Calculating Density of Concrete

[SiCharlton]

Hi all,
My problem is concerning density and how to calculate it. Basically, calculating density of a concrete cube. I've been given;

Weight (kg) In Air - 2.345,2.340
In Water - 1.348, 1.360

Dimensions - Height - 1900mm
Width - 320mm
Depth - 180mm

I need to calculate the Density kg/m^3

Does it include the specific gravity etc..? I've searched google for ages but to no avail. Could it be, Weight in air/(weight in air - weight in water) to give S.G, thus 2.35...therefore a ratio 1:2.35 of water to cement. Taking density of water as 1000kg/m^3, density of concrete is 2350kg/m^3?

Any help will be really appreciated.

Thanks
Simon

 

[mgb_phys]

You seem to have been given rather too much information. If you have the dimensions and the weight in air then you have the density ( simply mass / volume )
Be carefull of the units.

If you wanted to be really picky you could include the bouyant effects of the air - although this wouldn't be worth it given the accuracy the dimensions are quoted to.

 

[Moetasim]

Hello Simon,

Calculating the density of concrete involves a few simple steps. First, we need to understand what density is. Density is the measure of how much mass is contained in a given volume of a substance. In this case, we are looking at the density of concrete, which is a mixture of cement, water, and aggregates such as sand and gravel.

To calculate the density of your concrete cube, we will need to use the formula: Density = Mass/Volume. In this case, the mass is the weight of the cube, and the volume is the dimensions of the cube.

Using the given information, we can calculate the volume of the cube by multiplying the height, width, and depth together. So, in this case, the volume would be 1900mm x 320mm x 180mm = 109440000 mm^3.

Next, we need to convert the units of the weight from kg to g, as the units of density are typically in g/cm^3 or kg/m^3. So, the weight in air would be 2345 g and in water would be 1348 g.

Now, we can plug in the values into the formula: Density = 2345 g / 109440000 mm^3 = 0.0214 g/mm^3. This is the density of the concrete in g/mm^3.

To convert this to kg/m^3, we need to multiply by 1000000 to convert g to kg and by 1000 to convert mm^3 to m^3. So, the density of the concrete would be 21.4 kg/m^3.

This is the density of the concrete without taking into account the specific gravity. If you would like to include the specific gravity, you can use the formula you mentioned: Weight in air / (weight in air - weight in water). So, in this case, it would be 2345 g / (2345 g - 1348 g) = 2.35. This means that for every 1 kg of water, there is 2.35 kg of cement in the concrete mixture.

I hope this helps with your calculations. Keep in mind that the density of concrete can vary depending on the specific mixture and composition, so this may not be an exact value. If you need a more accurate density, I would suggest consulting a concrete expert. Good luck with your project!