Bulk density - how to define it?

The bulk density of the material is the ratio of the mass of this substance in the freshly spilled state to its volume. This takes into account both the volume of the substance itself, and the volume of voids inside it and the volume between individual particles (for example, in coal). For obvious reasons, this kind of density is less than the true density, which excludes the above-mentioned voids.

To determine the bulk density, tools such as a scale, a ruler, the "Funnel standard" device, a measured vessel of a certain volume are used. Bulk density of a substance is determined for a material with a certain moisture content. If the sample does not meet the requirements of humidity, then it is moistened or, more often, dried.

When we determine what the bulk density of sand is, the algorithm of actions should be as follows:

1. The measuring vessel is weighed and installed under a standard funnel (it has a shutter from below).

2. The sand is poured into the funnel, after which the bolt is opened so that the sand instantly pours out into the measuring vessel, fills it and forms a hill from above.

3. Excess sand is "cut off" by a ruler by movement on top of a measuring vessel.

4. The vessel with sand is weighed, the weight of the vessel itself is subtracted from the total mass.

5. The bulk density is calculated.

6. The experiment is repeated 2-3 times, after which the average value is calculated.

In addition to the density in the loose state, the density in the compacted version is measured. To do this, the sand in the vessel is rammed a little on the vibratory pad for 0.5-1 minutes. Calculate the bulk density of cement, you can by the same method.

In accordance with GOST 10832-2009, sand of a certain type (expanded) in bulk density is divided into certain grades - from M75 (density index is 75 kg / m3) to M500 (density 400-500 kg / m3). To be assigned to a particular brand, sand must have a certain thermal conductivity and strength when squeezing. For example, the thermal conductivity of the M75 brand at a temperature of 25 C + -5 C should not be more than 0.043 W / m 3 C. And the compressive strength for M500 sand is defined as 0.6 mPa (not less). Sand of quartz type (moisture content of 5%) has a bulk density of 1500. For cement, this figure is about 1200 kg / m3 in free-flowing condition and about 1600 kg / m3 in the state of compaction. Often, an average figure of 1300 kg / cubic meter is used for calculations.

Why do we need bulk density? The fact is that in trade turnover this value is used, and not the true density (for example, if sand is sold in bags). Therefore, in order to translate prices per cubic meter into prices per tonne, you just need to know what is the density of the material. In addition, for the preparation of mortars may require bulk or weight data, depending on the instructions.

All information about the product, including density, is applied to each package by stamping, applying a stencil paint or by printing on a label. Here you will find information about the manufacturer, the legend, date of manufacture and batch number, the amount of the substance in the package and the conformity mark.