# Concrete Calculation questions

Discussion in 'Building' started by 600rob, 4 Sep 2016.

1. ### 600rob

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Im trying to calculate the amount of concrete by weight that i will need for a small job and have some questions that you guys might be able help and advise with.

1. from what Ive researched, 1 cubic meter of concrete weighs approximately
2,406 kg.
Does this figure refer to the concrete in its mixed form ready to use?
(i.e all components including water added and mixed up)

2. Based on the above being correct can you advise me if ive got the following calculation correct:

I have a space measuring 30cm long x 40cm wide X 40 cm deep.

0.3 x 0.4 x 0.4 = 0.048 cubic metres

2406 x 0.048 = 115.48 Kg of mixed concrete

If the base calculation is correct I will adjust it, adding 5-10% to cover any discrepancies with measurements/mixing and spillages etc.

Rob

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4. ### ^woody^

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More to the point, does anyone sell it by weight?

5. ### 600rob

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Not exactly but I'll be buying the bags of cenent, sand and aggregate from b n q or somewhere similar so yes I'll ultimately be able to work out the weight based on the bag weights.

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7. ### ^woody^

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And when you put your 25kg bag in the mixer and add your cement and water, how much concrete will come out in weight?

8. ### 600rob

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Cement weight + aggregate weight + water weight.

I forgot to add. 1litre of Water = 1 kg

10. ### noseall

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By weight????

11. ### tomfe

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I'd just get a bag of cement and 6 bags of ballast.

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13. ### ^woody^

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Yeah, think about the size of a bag of sand/gravel and how many would fit in that space. 5? 6?

The cement and water adds to the weight but not to the volume

14. ### kazuya

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15kg of cement, 30kg of sand, 56kg of gravel and 14 litres of water

• Thanks x 1
15. ### 600rob

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Cheers buddy!

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