What is the compaction ratio of bulk solids? Sand gravel compaction coefficient. Crushed stone compaction coefficient - what is it? Opps seal safety factor

The compaction coefficient of any bulk material shows how much its volume can be reduced with the same mass by ramming or natural shrinkage... This indicator is used to determine the amount of aggregate both during purchase and during the construction process itself. Since the bulk weight of crushed stone of any fraction after compaction will increase, it is necessary to immediately lay a stock of material. And in order not to buy too much, a correction factor will come in handy.

Compaction factor (К у) - important indicator, which is needed not only for the correct formation of the order of materials. Knowing this parameter for the selected fraction, it is possible to predict further shrinkage of the gravel layer after loading it building structures as well as the stability of the objects themselves.

Since the ramming ratio is the rate of volume reduction, it changes under the influence of several factors:

1. The method and parameters of loading (for example, from what height the filling is performed).

2. The peculiarities of transport and the duration of the journey - after all, even in a stationary mass, a gradual compaction occurs when it sags under its own weight.

3. Fractions of crushed stone and grain content smaller than the lower limit of a particular class.

4. Flakiness - needle stones do not settle as much as cuboid stones.

The strength depends on how accurately the degree of compaction was determined. concrete structures, foundations of buildings and road surfaces.

However, do not forget that the ramming on the site is sometimes performed only on the upper layer, and in this case the calculated coefficient does not fully correspond to the actual shrinkage of the pillow. This is especially true for home craftsmen and semi-professional construction crews from the near abroad. Although, according to the technology requirements, each layer of backfill must be rolled and checked separately.

Another nuance - the degree of ramming is calculated for a mass that is compressed without lateral expansion, that is, it is limited by walls and cannot creep. At the site, such conditions for filling any fraction of crushed stone are not always created, so that a small error will remain. Take this into account when calculating the settlement of large structures.

Sealing during transportation

Finding some standard value of compressibility is not so easy - too many factors affect it, as we talked about above. The crushed stone compaction factor can be indicated by the supplier in the accompanying documents, although GOST 8267-93 does not directly require this. But transporting gravel, especially in large batches, reveals a significant difference in volume at loading and at the final point of delivery of the material. Therefore, the correction factor, taking into account its compaction, must be entered into the contract and monitored at the reception point.

The only mention from the outside current GOST- the declared indicator, regardless of the fraction, should not exceed 1.1. Suppliers, of course, are aware of this and try to keep a small stock so that there are no returns.

The measurement method is often used during acceptance, when crushed stone is brought to the site for construction, because it is ordered not in tons, but in cubic meters. With the arrival of transport, the loaded body must be measured from the inside with a tape measure in order to calculate the volume of gravel delivered, and then multiply it by a factor of 1.1. This will allow you to roughly determine how many cubes were poured into the machine prior to shipment. If the figure obtained taking into account the seal is less than that indicated in the accompanying documents, then the car was underloaded. Equal or more - you can command unloading.

Sealing on site

The above figure is taken into account only for transportation. In the conditions of a construction site, where the compaction of crushed stone is carried out artificially and using heavy machines (vibrating plate, roller), this coefficient can increase to 1.52. And performers need to know the shrinkage of the gravel backfill for sure.

Usually the required parameter is set in project documentation... But when exact value it is not necessary, use the averaged indicators from SNiP 3.06.03-85:

For strong crushed stone of fraction 40-70, a compaction of 1.25-1.3 is given (if its grade is not lower than M800).
For rocks with a strength up to M600 - from 1.3 to 1.5.

For small and medium size classes 5-20 and 20-40 mm, these indicators have not been established, since they are more often used only when the upper bearing layer is split from 40-70 grains.

Laboratory research

The compaction ratio is calculated based on laboratory test data, where the mass is compacted and checked for various devices... There are methods here:

1. Substitution of volumes (GOST 28514-90).

2. Standard layer-by-layer compaction of crushed stone (GOST 22733-2002).

3. Express methods using one of three types of densitometers: static, water-balloon or dynamic.

Results can be obtained immediately or after 1-4 days, depending on the selected study. One sample for standard test will cost 2500 rubles, in total they will need at least five. If data is needed during the day, express methods are used based on the selection of at least 10 points (850 rubles for each). Plus, you will have to pay for the visit of the laboratory assistant - about 3 thousand more. But in the construction of large facilities, one cannot do without accurate data, and even more so without official documents confirming the contractor's compliance with the project requirements.

