don't forget to lay to a slight fall front to back so the water doesn't pool.

You cannot just use Sharp sand (concrete sand) for anything over 50 mm thick, anything greater than 50 mm requires aggregate & the minimum thickness of any slab on the ground should be at least 100 mm.

 

<50 mm: finer range of Type C or coarser range of Type M sand

>50 mm: Sharp sand + 6 mm to 10 mm aggregate at a 1:3:1 (Cement : fine aggregate : sharp sand)ratio which is your traditional 1 to 4 mix.

>100 mm: the aggregate is 6 mm to 20 mm.

 

Also the above calculations are with CEM I 42.5 N (traditional OPC). Trying to get 25 kg bags of CEM I 42,5 N is going to be next to impossible, only really available in bulk buy or bags of white CEM I 52.5N, so you are looking at a CEM II in 25 kg bags. With a CEM II the mix proportions are going to be altered depending on the rating. For example, a cement of strength class CEM II 32,5 N and would probably require an increase in cement content of about 10 % but it will still be bagged and sold as premium cement.

 

An additional period of curing could be necessary as well with CEM II regardless of strength class.

If laying on the ground you should definitely consider air entrainment to protect against freeze thaw as well.

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You cannot just use Sharp sand (concrete sand) for anything over 50 mm thick, anything greater than 50 mm requires aggregate & the minimum thickness of any slab on the ground should be at least 100 mm.

 

<50 mm: finer range of Type C or coarser range of Type M sand

>50 mm: Sharp sand + 6 mm to 10 mm aggregate at a 1:3:1 (Cement : fine aggregate : sharp sand)ratio which is your traditional 1 to 4 mix.

>100 mm: the aggregate is 6 mm to 20 mm.

 

Also the above calculations are with CEM I 42.5 N (traditional OPC). Trying to get 25 kg bags of CEM I 42,5 N is going to be next to impossible, only really available in bulk buy or bags of white CEM I 52.5N, so you are looking at a CEM II in 25 kg bags. With a CEM II the mix proportions are going to be altered depending on the rating. For example, a cement of strength class CEM II 32,5 N and would probably require an increase in cement content of about 10 % but it will still be bagged and sold as premium cement.

 

An additional period of curing could be necessary as well with CEM II regardless of strength class.

If laying on the ground you should definitely consider air entrainment to protect against freeze thaw as well.

With respect we are talking about a kennel slab in a back garden here not an insitu concrete carpark deck.

 

100 mm all in or concreting sand at 1:4 will be fine. ( as long as the base is well consolidated. ) chuck in a layer of A142 if worried about cracking or sinking.

 

I can pick up a 25KG back of OPC at any decent builders Merchant...what you on about ? :whistling:

 

No need to over complicate matters...like I said 1:4 all in aggregate or concreting sand and OPC will do the job at 100mm thick and it will cost you sub £175 all up.

 

Its not Rocket science. :lol:

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With respect we are talking about a kennel slab in a back garden here not an insitu concrete carpark deck.

 

100 mm all in or concreting sand at 1:4 will be fine. ( as long as the base is well consolidated. ) chuck in a layer of A142 if worried about cracking or sinking.

 

I can pick up a 25KG back of OPC at any decent builders Merchant...what you on about ? :whistling:

 

No need to over complicate matters...like I said 1:4 all in aggregate or concreting sand and OPC will do the job at 100mm thick and it will cost you sub £175 all up.

 

Its not Rocket science. :lol:

 

With respect it is not the strength that’s the major problem with 100 mm screed made with just sand and no graded aggregate.

You will have too higher water cement ratio and the chances of shrinkage and cracking are GREATLY increased. Please don’t suggest curing longer will totally elevate this as it doesn’t.

 

BS 8204 1:2003+A1:2009 ‘Screeds, Bases and in situ flooring’ goes into it in detail, Clause 7.5.1 if you’re interested. What you are suggesting is against the specification regardless of strength required, car park or dog kennel, it makes NO distinction, the chances of cracking and shrinking are greatly increased over 50 mm without graded coarse aggregate. If you are going to specify something and try to look as if you know what you are saying then at least give a nod to the British Standards not go against them. You might as well have some bloke in the pub saying use 20 to 1 with fine sand from the beach it might work, it's only a dog kennel.

 

It’s also not structural for external use below ground so will not withstand freeze thaw and susceptible to break up even if you never walk on it.

