The determination of bulk density indicates the amount of material in one cubic meter of bulk material. This value is determined as the number of voids between separate elements, and the size of the available fractions. You need to know the value of this indicator for correct calculations when creating solutions and purchasing materials. Units of measurement - kg/m3.

Determination of density

It is known that the composition of sand contains grains of medium, large and small fractions that affect the change in volume bulk material every time. Conditions according to which the indicator changes:

• degree of porosity;
• the structure of individual grains of sand;
• quantity and type of various impurities;
• humidity percentage indicator;
• sand moisture level.

The change in volume is most affected by the amount of moisture. The higher this indicator, the less construction sand density indicator, which significantly distinguishes a cube of dry material from a wet one in size.

Based on size, coarse-, medium- and fine-grained material is distinguished. How larger size grains of sand, the higher the bulk density. This is due to the presence of more significant voids. For smaller grains of sand in a unit volume, due to greater compaction, they are placed large quantity. Impurities are removed by washing the extracted sand, but this significantly increases its cost.

The porosity value indicates the nature and number of voids between individual grains. The higher this value, the lower the compaction rate. For loose sand this value is 47%, for compacted sand - 37%. Moisture reduces the number of voids as water fills them. The number of voids also decreases as a result of transportation, since due to the vibration that occurs during movement, the material sags. More compacted sand for construction purposes should be used when creating reinforced concrete and concrete products with maximum accuracy. They are able to withstand the heaviest loads with their even distribution.

What determines the degree of compaction?

The purpose of the material greatly depends on its density, for which types of buildings and types of structures its use is permissible. According to this indicator, the consumption of the amount required for certain purposes is calculated. After all, it is important to know the amount of mixture that will be obtained using a specific type starting materials. It is often necessary to convert mass to cubic meters and vice versa.

Some construction bases sell sand in tons, while others sell it in cubes.

To convert data to other units of the measuring system, you should use the school formula for volume and density:

P = m / V, Where:

• P - bulk density or degree of compaction;
• m is the calculated mass of bulk material;
• V is the available volume.

For example, let's calculate the density of an arbitrary type of sand weighing 3.2 tons or 3200 kg, occupying a volume of 2 m 3. The quantitative value of density according to the formula is found as:

P = 3200 / 2 = 1600 kg/m3.

Similarly, if you have data on the volume and a known degree of density of sand, you can find its wet weight or in its natural state of moisture:

The indicator is influenced by the following factors:

1. poured in the usual way sand has a significantly lower density than compacted during laying;
2. After caking the material at a certain stage, the sand varies in moisture content. Weight gain occurs as a result of water entering micropores between grains of sand;
3. The value of the bulk mass of bulk material is influenced by the presence of organic additives and soil-containing impurities. For most mortars According to the preparation technology, a fine filler of a high degree of purity is needed, which requires adjusting this indicator by sifting or washing;
4. Depending on the breed of origin, there are materials of different densities, which directly affect the weight;
5. The shapes, as well as the fractions of the existing grains, largely determine the density of the sand. The larger the fragments contained in the embankment, the greater the distance required between the grains filled with an air gap.

Density calculation

Different types of sand are delivered to the construction site. It can be used either immediately after delivery or after certain processing. When storing bulk material without cover outdoors, the density of sand grains constantly changes.

In practice, such calculations can be carried out independently. To do this, take a container of a certain volume. For example, this could be an 8 liter bucket. After pouring the materials into the bucket, use a ruler to level the surface of the heap. After weighing the filled bucket, as well as determining the mass of the container itself, the calculation formula takes the form:

P = (m 2 - m 1) / V, Where:

• m 1 is the weight of the container used to measure the density of the sample;
• m 2 is the total mass of the bucket filled with sand;
• V is the container volume, in our case 8 liters.

First you need to convert the volume into cubic meters, 8 liters is 0.008 m 3. In kilograms this is 0.45 kg, and a filled bucket of sand weighs 12.65 kg. The resulting density is defined as:

P = (12.65 - 0.45) /0.008 = 1525 kg/m3.

Using the compaction coefficient, without weighing the sand before use, you can determine its actual mass, which constantly changes for different types grain size of the material.

To obtain the desired result, you must multiply by the coefficient average density building materials. The table contains the coefficients of the most popular types of sand. However given value does not guarantee high accuracy, having an error of 5%. Weighing, which is inconvenient and sometimes not at all possible, is the single most reliable way to determine the density index. At the construction site, specialists can use any of the available methods.