How to find out the degree of ramming yourself?

V field conditions and for the needs of private construction, it will also be possible to determine the desired coefficient for each size: 5-20, 20-40, 40-70. But for this, you first need to know their bulk density. It varies depending on the mineralogical composition, albeit insignificantly. The crushed stone fractions have a much greater influence on the bulk density. For the calculation, you can use the averaged data:

Fractions, mm	Bulk density, kg / m3
Fractions, mm	Granite	Gravel
0-5	1500	—
5-10	1430	1410
5-20	1400	1390
20-40	1380	1370
40-70	1350	1340

More accurate density data for a specific fraction is determined in a laboratory way. Or weighing a known volume construction rubble followed by a simple calculation:

Bulk density = weight / volume.

After that, the mixture is rolled up to the state in which it will be used on the site and measured with a tape measure. The calculation is performed again using the above formula, and as a result, two different densities are obtained - before and after tamping. Dividing both numbers, we find out the compaction coefficient specifically for this material. With the same sample weight, you can simply find the ratio of the two volumes - the result will be the same.

Please note: if the indicator after tamping is divided by the original density, the answer will be more than one - in fact, this is the safety factor of the material for compaction. In construction, it is used if the final parameters of the gravel pad are known and it is necessary to determine how much crushed stone of the selected fraction to order. The reverse calculation results in a value less than one. But these figures are equivalent and when calculating it is important only not to get confused which one to take.

Sand (K upl) is known not only by specialists working in design organizations, but also operators, whose main activity is construction. It is calculated in order to compare the actual density in a certain area, with the value prescribed by regulatory enactments. The compaction ratio of bulk materials is important criterion, by which the quality of preparation for the main types of work on construction sites is assessed.

What it is?

K opl characterizes the density that the soil has in a specific area, refers to the same indicator of the material that has undergone standard compaction in the laboratory. It is this figure that is used to assess the quality of the work performed. This coefficient determines how the soil on the site meets the requirements of GOST 8736-93 and 25100-95.

At various works sand can have different indicator density. All these norms are spelled out in SNiP 2.05.02-85, table 22. They are also usually indicated in project documents, in most cases this indicator ranges from 0.95 to 0.98.

What changes the density coefficient

If you do not understand what sand ramming is, then it is practically impossible to calculate the correct amount of material during construction. After all, you need to clearly know how various manipulations have affected the soil. What ratio of the relative compaction of sand we get in the end can depend on many factors:

from the method of transportation;
how long the route was;
whether there is any damage of a mechanical nature;
presence of extraneous inclusions;
moisture ingress.

Naturally, if you ordered sand, then you simply have to check it on the spot, because late claims will be completely inappropriate.

Why Consider Relative Factor When Building Roads

This indicator for a sand cushion must be calculated, and this is due to an ordinary physical phenomenon that is familiar to any person. To understand this, remember how the loosened soil behaves. At first, it is loose and voluminous. But after a couple of days it will settle and become much denser.

The same fate awaits any other bulk material. After all, its density increases in the warehouse under the pressure of its own weight. Then, during loading, it is loosened, and already directly on the construction site, the sand is again tamped with its own weight. In addition, moisture affects the soil. The sand cushion will be compacted in any type of work, whether it is road construction or backfilling of the foundation. For all these factors, the corresponding GOST (8736-93 and 25100-95) were calculated.

How to use a relative indicator

For any construction works ah, one of the most important stages is the preparation of estimates and calculation of coefficients. This is necessary in order to correctly draw up a project. If it is important to find out how much the sand will be compacted during transportation in a dump truck or railway carriage, it is enough to find the required indicator in GOST 8735-88 and divide the required volume by it.

It is also necessary to take into account what kind of work lies ahead. Either you are going to make a sand cushion under the roadway, or backfill the foundation. In each situation, the ramming will proceed differently.

For example, when sand is backfilled, a dug pit is filled. Tamping is done using various equipment. Sometimes compaction is done with a vibrating plate, but in some cases a roller is required. Accordingly, the indicators will be different. Keep in mind that the soil changes its properties during excavation. So the amount of backfill must be considered taking into account the relative indicator.

The table of values of the compaction coefficients depending on the purpose of the sand.

