The density of gravel - gravel, granite, limestone and slag. Bulk density of crushed stone: coefficient, GOST and definition

Crushed stone is a loose, inorganic and granular material obtained by artificial crushing. It is divided into primary and secondary. This is an important fact. Primary - the result of processing natural stone: pebbles, boulders, pumice and other materials. The secondary is obtained by crushing construction debris, such as concrete, asphalt, brick.

Method of obtaining

For the production of crushed stone, the following method is used: the rock, mined in the quarry, is crushed to a certain state by screening. During the recycling of the above construction waste, a mechanized crusher is used.

Application area

Due to its high adhesive properties, ie the ability to firmly adhere to the surface, crushed stone is used in cement-sand compositions, in town planning, in the construction of buildings, in the construction of roads and railways.

Material Features

The following are its main properties:

• Density of rubble.
• Flakiness (shape).
• Frost resistance.
• Strength.
• Radioactivity.

These values completely characterize this material. In more detail, we will consider such a property as the density of crushed stone. This is a significant definition.

Density of rubble

This property of the material is directly related to its strength. Density refers to the ratio of mass to volume. Measure it in tons or kilograms per cubic meter (t / m³, kg / m³). Distinguish the true density of rubble, without taking into account empty space, the general and bulk, i.e. in the unconsolidated state. Each of them has an appropriate meaning.

The true density of rubble is determined by the laboratory. That is, the mass of a unit volume of fine and dry material is measured. This method excludes the presence of voids filled with air. So determine the porosity.

The term "bulk density of crushed stone" is used to denote the relationship between mass and occupied volume, taking into account the free space between the particles. This parameter is necessary when calculating the composition of a concrete mixture.

Measurement of density

In this case, there are several ways to determine:

1. Using a measuring vessel.
2. Using tables.

We consider in more detail the first method

To perform this process, a measuring vessel of cylindrical shape with a volume of 5 to 50 liters is required to be completely filled up to form a cone at the top. Then the excess on top of the mold is removed. The vessel is weighed. To determine the density of crushed stone, calculate the difference between a full and empty vessel, which is divided by the volume of a given container. There is nothing complicated here. The formula in this case is as follows:

• Pn = (m ₂ - m ₁ ): V,

Where m ₁ is the mass of the empty vessel; M ₂ - with rubble, V - capacity of the measuring container.

Main criteria

To correctly measure the bulk density, comply with the requirements of the state standard, this is:

• Use only specialized vessels, that is, a certain shape and size.
• The size of the container is directly dependent on the grain size.
• Crushed stone is by no means especially compacted, since in this case the material will have other indicators.
• The total density is necessarily higher than the bulk density.

The results obtained in the laboratory are indicated in the accompanying passport of a particular lot.

In addition to rubble, the density of sand, concrete and other materials is likewise calculated. This takes into account the volume, graininess and space between the particles.

Definition using tables

This calculation of the density of these materials is also not unimportant. For large volumes or in cases where the error of about 1% is not critical, resort to the help of measuring tables with conditional coefficients for translation. Plus this method - saved time and simplicity. Less is an approximate, inaccurate result.

Tip

It should be remembered that bulk density is a quality natural, natural, excluding the possibility of subsequent tamping to eliminate voids.

For building materials, it is one of the basic parameters. On this depends the strength of the final product and the indirect determination of voids filled with a less strong composition of other elements.

In the manufacture of concrete mixtures, the rule is followed: the higher the fraction value, the lower the bulk density parameters. Knowing its performance can significantly save money. For example, with a low fraction and a high bulk density of cement, an order of magnitude less is required. With the knowledge of exact volumes, transportation and storage are simplified. It becomes possible to calculate the material for transportation. Also in this case, you can take into account the carrying capacity of transport.

Coefficient of density

Let's look at this definition. The technical value used during the measurements of the volume of crushed stone is called: the coefficient of bulk density of crushed stone. This is a significant parameter. Use its other name - the coefficient of compaction or translation (meaning the conversion of mass into volume, and vice versa).

Example

Let's say the car brought rubble to the construction site. How to make the necessary measurements? For this purpose, the volume of cargo and body along the filling margin is calculated. Then the values obtained are multiplied by the compaction factor. It is clear that the figures will be different due to the "tumbling" of the cargo during the movement, but it can not lose in mass. In the first case, taking into account the shrinkage, we can say that this is the total density of the rubble or a value close to it. In the second - bulk.

For a better understanding, let's take another life example. We bought some sugar. Let's say a kilogram. They fell asleep in the sugar bowl, received the primary volume. They shook, knocked, punched. Measured. The result is a finite volume.

Influencing factors

This is important to know. The density, from which the crushed stone is made, also influences the density. With the same volume - 1 m ³ , the weight of the granite will be 2.6 tons. However, limestone due to impurities of quartz, dolomites, etc. - 2.7-2.9 tons. With the same weight, the volume will vary.

As a result, large, unmilled rock takes up less space than recycled. This is due to the space between the elements. The difference in volume with the same mass will be spoken by the true and bulk of the rubble. This is a reliable fact. So, for example, the true density of granite rubble with a fraction (grain size) from 5 to 20 mm is 2590 kg / m ³ , and the bulk of the same material will be equal to 1320 kg / m³. Thus, knowing this definition, you can significantly save on reducing costs in the process of shutting down concrete mix, as well as on transportation means and storage areas.

Other options

In this case, we can distinguish the following:

• Fraction is the grain size of the material. There are standard (5-10 mm, 10-20, 5-20 , etc.), non-standard (10-15 mm, more than 15 to 20 mm, etc.) and Euro-slab (3-5 mm).
• Mark of crushed stone for durability. There are several types. Namely: the usual strength of M 800-1200; High - M 1400-1600; Average - M 600-800; Weak - M 300-600; The minimum is M 200.

The totality of the fraction, mark and source rock will affect the bulk density.