When purchasing material, you should carefully calculate the moisture content of the purchased sand.

Density depending on the type of sand

Most often, quarry, river or building materials are used in construction. River sand is formed naturally because the rock is crushed naturally, which gives the sand grains a rounded shape. This material contains a minimum amount of impurities, which does not require additional processing. Depending on the size of the grains, several groups are distinguished:

• 2.9 - 5 - large;
• 2 - 2.8 - average;
• up to 2 - small.

The average bulk density is approximately 1650 kg/m3. This material has the main advantage of being environmentally friendly and safe.

The cost of this type of sand is very high, so according to technical standards it can easily be replaced by a career one.

This type of material contains various rocks - quartz, mica, spar. The name is assigned according to which element predominates in it. The main area of ​​application is the creation of bedding, foundation cushions, and gaskets. highways.

Properties of sand

There is also an indicator of the true degree of compaction. This value is determined exclusively in laboratory conditions. For this indicator, voids and gaps are not taken into account.

The grain size affects the amount of binder for a particular type of mortar. To make the structure strong, all voids must be closed with cement. This increases the cost of concrete or cement composition. IN quarry sand you need to pay attention to the degree of radioactivity. For the construction of residential buildings, it is necessary to use only quality class 1 material of this type.

Conclusion

The bulk density indicator is very important parameter sand, which affects the quality and strength of future structures. In addition, you need to know it for calculations building mixtures, the required amount of material. That is why this value cannot be ignored.

It is the ratio of the mass of this substance in a freshly poured 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 type of density is less than the true density, which excludes the above voids.

To determine bulk density, tools such as scales, a ruler, a “standard funnel” device, and a measuring vessel of a certain volume are used. Bulk density of a particular substance is determined for a material of a certain moisture content. If the sample does not meet the humidity standards, then it is moistened or, more often, dried.

When we determine what the bulk is, the algorithm of actions should be like this:

1. The measuring vessel is weighed and placed under a standard funnel (it has a shutter at the bottom).

2. Sand is poured into the funnel, after which the shutter is opened so that the sand is poured into the measuring vessel at once, fills it and forms a slide on top.

3. Excess sand is “cut off” with a ruler by moving it along the top of the measuring vessel.

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

5. 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 slightly compacted on a vibrating platform for 0.5-1 minutes. You can calculate the bulk volume using the same method.

In accordance with GOST 10832-2009, sand of a certain type (expanded) according to bulk density is divided into certain grades - from M75 (density indicator is 75 kg/m3) to M500 (density 400-500 kg/m3). To be classified as a particular brand, sand must have a certain thermal conductivity and compressive strength. For example, the thermal conductivity of grade M75 at a temperature of 25 C + -5C should be no more than 0.043 W/m x C. And the compressive strength for sand of grade M500 is defined as 0.6 MPa (not less). type (material moisture content 5%) has a bulk density of 1500. For cement, this figure is about 1200 kg/m3 in a free-fill state and about 1600 kg/m3 in a compacted state. Often, an average figure is used for calculations, which is equal to 1300 kg/cubic meter.

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

All product information, including density, is applied to each package by stamping, stenciling or printing on the label. Manufacturer information is provided here. symbols, date of manufacture and batch number, amount of substance in the package and

The average density of materials is understood as the ratio of the mass of a sample in a dry state to its volume. For materials that are pieces of various sizes (bulk materials), the concept of bulk density is used, which is the ratio of the mass of the material in bulk to its volume.

All the main properties of thermal insulation materials are related to their porosity, but the average (bulk) density has the most direct connection with porosity. Knowing this characteristic allows us to judge heat-shielding properties thermal insulation material. Based on the average density, thermal insulation materials are divided into grades: 15, 25, 35, 50, 75, 100, 125, 175, 200, 225, 250, 300, 350, 400, 450, 500, 600.

They consider a brand highest value average density within one of the above intervals. For example, a material with an average density of 310 kg/m3 is classified as grade 350, with an average density of 27 kg/m3 - as grade 35, etc.

All thermal insulation materials can be divided into three groups: hard(piece heat-insulating materials produced in the form of products of a certain specified shape), flexible(in the form of large-sized mats, mattresses, etc.) and loose(mineral and glass wool, expanded perlite and vermiculite, glass - pores).

Methods for determining average (bulk) density various types thermal insulation materials differ significantly from each other.