What is the compaction ratio of bulk solids? Sand gravel compaction coefficient

Compaction coefficient of sand and gravel mixture

All building materials, especially mixtures, have a number of indicators, the value of which plays an important role in the process of construction work and largely determines the final result. For bulk materials, such indicators are the size of the fraction and the compaction coefficient. This indicator records how much the outer volume of the material decreases when it is compacted (compacted). This coefficient is most often taken into account when working with construction sand, however, both sand and gravel mixtures and just gravel itself can also change their value during compaction.

Why do you need to know the compaction coefficient of a sand and gravel mixture?

Any free-flowing mixture, even in the absence of mechanical stress, changes its density. This is easy to understand if you remember how a mountain of sand that has just been dug changes over time. The sand becomes denser, then, with repeated processing, it returns again to a more free-flowing, changing the volume of the occupied area. How much this volume increases or decreases is the density coefficient.

This coefficient of compaction of a sand and gravel mixture does not record the volume lost during artificial compaction (for example, during the construction of a substrate for a foundation, when the mixture is rammed with a special mechanism), but natural changes that occur with the material during transportation, loading and unloading. This allows you to determine the losses received during transportation and more accurately calculate the required volume of supply of sand and gravel mixture. It should be noted that the size of the compaction coefficient of the sand-gravel mixture is influenced by many indicators, such as the size of the batch, the method of transportation, the initial quality of the sand itself.

In construction work, information on the compaction volume is used in calculations and preparation for construction. In particular, based on this parameter, certain indicators are established for the depth of the trench, the thickness of the backfill for future pillow from a sand and gravel mixture, the intensity of ramming and much more. Among other things, the season is taken into account, as well as climatic indicators.

The size of the compaction coefficient of the sand and gravel mixture may vary for different materials, each type of free-flowing mixture has its own standard indicators that guarantee its quality. It is believed that the average size of the compaction coefficient for a sand and gravel mixture is about 1.2 (these data are indicated in the GOST). It should be borne in mind that the same indicator, but separately for sand and gravel, will be different, from 1.1 to 1.4, depending on the type and size of fractions.

When performing construction work, purchase materials with the required coefficient, otherwise, the quality of construction may suffer.

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vyborgstroy.com

Compaction factors of bulk materials for construction

The essence of determining the compaction coefficient of gravel, sand, crushed stone and expanded clay can be briefly described as follows. This is a value equal to the ratio of the density of bulk building material to its maximum density.

This coefficient is different for all bulk solids. For ease of use, its average value is enshrined in regulatory enactments, the observance of which is mandatory for all construction work. Therefore, if it is required, for example, to find out what the coefficient of compaction of sand is, it will be enough just to look in GOST and find the required value. Important note: all values given in regulatory enactments are average and may vary depending on the conditions of transportation and storage of the material.

The need to take into account the compaction factor is due to a simple physical phenomenon familiar to almost all of us. In order to understand the essence of this phenomenon, it is enough to remember how the excavated earth behaves. At first, it is loose and quite voluminous. But if you look at this land in a few days, it will already become noticeable that the soil has "settled" and compacted.

The same thing happens with building materials. First, they lie with the supplier in a state compacted by their own weight, then during loading, they are "loosened" and increase in volume, and then, after unloading at the facility, natural compaction with their own weight occurs again. In addition to mass, the material will be affected by the atmosphere, or rather, its moisture. All these factors are taken into account in the corresponding GOSTs.

Crushed stone delivered by road or rail is weighed on a scale. On delivery aquatic species transport weight is calculated based on the draft of the vessel.

How to use the odds correctly

An important stage of any construction work, it becomes the compilation of all estimates with the obligatory consideration of the compaction coefficients of bulk materials. This must be done in order to include in the project the correct and necessary amount of building materials and to avoid their overabundance or shortage.

How to use the odds correctly? It couldn't be easier. For example, in order to find out how much material will be obtained after shaking in the body of a dump truck or in a wagon, it is necessary to find in the table the required coefficient of compaction of soil, sand or crushed stone and divide the purchased volume of products by it. And if you need to know the volume of materials before transportation, then you will need to do not division, but multiplication by the appropriate coefficient. For example, if 40 cubic meters of crushed stone was purchased from a supplier, then, in the process of transportation, this amount will turn into the following: 40 / 1.15 = 34.4 cubic meters.

Work related to the complete chain of sand mass movement from the bottom of the open pit to the construction site should be carried out taking into account the relative reserve factor of sand and soil for compaction. It is a value that shows the ratio of the weight density of the solid structure of the sand to its weight density at the supplier's shipping area. To determine the required amount of sand, providing the planned volume, you need to multiply this volume by the coefficient of relative compaction.

