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#1 2008-10-28 18:37:13

mat
Member
Registered: 2008-10-28
Posts: 1

how to make concrete

hello I have to make a concrete base in metres cubed total 1.68 metres cubed.
The ratio to concrete is 1 part cement to 2 parts sand and 3 parts gravel.
how much cement,gravel, and sand in kilograms?

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#2 2008-10-29 00:35:22

mathsyperson
Moderator
Registered: 2005-06-22
Posts: 4,900

Re: how to make concrete

From that information, you can only work out how much of each material to use, in quantities of m³.

Scale the ratio so that all of its parts add to 1.
They currently add to 6, so you do this by dividing them all by 6.

Now you have 1/6 cement, 2/6 sand and 3/6 gravel in your mix.

Therefore, you use 1/6 * 1.68 = 0.28 m³ of cement, and similarly you use 0.56 m³ of sand and 0.84 m³ of gravel.

To convert those amounts into kg, you'd need to know the densities of each material.
ie. how heavy is 1m³ of the stuff?


Why did the vector cross the road?
It wanted to be normal.

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