Determination of the average density of rigid thermal insulation materials carried out by measuring linear dimensions and weighing the products themselves or by measuring and weighing samples sawn, drilled or cut from various parts products. In this case, samples are usually pre-dried at a temperature of 105-110° S. Average Density (kg/m3)

Where M - sample mass or products, kg; V -sample volume or products, m3.

When determining the average density of a product in a naturally wet state, use the formula

Where Wa - absolute humidity material, by weight, %.

The dimensions of samples and products are found using a metal measuring tool (ruler, caliper). The length and width of products are measured in at least three places - at the edges and in the middle, A thickness in five to six places. For example, thickness fiberboard slabs measured at six points; on races standing 100mm from each the edges and in two places
Longitudinal center line of the slab. Thickness measurements can be made with a caliper or a special device - a thickness gauge (Fig. 7). The thickness gauge is used to measure the thickness of peat, hard mineral wool and thermal insulating fiberboards. The accuracy of measuring the thickness of the slabs when using a caliper and a thickness gauge is 0.1 mm, and when using a ruler it is 1 mm.

The average density of a batch of material is calculated as the arithmetic mean of at least three determinations. In this case, the weighing of hpo samples is carried out with an accuracy of 0.1 G, and products - up to 1 year

Determination of the average density of flexible thermal insulation materials proceed as follows. Three samples measuring 100 X 100 mm are cut from different places in each of the three felt panels selected for testing. The sample, weighed with an accuracy of 0.01 g, is placed on the base of a special device (Fig. 8). Plate 7 weighing 0.5 kg is brought close To record 6 and secure with a screw 5. Then the records 7 i 6 lowered down, without bringing the lower surface of plate 7 1-2 cm to the surface of the sample, and secure them with a screw 4. Having loosened screw 5, lower plate 7 onto the surface of the sample, leave it in this position for 5 minutes, after which, using arrow I, read on the scale 2 and determine the thickness of felt samples under a pressure of 0.0005 MPa. Movable plate 3 is also used for other tests of mineral wool products.

Average density of felt (kg/m3)

Рср_ 7(1 +0.01 W)"

The average density of a batch of felt will be characterized by the arithmetic average of nine determinations (nine samples from three products).

Average (bulk) density of loose thermal insulation materials fibrous structure depends on many factors. For example, the average density of mineral wool is influenced by the thickness of the fibers, the number of “kinglets” (vitreous spherical or pear-shaped inclusions larger than 0.25 mm that do not extend into the fibers), and the degree of compaction of the wool. To obtain comparable results, the average density fibrous materials determined under constant pressure. For example, average density mineral wool determined in special device(Fig. 9) under a pressure of 0.002 MPa. For this purpose, take five samples of cotton wool, 0.5 kg each. Weighing is carried out with an accuracy of 1 g. The cotton wool for each sample is taken as an average sample (0.5 kg of cotton wool is taken from five packages).

A sample of cotton wool is placed in layers in a metal cylinder 1. On top of the cotton wool using a lifting device 4 lower the metal one disk 2 mass 7 kg, which corresponds to the pressure on the cotton wool 0,002 MPa. Under The cotton wool is kept under load for 5 minutes And then determine the height of the layer of wool using a scale marked on rod 3. Calculate the volume of wool and, knowing it

The material is poured into the vessel from a height of 5 cm using a funnel or tray until a cone is formed. Excess material is removed with a metal ruler without compaction. The vessel, the mass of which is known, with the material is weighed with an accuracy of 1 g and the bulk density of the material is determined using a known formula.

The average density of pieces (grains) of loose thermal insulation material (for example, perlite crushed stone, expanded clay gravel etc.) are determined using sand volumeters or by immersion in measuring cylinders filled with water.

When using a sand volume meter (Fig. 10), the grain of the material being tested is placed inside the device. The grain volume will be equal to the difference between the sand levels in the device with and without the sample.

More accurately, the volume of a piece (grain) of material can be measured by immersing it in water, i.e., by the volume of water displaced by it. For this purpose, the sample, dried to a constant mass and pre-weighed to the nearest 0.1 g, is paraffinized (coated with a thin layer of molten paraffin) and then immersed in water located in a graduated cylinder. As a rule, the average density of pieces of porous materials is lower than the density of water, so full immersion sample is achieved using metal disk, the volume of which is known. The volume of the sample is calculated from the amount of water it displaces. In this case, the volume of the metal disk and paraffin is taken into account. Paraffin volume

Where m is the mass of paraffin applied to the sample, g; 0,93 - density of paraffin, g/cm3.