In addition to knowing the relative coefficient given in the table, correct use GOST implies the mandatory consideration of the following factors for the delivery of sand to construction site:

physical properties and chemical composition of the material inherent in a particular area;
conditions of carriage;
taking into account climatic factors during the delivery period;
obtaining in laboratory conditions the values of the maximum density and optimum humidity.

Compaction of sandy substrates

This view work is necessary when backfilling. For example, this is necessary after the foundation has been installed and now it is required to fill the gap formed between the outer contour of the structure and the walls of the pit with soil or sand. The process is carried out using special ramming devices. The compaction coefficient of the sandy base is approximately 0.98.

Coefficient for concrete mixes

Concrete mix, like any other building material, mounted by filling or pouring, requires further compaction to obtain the required density, and hence the reliability of the structure. The concrete is compacted with vibrators. In this case, the coefficient of compaction of the concrete mixture is taken in the range from 0.98 to 1.

taxi-pesok.ru

Coefficient for compaction and loss of SGM

Carrying out the construction of energy complex facilities and being guided by design data, the construction of embankments, backfilling of trenches, pits, sinuses of excavations, bedding under the floors must be done with imported soil (sand, crushed stone, ASG, etc.) with a compaction coefficient of up to 0.95.

When compiling local estimates for these types of work, we use the prices: EP 01-01-034 "Backfilling of trenches and pits with bulldozers", EP 01-02-005 "Compaction of soil with pneumatic rammers" - when backfilling with a bulldozer and EP 01-02-061 " Backfilling of trenches, pits and pits by hand "- when backfilling manually.

Since backfilling is carried out with imported soil (sand, crushed stone, ASG, etc.), in addition to the prices, we take into account its cost. Since the prices take into account the soil in a dense body, we, when calculating the volume of imported soil required for the production of work and imported to the construction site in a loosened state, apply a compaction coefficient of 1.18 in accordance with clause 2.1.13 of the Technical part of the Collection of GESN-2001- 01 (revised 2008-2009).

In addition, when backfilling trenches and sinuses of excavations with a bulldozer, we take into account the losses of ASM in accordance with clause 1.1.9 of the Technical part of the GESN-2001-01 Collection (revised 2008-2009):

in the amount of 1.5% - when moving the soil with a bulldozer on the base, folded with soil of a different type,
in the amount of 1% - when transporting by road over a distance of more than 1 km.

I ask you to confirm the legality of our actions, since the Customer requires the coefficient for compaction (1.18) and the loss of SGM (1.5% and 1%) should be excluded from the estimates.

The provisions of clause 2.1.13 of Section II "Calculation of the scope of work" of the state estimated standards HPES (FER) - 2001, approved by order of the Ministry of Regional Development of Russia dated November 17, 2008 No. 253 (hereinafter referred to as the Standards), are applicable in determining the estimated cost of work but filling the embankments of iron and highways.

Based on the data presented in the circulation on the backfilling of trenches, pits and pits, the use of a compaction factor of 1.18, specified in clause 2.1.13 of the Standards, seems unreasonable.

In accordance with paragraph 1.1.9 of Section I "General Provisions" of the Standards, the volume of soil to be transported by road to the facility for backfilling of trenches and pits, when transporting by road over a distance of more than 1 km - 1.0%; when the soil is moved by bulldozers on the base, folded with soil of a different type, it is calculated according to the design dimensions of the embankment with an addition of 1.5% for losses.

In accordance with clause 7.30 of the set of rules "SP 45.13330.2012. Set of rules. Earth structures, foundations and foundations. Updated edition of SNiP 3.02.01-87",

approved by order of the Ministry of Regional Development of Russia dated December 29, 2011 No. 635/2, it is allowed to accept a larger percentage of losses with sufficient justification, by the joint decision of the customer and the contractor.

smetnoedelo.ru

snip table, when tamping, when backfilling and GOST 7394 85

The compaction coefficient must be determined and taken into account not only in narrowly focused areas of construction. Professionals and ordinary workers performing standard sand handling procedures are constantly faced with the need to determine the coefficient.

The compaction coefficient is actively used to determine the volume of bulk materials, in particular sand, but also applies to gravel and soil. The most accurate method for determining compaction is the gravimetric method.

Wide practical use not found due to the inaccessibility of equipment for weighing large volumes of material or the lack of sufficiently accurate indicators. Alternative option coefficient output - volumetric accounting.

