For modern construction of any scale, cement-sand mixtures are practically an alternative category of materials. When combining cement powder with a number of components that complement it, workers get a certain type of mortar. The key problem with the use of cement in bags is that the mixing proportions are indicated in the proportion or volume content, and the delivered packages are indicated in the weight content.

It is not advisable to buy 50 kilograms of a viscous substance (it is 50 kg of cement that is packed by manufacturers), but at the same time, a smaller bag of cement may not allow you to create an effective mixture. Regardless of the conditions of long-term storage, the powder will lose its strength qualities, and therefore it is best for the developer to know how much cement is in the bag. Read the articles on our website to learn about this and other nuances of using dry assembly and construction mixes.

## Amount of cement in a bag

The difficulty is to perform a mathematical calculation of the volume of a 50 kg bag of cement (25; 40).

- The powder is a mixed mass of elements of different structures, which naturally affects the density of cement. In turn, this parameter affects the fact that the same weight of a bag of cement may differ in cubic (volume) terms.
- It is also worth noting that the density of the binder powder changes over time. It has the lowest value in the freshly filled state, because its particles are charged and capture air, but during transportation, ramming occurs – the density increases.

When estimating the cubic dimensions of a 50 kg bag of cement, an average figure called “specific gravity”is taken into account. For example, the popular Portland cement has a specific density of 1300 kg per ^{m3} . The formula for calculating the volume of cement is quite simple:

- If 1300 kg / cubic meter is 100%, then 50 kg in a bag is X%.
- In this case, X = 50*100/1300 = 3.85%.
- Accordingly, fifty kilograms is 3.85% of a cubic meter of powder or 0.0385 cubic meters of cement.

Of course, for a 25 kg bag of cement, you can divide the volume contained in a 50 kg bag in two, but for a 40 kg bag, you will have to do all the mathematical work again. To avoid having to re-list your expenses every time, use the summary table that lists popular astringent powders with different specific densities.

Type of cement | Specific gravity, kg / m3 | Contents in a bag of cement cubes | ||

25 kg | 40 kg | 50 kg | ||

pk | 1200-1300 | 0,019 | 0,031 | 0,0385 |

ŠPC | 1100-1250 | 0,02 | 0,032 | 0,04 |

SSHPC | 1000-1200 | 0,023 | 0,036 | 0,045 |

Checkpoint | 850-1150 | 0,025 | 0,04 | 0,05 |

SSPC | 800-1100 | 0,026 | 0,042 | 0,053 |

If you do not trust the tabular data, or those indicated on the powder bag, recalculate and make sure that the volume of the cement bag is correct. For this:

- Take one liter container and pour the resulting substance.
- Weigh everything in this form (without ramming or shaking).
- Subtract the tare weight from the available number.
- This results in a number corresponding to the actual weight of a liter of powder.
- Multiply this indicator by 1000.

So you will have correctly calculated the bulk density of the powder. Further calculations can be performed with this indicator.