Knowing the volume. m of the sample and its mass, calculate the average density of this piece. To determine the average density “in a piece” of a batch of material, several dozen determinations are made and the arithmetic average is calculated.

Determination of the average density of flowable molding compounds (mortar mixtures, foam masses, slips) are carried out for control technological processes with certain thermal insulation materials. This, for example, is required in the manufacture of products from cellular, foam-ceramic or Lime-siliceous masses, etc.

The average density of mixtures in a liquid-fluid state is determined in a cylindrical vessel with a capacity of 1 liter. The vessel is filled with the test mixture, the excess mixture is cut off with a spatula or a metal ruler, and the vessel with the mass is weighed to the nearest 1 g. By subtracting the mass of the vessel from the total mass, the mass of the mixture is determined. The density of the mixture is calculated as the arithmetic mean of the results of two measurements.

If a mixture is tested With low mobility (up to 6 cm), then it is compacted on a vibrating table for 30 s Or on a shaking table, producing 120 strokes (shakes). In this case, a special nozzle is placed on top of the vessel, allowing the measuring vessel to be filled with some excess. After compaction, the nozzle is removed, and excess mixture is removed with a metal ruler.

Determination of the average density of mastic materials. The selected sample of the material is mixed with water to a normal (working) consistency, which is determined using a standard cone. The normal consistency of the solution corresponds to the immersion depth of the cone at 100+10 mm. Then the test mixture is placed in special molds, pre-cleaned and lubricated, measuring 200 X 50 X 25 mm, compacting it V corners of the mold with the tip of a knife and smoothing the surface flush with a knife or spatula With sides of the form.

Completed forms are placed V drying cabinet, where the samples are dried to a constant masses, then They are removed from the molds and sanded.

The resulting samples are measured with an accuracy of 0,1 mm, weighed to within 0.1 g and calculate the average density, kg/m3,

Construction Materials

Why do you need to know the density of construction sand (kg/m3)?

From the author: Hello, dear reader. From this article you will learn how the true density of construction sand kg/m3 is determined. Why is this necessary? - first of all, so as not to be deceived when purchasing this building material. Indeed, to determine exactly how many tons of sand for construction work they brought it to you - it’s quite difficult. You won't weigh the car, will you? And so, quite often suppliers of building materials take advantage of this, simply by not adding enough sand.

But knowledge of this criterion is important not only because of possible deception. The fact is that during construction, in principle, it is important to know what will be required, say, to pour a foundation or ceiling. After all, if suddenly there is not enough, it can turn into a real disaster, especially if the object must be delivered as soon as possible.

Let us begin, perhaps, with general definitions in order to properly introduce you to the matter. The bottom line is that the bulk density of construction sand is measured depending on how compacted the material is. The situation with cement is approximately the same: the older it is, the higher its density, since over time any bulk substance “crowds together.” An analogy can be drawn even with ordinary flour, which is used for baking.

It follows from this that the same volume of bulk substance can have different densities (and, therefore, - different quantities). In its original state (without compaction), the material can be characterized by the term “true bulk density”.

Therefore, bulk density is the density of the material in a state in which it has not been compacted. That is, - when determining this value - it is necessary to take into account not only the volume of grains of sand (or parts of other building materials), but also the distance at which they are removed from each other. From this we conclude that the bulk density is several times less than the usual density of the material.

After the material is compacted (and this depends primarily on the conditions in which it is stored and on time), its density ceases to be bulk. She's getting taller.

Why do you need to know what the density of sand (natural) is for construction work? First of all - to compare volume and mass building material. The price for bulk substances can be indicated not only for 1 t (ton), but also in cubic meters. And during preparation, the proportions of the substance may be needed not in weight, but in volume.

Below is a small table in which the second column shows the bulk density of construction sand (kg/m³), and the third column shows the number of cubes per 1 ton.

Important! With increasing density, the load-bearing capacity also increases.

What does density depend on?

The density of a bulk substance (in this case, sand) primarily depends on its origin and condition. The table below shows us the fundamental differences in bulk density of different types.

How to determine bulk density?

This indicator is usually determined in laboratory conditions. Essentially, the material is simply weighed using measuring vessels (1 l and 10 l). A liter container is used to determine the density in a state in which the material has not been compacted, the sand is dried to a constant mass and passed through a sieve with a hole diameter of 5 mm.

A ten-liter container is used when it is necessary to determine the indicator of the material that interests us, which is contained in the batch. In this way we can convert pass units into volume units.

In this case, the material is not specifically dried. It is taken in the state of moisture inherent natural state. It is also passed through a similar sieve (hole diameter 5 mm).