Its only drawback is the need to determine the compaction at different stages. This is how the coefficient is calculated immediately after extraction, during storage, during transportation (relevant for road transport) and directly at the end user.

Factors and properties

The compaction coefficient is the dependence of the density, that is, the mass of a certain volume, of the controlled sample to the reference standard.

Density reference values are derived under laboratory conditions. The characteristic is necessary for carrying out assessment work on the quality of the completed order and compliance with the requirements.

To determine the quality of the material, regulatory documents are used in which reference values are prescribed. Most of the prescriptions can be found in GOST 8736-93, GOST 7394-85 and 25100-95 and SNiP 2.05.02-85. It can additionally be discussed in the project documentation.

In most cases, the compaction ratio is 0.95-0.98 of the standard value.

"Skeleton" is a solid structure that has some parameters of looseness and moisture. Volume weight usually calculated based on the interdependence of the mass of solid particles in the sand, and that which the mixture would acquire if the water occupied the entire space of the soil.

The best way to determine the density of quarry, river, building sand is to conduct laboratory studies based on several samples taken from the sand. During the survey, the soil is gradually compacted and moisture is added, this continues until the normalized moisture level is reached.

After reaching the maximum density, the coefficient is determined.

Relative compaction ratio

Carrying out numerous procedures for extraction, transportation, storage, it is obvious that the bulk density changes somewhat. This is due to the compaction of sand during transportation, a long stay in the warehouse, moisture absorption, a change in the level of looseness of the material, the size of the grains.

In most cases, it is easier to get by with the relative coefficient - this is the ratio between the density of the "skeleton" after extraction or being in a warehouse to that which it acquires when it reaches the end consumer.

Knowing the rate of what the density is characterized during extraction is indicated by the manufacturer, it is possible to determine the final coefficient of the soil without carrying out constant surveys.

Information about this parameter should be indicated in the technical, project documentation. Determined by calculations and the ratio of the initial and final indicators.

This method assumes regular supplies from one manufacturer and no change in any variables. That is, transportation is carried out by the same method, the quarry has not changed its qualitative indicators, the duration of stay in the warehouse is approximately the same, etc.

To perform calculations, it is necessary to take into account the following parameters:

characteristics of sand, the main ones are the compressive strength of the particles, grain size, caking;
determination of the maximum density of the material in laboratory conditions with the addition of the required amount of moisture;
bulk density of the material, that is, the density in its natural environment;
type and conditions of transportation. The strongest shaking of the car and railway transport... Sand is less compacted during sea shipping;
weather conditions during the transportation of soil. It is necessary to take into account humidity and the likelihood of exposure from the outside sub-zero temperatures.

During mining

Depending on the type of excavation, the level of sand extraction, its density also changes. In this case, an important role is played by climatic zone, in which work is carried out to extract the resource. The documents determine the following coefficients depending on the layer and region of sand extraction.

In the future, on this basis, you can calculate the density, but you need to take into account all the effects on the soil, which change its density in one direction or the other.

When tamping and backfilling

Backfilling is the process of filling a pit, previously dug, after erection necessary buildings or carrying out certain works. Usually covered with soil, but quartz sand also used frequently.

The ramming is considered necessary process with this action, since it allows the strength to be restored to the coating.

To perform the procedure, you must have special equipment. Commonly used shock mechanisms or those that create pressure.

Vibration stamp and vibration plate are actively used in construction. of various weights and power.

The compaction ratio also depends on the rammer and is expressed as a proportion. This must be taken into account, since an increase in compaction simultaneously decreases the volumetric area of the sand.

It should be borne in mind that all types of mechanical, outer seal are capable of acting only on the top layer of the material.

The main types and methods of compaction and their effect on the upper layers of the soil are presented in the table.

To determine the volume of backfill material, it is necessary to take into account the relative compaction factor. This is due to the change physical properties pit after pulling out the sand.

When pouring the foundation, you need to know correct proportions sand and cement. By clicking on the link, see the proportions of cement and sand for the foundation.

Cement is a special bulk material, which in its composition is a mineral powder. Here are the different brands of cement and their application.

With the help of plaster, the thickness of the walls is increased, which increases their strength. Here you will find out how long the plaster dries.

When extracting the quarry sand, the body of the quarry becomes looser and the density may decrease in stages. Periodic laboratory-assisted density checks should be performed, especially when the composition or location of the sand changes.

