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

2024 Author: Howard Calhoun | [email protected]. Last modified: 2024-01-17 18:37

Crushed stone is a free-flowing, 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. Secondary is obtained by crushing construction waste, such as concrete, asph alt, brick.

Delivery method

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

Scope of application

Due to the high adhesive properties, i.e. the ability to firmlyto adhere to the surface, crushed stone is used in cement-sand compositions, in urban planning, in the construction of buildings, in the construction of roads and railways.

Material features

The following main properties are distinguished:

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

These values fully characterize the specified material. Next, we consider in more detail such a property as the density of crushed stone. This is a not insignificant definition.

Crushed stone density

This property of the material is directly related to its strength. Density is the ratio of mass to volume. It is measured in tons or kilograms per cubic meter (t / m³, kg / m³). Distinguish the true density of crushed stone, without taking into account empty space, total and bulk, i.e., in an uncompacted state. Each of them has a corresponding meaning.

The true density of crushed stone is determined by the laboratory. That is, the mass per unit volume of fine and dry material is measured. This method excludes the presence of voids filled with air. This is how porosity is determined.

The term "bulk density of crushed stone" is used to denote the ratio between the mass and the occupied volume, taking into account the freespaces between particles. This parameter is required when calculating the composition of the concrete mix.

Density measurement

In this case, there are several ways to determine:

1. With a measuring vessel.
2. With the use of tables.

Let's take a closer look at the first method

To carry out this process, it is necessary to completely fill a cylindrical measuring vessel with a volume of 5 to 50 liters until a cone forms at the top. Then the excess on top of the form 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 this container. There is nothing complicated here. The formula in this case looks like this:

• Рн=(m₂ – m_{1): V,}

where m₁ is the mass of the empty vessel; m_{2 - with crushed stone, V - capacity of measuring tank.}

Main criteria

To correctly measure the bulk density, comply with the requirements of the state standard, these are:

• Using only specialized vessels, that is, of a certain shape and size.
• The size of the container directly depends on the grain size.
• Crushed stone is in no case specially compacted, since in this case the material will have different indicators.
• Total density is necessarily higher than bulk density.

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

In addition to crushed stone, the density of sand, concrete and other materials is calculated in a similar way. This takes into account the volume, granularity and space between the particles.

Determination using tables

This calculation of the density of these materials is also important. For large volumes or in cases where an error of about 1% is not critical, resort to measuring tables with conditional conversion factors. The advantage of this method is time saving and simplicity. Minus - approximate, inaccurate result.

Table: "Bulk density of crushed stone (GOST 9758)"

Type of rubble	Faction, mm	Bulk density, kg/m³	Brand
Granite	20-40	1370-1400	M 1100
	40-70	1380-1400	M 1100
	70-250	1400	M 1100
Limestone	10-20	1250	M 1100
	20-40	1280	M 1100
	40-70	1330	M 1100
Gravel	0-5	1600	M 1100
	5-20	1430	M 1100
	40-100	1650	M 1100
	more than 160	1730	M 1100
Slag		800	M 800
Expanded clay	20-40	210-340	M 200, M 300
	10-20	220-440	M 200, M 300, M 350, M 400
	5-10	270-450	M 250, M 300, M 350, M 450
Secondary		1200-3000	M 1100

Tip

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

In building materials, it is one of the basic parameters. The strength of the final product and the indirect determination of voids filled with a less durable composition of other elements depend on this.

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

Density factor

Let's deal with this definition. The technical value used during measurements by volume of crushed stone is called as follows: the coefficient of bulk density of crushed stone. It's not significantparameter. Its other name is also used - the coefficient of compaction or conversion (meaning the conversion of mass into volume, and vice versa).

Example

Let's say a car brought crushed stone to a construction site. How to take the necessary measurements? To do this, the volume of cargo and body along the filling boundary is calculated. The obtained values are then multiplied by the compaction factor. It is clear that the figures will be different due to the "shaking" of the cargo during movement, but it cannot lose weight. In the first case, taking into account shrinkage, we can say that this is the total density of crushed stone or a value close to it. In the second - bulk.

For a better understanding, let's take another life example. Bought some sugar. Let's say a kilogram. They fell asleep in a sugar bowl, got the primary volume. They shook, they knocked, they rammed. Measured. We got the final volume as a result.

Influencing factors

This is important to know. The density is also influenced by the rock from which the crushed stone is made. With the same volume - 1 m3, the weight of granite will be 2.6 tons. However, limestone due to impurities of quartz, dolomites, etc. - 2.7-2.9 tons. the same weight will be different volume.

As a result, large, uncomminuted rock takes up less space than recycled rock. This is due to the space between the elements. The true and bulk area of crushed stone will speak about the difference in volumes with the same mass. This is a true fact. So, for example, the true density of crushed granite with a fraction (grain size) from 5 to 20 mm will be 2590 kg/m3, and bulkthe same material will be equal to 1320 kg / m³. Thus, knowing this definition, you can significantly save on reducing costs in mixing concrete, as well as on means of transportation and storage.

Other options

In this case, the following can be distinguished:

• Fraction - the grain size of the material. There are standard (5-10 mm, 10-20, 5-20, etc.), non-standard (10-15 mm, over 15 to 20 mm, etc.) and Euro-crushed stone (3-5 mm).
• Brand of crushed stone for strength. There are several types. Namely: normal strength M 800–1200; high - M 1400-1600; medium - M 600-800; weak - M 300-600; minimum - M 200.

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