The procedure for determining density looks like this: the already sifted material is poured into a measuring vessel from a height of ±10 cm. For this, you should use a scoop. When the vessel is filled, the slide should be removed using a metal ruler. The height of the sand should be level with the edges of the measuring vessel. Next, this measuring vessel along with its contents should be weighed on precise scales. It goes without saying that we are only interested in the net weight of the contents, so the weight of the container should be subtracted.

To convert units of mass into units of volume, the procedure is essentially the same. As, indeed, the equipment. But you just need to pour the material not from 10 cm, but from 100 cm.

Below is the formula by which the indicator we are interested in is determined.

In this case, γn is an indicator of density, m1 is the mass of a measuring vessel without contents, m2 is the total mass, and V is, respectively, the volume.

To visually familiarize yourself with the determination procedure, watch the video below, where research is carried out in a virtual laboratory, under ideal conditions.

Conclusion

That's all, dear reader. Thank you for reading the article. Today we learned how to determine bulk density, and also found out why to do this. For convenience and clarity, we have provided a table and formula. I hope that the presented materials were useful to you.

If you are interested in another construction issue, - use the site navigation to find the information you need. I'm sure you'll find what you need here. Good luck and see you again at Seberemont, dear reader.

Bulk density - freely poured powder, depending on the granulometric composition and shape of the particles. The bulk density of the powder is determined by a device - a volume meter, by pouring the powder into a volumetric flask with a volume of 25 cm 3, followed by weighing and calculation using the formula: γ us = (M 2 -M 1)/V where M 1 - volumetric flask; M 2 - mass of a volumetric flask with powder; - measuring flask. The bulk density of the powder is taken into account when calculating the volume of the matrix cavity for pressing;
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encyclopedic Dictionary in metallurgy. - M.: Intermet Engineering. Chief Editor N.P. Lyakishev. 2000 .

See what “bulk density” is in other dictionaries:

bulk density- A certain mass of dry bulk material per unit volume, measured under conditions of a free, uncompacted state of dry bulk cargo. [GOST R 52202 2004 (ISO 830 99)] Topics cargo containers General terms containers for... ...

bulk density- 3.3 bulk density: Mass per unit volume of material with pores and voids. Source: GOST 10832 2009: Expanded perlite sand and crushed stone. Specifications original document... Dictionary-reference book of terms of normative and technical documentation

bulk density- piltinis tankis statusas T sritis Standartizacija ir metrologija apibrėžtis Laisvai supiltos birios medžiagos vienetinio tūrio masė. Matavimo vienetas: kg/m³. atitikmenys: engl. apparent density bulk density packed density vok. Schüttdichte, f… … Penkiakalbis aiškinamasis metrologijos terminų žodynas

bulk density- piltinis tankis statusas T sritis chemija apibrėžtis Laisvai supiltos birios medžiagos vienetinio tūrio masė (kg/m³). atitikmenys: engl. bulk density rus. bulk density … Chemijos terminų aiškinamasis žodynas

bulk density of coal- NDP. bulk mass coal The ratio of the mass of freshly poured coal to its volume, including the volume of pores and cracks inside grains and pieces, as well as the volume of voids between them, determined in established conditions filling the container. [GOST 17070 87]… … Technical Translator's Guide

bulk density of mineral fertilizer- The ratio of the mass of mineral fertilizer to its volume. Note The bulk density of mineral fertilizer can be with or without compaction. [GOST 20432 83] Fertilizer topics General terms quality mineral fertilizers … Technical Translator's Guide

bulk density of refractory raw material [unshaped refractory]- The ratio of the mass of refractory raw material [unmolded refractory] to its volume, expressed in grams per cubic centimeter. Note A distinction is made between the bulk density of loosely poured or tapped refractory raw materials [unshaped refractory]... Technical Translator's Guide

Bulk density of refractory raw materials- [unshaped refractory] - the ratio of the mass of refractory raw material [unshaped refractory] to its volume, expressed in grams per cubic centimeter. Note. A distinction is made between the bulk density of freely poured or after shaking... ... Encyclopedia of terms, definitions and explanations of building materials

bulk density of crushed wood- The ratio of the mass of chopped wood to its volume. [GOST 23246 78] Topics: crushed wood... Technical Translator's Guide

bulk density of mixture- - [A.S. Goldberg. English-Russian energy dictionary. 2006] Topics of energy in general EN mixture bulk density ... Technical Translator's Guide