For more information on compaction of sand during backfilling, see the video:

During transportation

The transportation of bulk materials has some peculiarities, since the weight is quite large and there is a change in the density of resources.

Basically, sand is transported by road and rail transport, and they cause shaking of the load.

Transportation by car

Constant vibration shocks to materials act on it like a compaction from a vibrating plate. So the constant shaking of the load, the possible impact of rain, snow or freezing temperatures, increased pressure on the lower layer of sand - all this leads to the compaction of the material.

Moreover, the length of the delivery route is in direct proportion to compaction until the sand reaches the maximum possible density.

Sea shipping is less susceptible to vibration, so the sand retains a greater level of looseness, but some, slight shrinkage is still observed.

To calculate the quantity building material you need a relative compaction coefficient, which is displayed individually and depends on the density at the start and end points, multiplied by the required volume introduced into the project.

In laboratory conditions

It is necessary to take sand from the analytical stock, about 30 g. Sift through a sieve with a grid of 5 mm and dry the material until a constant weight value is obtained. Bring the sand to room temperature. Dry sand should be mixed and divided into 2 equal parts.

Next, you need to weigh the pycnometer and fill 2 samples with sand. Then, in the same amount, add distilled water to a separate pycnometer, approximately 2/3 of the total volume and weigh again. The contents are mixed and placed in a sandy bath with a slight slope.

To remove air, it is necessary to boil the contents for 15-20 minutes. Now you need to cool the pycnometer to room temperature and wipe it off. Then add up to the mark with distilled water and weigh.

P = ((m - m1) * Pв) / m-m1 + m2-m3, where:

m is the mass of the pycnometer when filled with sand, g;
m1 is the weight of the empty pycnometer, g;
m2 - mass with distilled water, g;
m3 is the weight of the pycnometer with the addition of distilled water and sand, and after getting rid of air bubbles
Pw - water density

In this case, several measurements are carried out, based on the number of samples provided for verification. Results should not deviate more than 0.02 g / cm3. In case of a large consumption of the received data, an average arithmetic number.

Estimation and calculations of materials, their coefficients are the main component of the construction of any objects, as it helps to understand the amount of material required, and therefore costs.

For correct drafting estimates it is necessary to know the density of the sand, for this, the information provided by the manufacturer, based on surveys and the relative coefficient of compaction upon delivery, is used.

What causes the compaction level to change

The sand passes through a rammer, not necessarily a special one, possibly in the process of moving. It is quite difficult to calculate the amount of material obtained at the output, taking into account all the variables. For an accurate calculation, you need to know all the impacts and manipulations carried out with the sand.

The final compaction ratio depends on a variety of factors:

method of transportation, the more mechanical contact with irregularities, the stronger the seal;
duration of the route, information is available to the consumer;
the presence of damage from mechanical influences;
the amount of impurities. In any case, foreign components in the sand give it more or less weight. The cleaner the sand, the closer the density value is to the reference;
the amount of moisture that has entered.

Immediately after purchasing a batch of sand, it should be checked.

Samples need to be taken:

for a batch of less than 350 tons - 10 samples;
for a batch of 350-700 tons - 10-15 samples;
when ordering more than 700 tons - 20 samples.

The samples obtained should be taken to a research institution for conducting surveys and comparing the quality with regulatory documents.

Conclusion

The required density strongly depends on the type of work. Basically, compaction is needed to form the foundation, backfill trenches, create a cushion for the roadway, etc. The quality of the compaction must be taken into account, each type of work has different requirements for compaction.

In the construction of highways, a roller is often used; in places that are difficult to access for transport, a vibrating plate of various capacities is used.

So to determine the final amount of material, it is necessary to lay the compaction coefficient on the surface during compaction, this ratio is indicated by the manufacturer of the compaction equipment.

The relative indicator of the density coefficient is always taken into account, since soil and sand tend to change their indicators based on the level of moisture, the type of sand, fraction and other indicators.

strmaterials.com

Crushed stone compaction ratio: gravel, granite and dolomite

The compaction coefficient of crushed stone is a dimensionless indicator characterizing the degree of change in the volume of material during compaction, shrinkage and transportation. It is taken into account when calculating the required amount of filler, checking the mass of products delivered to order and when preparing the bases for bearing structures along with bulk density and other characteristics. The regulatory number for a specific brand is determined in laboratory conditions, the real one is not a static value and the same depends on a number of inherent properties and external conditions.