What you suggested in your post was that a 100 mm screed made with just sand is better than 100 mm concrete made with aggregate at below ground level. It’s NOT it’s the other way around, that’s not just my opinion working in a construction materials testing lab it’s also the opinion of the all the relevant British Standards on the subject.

 

That is what I was correcting you on just in case someone took your advice.

Going against the standards does not mean it will automatically fail but it does greatly increase the chances of failure and 100 mm plus with just sand and no coarse aggregate is asking for trouble. I have investigated enough floor screed failures where this has been the problem and it is classed as a screed not fine concrete without coarse aggregate. Admittedly I have never tested an outside floor screed designed as a ground slab before as no one has been stupid enough to specify one yet.

 

As regards the cement in 25kg bags if you would kindly show me a link to CEM I 42.5N (which is OPC) and not a CEM II (which is OPC + 35% filler) in 25 kg bags, either by a UK manufacturer or builders yard I will stand corrected on that one, but you’re going to struggle if it’s made by Lafarge or one of its subsidiaries or using Travis Perkins and the likes.

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With respect it is not the strength that’s the major problem with 100 mm screed made with just sand and no graded aggregate.

You will have too higher water cement ratio and the chances of shrinkage and cracking are GREATLY increased. Please don’t suggest curing longer will totally elevate this as it doesn’t.

 

BS 8204 1:2003+A1:2009 ‘Screeds, Bases and in situ flooring’ goes into it in detail, Clause 7.5.1 if you’re interested. What you are suggesting is against the specification regardless of strength required, car park or dog kennel, it makes NO distinction, the chances of cracking and shrinking are greatly increased over 50 mm without graded coarse aggregate. If you are going to specify something and try to look as if you know what you are saying then at least give a nod to the British Standards not go against them. You might as well have some bloke in the pub saying use 20 to 1 with fine sand from the beach it might work, it's only a dog kennel.

 

It’s also not structural for external use below ground so will not withstand freeze thaw and susceptible to break up even if you never walk on it.

What you suggested in your post was that a 100 mm screed made with just sand is better than 100 mm concrete made with aggregate at below ground level. It’s NOT it’s the other way around, that’s not just my opinion working in a construction materials testing lab it’s also the opinion of the all the relevant British Standards on the subject.

 

That is what I was correcting you on just in case someone took your advice.

Going against the standards does not mean it will automatically fail but it does greatly increase the chances of failure and 100 mm plus with just sand and no coarse aggregate is asking for trouble. I have investigated enough floor screed failures where this has been the problem and it is classed as a screed not fine concrete without coarse aggregate. Admittedly I have never tested an outside floor screed designed as a ground slab before as no one has been stupid enough to specify one yet.

 

As regards the cement in 25kg bags if you would kindly show me a link to CEM I 42.5N (which is OPC) and not a CEM II (which is OPC + 35% filler) in 25 kg bags, either by a UK manufacturer or builders yard I will stand corrected on that one, but you’re going to struggle if it’s made by Lafarge or one of its subsidiaries or using Travis Perkins and the likes.

I bow to your superior knowledge of interior domestic screeds but to be blunt I've forgotten more about BS 8500 than most people will ever know.. I must have specified and purchased over a half a million cubic metres of premixed concrete and screed in the last 40 years as well, so I think I'm qualified to post a little bit about it.

 

I never raised an issue with Cem I or II OPC.... you did.! its just totally unnecessary for this situation. OPC is available in 25 KG bags at any Builders Merchant in the world.

 

Like I said 1:4 all in, or concreting sand at 1:4 on a well consolidated hardcore bed will do the job ( in my experience ) Just don't make the mix too wet or it will shrink as it cures. Also I never suggested a 100mm concreting sand mix would be better at all.

 

This is a simple garden slab and you have completely missed the point.

 

Just by a couple of tonne bags of aggregate and cement and get it laid ...then Timps can come around and wave his willy at it, dip it in and test it. :lol:

 

I've answered the OPs question £175 tops. WE are making a mountain out of a mole hill....RC 35, Air entrained, what next caltite to keep the dog **** out.?

 

By the way I have a 18 year old 100mm concrete screed in my back garden which I mixed myself....its still as good today as it was then, albeit its reinforced with 2 layers of chicken wire.

 

back at ya :lol:bye2.gif.pagespeed.ce.-b_0gAl0t0.gif

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