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Which concrete, from where, with what admixture?
Waterproof concrete has
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enough sand to fill all the spaces between the stones
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enough cement to fill all the spaces between each grain of cement
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sufficient water to set the concrete properly without pushing the grains of cement apart with water that will be left over.
But this will be too stiff to pump and too stiff to fully compact.
It also needs a powerful water reducing plasticiser to increase its workability without more water.
But, the big problem is, the big boys like Cemex and Heidleberg have all let me down many times.
The little boys, such as volumetric mixer trucks and drum trucks that go anywhere to buy concrete, are hopelessly poor on quality and cannot dose any admixture properly.
And the admixture suppliers all cheated when they got their BBA certificates, none of which prove they made a non-waterproof concrete mix waterproof (used beneath ground where it will not fully dry out).
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If I add my powerful water-reducing plasticiser to your concrete at site, I accepted the concrete recipe and I guarantee your basement will have no visible ingress of water through your waterproof concrete structure - or else I will help you fix your leaks for free.
No self-builder had a leak I needed to fix since 2013. I supervise your concreting and that makes as much difference as my powder.
Volumetric mixers cannot make waterproof concrete.
Some drum-truck readymix suppliers, such as Hanson, Heidelberg, Cemex, Breedon, Aggregate Industrie, London Concrete, Coppard, Gallagher, Euromix, Brett, can make waterproof concrete. But too many of their batchers get the mix badly wrong and their trucks get stuck in traffic; and some send you too much concrete too soon.
Preferably, therefore, try to use Mixamate. Mixamate weigh batch accurately at site and pump your fresh concrete with the same truck. I go into a lot more detail about the priceless benefits of Mixamate here.
If you choose a drum truck supplier, you need to ask for
P350
Over-sanded for pumping
Target slump at site 60mm
No additives of their own
and it may be easier to ask them to ask their technical manager to speak to me. We will have spoken before, probably.
Make sure Sales understand the slump will be increased at site when a powerful plasticiser is added and mixed in 6 revolutions per cubic metre.
It can be beneficial if OPC is blended with some alternative because it lowers the curing temperature, although it also slows the strengthening time.
But too much alternative robs the OPC of alkalinity.
Lime should be limited to 20%; Flyash to 35%; and GGBS to 50%. (From BS 8007)
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Your concrete needs to be weigh batched. Volumetric trucks are not accurate or consistent enough.
Ask them to talk to me, Phil Sacre 07773 377087 about any concerns. I have probably spoken to their technical manager before.
If you buy my goods and supervision I give you a free guarantee to help you fix all your structure's leaks. You do the chiselling. i fix the leaks.
But no self builder's basement has leaked since 2013. Which is better still.
You can open and save the material safety data sheet for my powder here.
Understand more about waterproof concrete and suppliers who allege they sell it.
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Science lessons.
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Much more from the text books.
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The scandals of BBA certification..
Back to the Basement Building Questions Answered menu.
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Forward to the Basement Building Construction Manual menu.
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For a fixed fee of £199 I will answer all your questions by email. More details here.
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