Determination of the coefficient
Ramming during transport and on site
Bulk density for different fractions

Functional value of the indicator

The compaction ratio is used when working with bulk building materials. Their normative number varies from 1.05 to 1.52. average value for gravel and granite crushed stone is 1.1, expanded clay - 1.15, sand and gravel mixtures- 1.2 (read about the degree of compaction of sand here). The actual figure depends on the following factors:

Sizes: the smaller the grain, the more efficient the ramming is.
Flakiness: acicular and irregularly shaped crushed stone is compacted worse than cuboid fillers.
The duration of transportation and the type of transport used. The maximum value is achieved when delivering gravel and granite stone in dump trucks and railway wagons, the minimum - in sea containers.
Car backfill conditions.
Method: it is more difficult to achieve the desired parameter with manual operation than when using vibration equipment.

In the construction industry, the compaction factor is taken into account primarily when checking the mass of the purchased bulk material and backfilling the foundations. The design data indicates the density of the skeleton of the structure. The indicator is taken into account in combination with other parameters of building mixtures, humidity plays an important role. The degree of tamping is calculated for crushed stone with a limited volume of walls; in reality, such conditions are not always created. A striking example the backfilled foundation or drainage cushion serves (fractions go beyond the interlayer), an error in the calculation is inevitable. To neutralize it, gravel is purchased with a margin.

Ignoring this coefficient when drawing up a project and carrying out construction work leads to the purchase of an incomplete volume and a deterioration performance characteristics erected structures. With a correctly selected and implemented degree of compaction concrete monoliths, the foundations of buildings and roads can withstand the expected loads.

Compaction rate on site and during transport

Deviation in the volume of rubble loaded and delivered to the end point - known fact, the stronger the vibration during transportation and the further the distance, the higher its degree of compaction. To check the conformity of the amount of material brought in, an ordinary tape measure is most often used. After measuring the body, the resulting volume is divided by the coefficient and compared with the value indicated in the accompanying documentation. Regardless of the size of the fractions, this indicator cannot be less than 1.1, with high requirements for the accuracy of delivery, it is negotiated and prescribed separately in the contract.

If this point is ignored, claims against the supplier are unfounded, according to GOST 8267-93, the parameter does not apply to mandatory characteristics. By default, for crushed stone, it is taken equal to 1.1, the delivered volume is checked at the receiving point, after unloading the material takes a little more space, but over time it shrinks.

The required degree of compaction during the preparation of the foundations of buildings and roads is indicated in the design documentation and depends on the expected weight loads. In practice, it can reach 1.52, the deviation should be minimal (no more than 10%). The ramming is carried out in layers with a thickness limitation of 15-20 cm and the use of different fractions.

Road surface or foundation cushions are poured onto prepared sites, namely, with leveled and compacted soil, without significant level deviations. The first layer is formed from coarse gravel or granite crushed stone, the use of dolomite rocks must be allowed by the project. After preliminary compaction, the pieces are split into smaller fractions, if necessary, up to filling with sand or sand and gravel mixtures. The quality of work is checked separately on each layer.

The compliance of the obtained ramming result with the design one is assessed using special equipment - a density meter. Measurement is carried out subject to the content of no more than 15% of grains with a size of up to 10 mm. The tool is immersed 150 mm strictly vertically, observing the required pressure, the level is calculated by the deviation of the arrow on the device. To eliminate errors, measurements are taken at 3-5 points in different places.

Bulk density of crushed stone of different fractions

In addition to the tamping factor, to determine the exact amount of material required, you need to know the dimensions of the structure to be filled in and the specific gravity of the aggregate. The latter is the ratio of the mass of crushed stone or gravel to the volume they occupy and depends primarily on the strength of the original rock and size.

Specific gravity must be indicated in the product certificate; in the absence of accurate data, it can be found independently by experience. This will require a cylindrical container and scales, the material is poured without ramming and weighed before and after filling. The quantity is found by multiplying the volume of the structure or base by the obtained value and by the degree of compaction indicated in the design documentation.

For example, to fill 1 m2 of a pillow 15 cm thick from gravel with a size of fractions within 20-40 cm, you will need 1370 × 0.15 × 1.1 = 226 kg. Knowing the area of the base being formed, it is easy to find the total volume of the aggregate.

