Concrete Blocks - N/mm² and kN

[darudey]

Could someone help me clear the confusion between these two units when ordering concrete blocks?

I have been asked to place an order for 100 x 440 x 215mm 3.6kN blocks for inner skin, but in most stores, I could only find references to 3.6N/mm².

See buildbase link: https://www.buildbase.co.uk/concrete-blocks-100010511-0000?filter={%22density%22:[%223.6%22]}

However, on Google, I find other references where they use 3.6kN/m²
http://www.wightbuildingmaterials.com/product/concrete-blocks/

Forgive me if I'm wrong.... 3.6N/mm² is not the same as 3.6kN/m² or 3.6kN right? Or are they units for different things?

Looking forward to the helpful responses.

 

[Paulg31]

It’ll be 3.6 N/mm2 you should be looking for. It’s the compressive strength of the block. I think whoever asked you to make the order got his units mixed up.

 

[darudey]

Thanks Paulg31, so kN is not a valid unit when it comes to concrete blocks specifications?

And would you say, the 3.6kN/m² unit used in the wightbuildingmaterials link above, is wrong?

 

[John D v2.0]

3.6kN/M2 would be extremely poor. Even wet clay is far better.
3.6kN isn't the right units.
3.6N or 3.6N/mm2 is the standard common lightweight block. The other common one is 7N concrete heavy block.

 

[cjard]

given that there are a million mm2 in a m2, 3.6kN/m2 is 3.6 thousand newtons per million mm2.

This is clearly much less strong than 3.6 million newtons per million mm2 (3.6 newtons per mm2)

The sites that are citing 3.6kN/m2 have their units wrong

Perhaps more important is the type of block you'll order, when considering how well insulated the wall needs to be to meet regs; dense concrete blocks are less thermally efficient than aerated concrete, and wil lrequire more thermal insulation material to achieve your target U value. Personally, having handled both, if 3.6N was specified I'd get the aerated blocks..

 

[^woody^]

3.6 are standard for internal skin. But you need to be clear on the thermal qualities required, as there are standard concrete and more efficient blocks suck as thermalite, celcon or quinlite for instance.