What cost for C35 blinding layer?

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Hi All,

I am having some pile work done (the constructive variety, but still painful financially) and the piling contractor indicates that I need to get a 50mm thick C35 concrete blinding layer prior to them starting with piling with raft.

The area to be covered is 5.6 x 11.2m so approx 3.2m3 in total I think.

I'll have to get a groundsman to do this, but what are the current rates for C35 and what would a groundsman typically charge to complete the job? I've previously had other ridiculous quotes and I am extra wary this time round.

let's assume the ground has been set out and levelled, ready for pour.

I am based in the SE (Kent).

Thanks.
 
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I can't for the life of me think why you would need to use C35 as a blinding layer...C10 is perfectly adequate for blinding.
 
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How much cheaper is C10?

I'm only going by what they have specified and I'm pretty sure they would go for C10 if they could. I'm responsible for getting the blinding layer done so they have no commercial advantage in speccing C35 over C10.

Probably speccing for C35 since their piling rig will be maneuvering on top.
 
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I don't know why they would specify C35 for blinding, but would be interested if anyone here knows if there is a logical reason.

There would be no advantage in specifying C35 as a capping for the piling mat. A piling mat does not need a concrete capping as long as it is a sufficiently thick, well compacted granular material. If it isn't thick enough and well enough compacted, C35 will crack just as quickly as C10 as both have negligible tensile strength.

C35 is usually reserved for reinforced concrete and not for blinding or mass concrete situations.

Not sure of the difference in cost tbh - some of the builders will know more - but there will definitely be a saving.
 
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I have just payed £135/m for some mix on site c35 concrete in Hampshire. had i needed more than 1.5m i am sure it would have been a better price. For comparison it was going to be £125/m for standard c20.
 
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As above C35 grade concrete sounds a bit over the top of a piling mat or blinding layer for a piled raft. The actual raft could be reinforced C35 concrete. Quite often piling mats are just made up of 6f2 you'd want far more than 50 mm for that though. C10 would be fine for blinding.
 
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There would be no advantage in specifying C35 as a capping for the piling mat. A piling mat does not need a concrete capping as long as it is a sufficiently thick, well compacted granular material. If it isn't thick enough and well enough compacted, C35 will crack just as quickly as C10 as both have negligible tensile strength.

Thanks all for your comments. Along the lines of Ronny, spoken to another piling firm and they have stated that they can work from a layer of compacted rubble. That should save me a few pennies. I have plenty of rubble from my block walls and chimney stacks. What kind of figure should I be looking at to get someone in to crush and lay a 5.6 x 11.2m top?

Thanks!
 

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