Density indicators are also relevant when selecting proportions for cooking. concrete mixes... For foundation structures, it is recommended to use crushed granite with a particle size of 20-40 mm and a specific gravity of at least 1400 kg / m3. Compaction in this case is not carried out, but attention is drawn to flakiness - for the manufacture of concrete products, a cuboid filler with a low content of irregularly shaped grains is required. Bulk density is used when converting volumetric proportions to mass proportions and vice versa.

stroitel-lab.ru

table, snip, according to GOST fractions 40-70

Crushed stone today is the most practical, cheap, effective, and, accordingly, common materials. It is mined by crushing rocks; most often, raw materials are obtained by blasting in quarries.

In this case, the rock is destroyed into pieces of various sizes, and the compaction coefficient strongly depends on the fraction.

Fraction

Granite crushed stone is the most common option because it has high level resistance to temperature influences and practically does not absorb water. The strength of granite meets all technical requirements... Most popular granite fractions:

fine-grained - 5-15 mm;

small - 5-20 mm;

medium small - 5-40 mm;

medium - 20-40 mm;

large - 40-70 mm.

Each variety has different areas of application, mainly the fine fraction of the slag is used for:

preparation of ballast layers, which are necessary for railway tracks and roads;

added to building mixtures.

Based on what to choose a seal

The compaction coefficient strongly depends on various indicators and characteristics of the material, it is imperative to take into account:

average density, usually set by the manufacturer, but generally ranges from 1.4 to 3 g / cm³. This is one of the key parameters used in the calculations;
flakiness for predicting the plane of rubble;
fractional sorting, smaller size grains - more density;
resistance of the material to frost, depends on the breed;
crushed stone radioactivity. The first class can be used everywhere, and the second only for country roads.

Varieties and characteristics

For construction can be used different kinds crushed stone, the assortment is quite large today, but the properties are also significantly different.

Depending on the type of rock, the following main raw material groups are distinguished:

gravel;
limestone;
granite;
secondary.

Granite rock is the most durable, as it is the material that remains after the magma has cooled. Due to the high strength of the rock, it is difficult to handle. Manufactured in accordance with GOST 8267-93.

Crushed stone of 5-20 mm has become widespread, since it can be used for almost all types of construction.

The gravel variety is more free-flowing, respectively, the compaction coefficient of crushed stone is higher. Obtained by grinding rocks, because of this more cheap stuff but also less durable.

The compaction coefficient is actively used to determine the volume of bulk materials, in particular sand,
but also applies to gravel, soil. The most accurate method for determining compaction is the gravimetric method.

It has not found wide practical application due to the inaccessibility of equipment for weighing large volumes of material or the lack of sufficiently accurate indicators. An alternative option for displaying the coefficient is volumetric accounting.

Factors and properties of construction sand

The compaction coefficient is the dependence of the density, that is, the mass of a certain volume, of the controlled sample to the reference standard.

It should be borne in mind that all types of mechanical, outer seal are capable of acting only on the top layer of the material.

The main types and methods of compaction and their effect on the upper layers of the soil are presented in the table.

To determine the volume of backfill material, it is necessary to take into account the relative compaction factor. This is due to a change in the physical properties of the pit after the sand was pulled out.

When pouring a foundation, you need to know the correct proportions of sand and cement. By going to get acquainted with the proportions of cement and sand for the foundation.

Cement is a special bulk material, which in its composition is a mineral powder. about various brands of cement and their application.

With the help of plaster, the thickness of the walls is increased, which increases their strength. find out how long the plaster dries.

P = ((m - m1) * Pв) / m-m1 + m2-m3, where:

m is the mass of the pycnometer when filled with sand, g;
m1 is the weight of the empty pycnometer, g;
m2 - mass with distilled water, g;
m3 is the weight of the pycnometer with the addition of distilled water and sand, and after getting rid of air bubbles
Pw - water density

In this case, several measurements are carried out, based on the number of samples provided for verification. Results should not deviate more than 0.02 g / cm3. If the received data is large, the arithmetic mean is displayed.

Estimation and calculations of materials, their coefficients are the main component of the construction of any objects, as it helps to understand the amount of material required, and therefore costs.

For the correct budgeting, it is necessary to know the density of the sand, for this, the information provided by the manufacturer, based on surveys, and the relative coefficient of compaction upon delivery are used.

Because of what changes the level of the free-flowing mixture and the degree of compaction

The sand passes through a rammer, not necessarily a special one, possibly in the process of moving. It is quite difficult to calculate the amount of material obtained at the output, taking into account all the variables. For accurate calculation you need to know all the impacts and manipulations carried out with sand.

The final coefficient and degree of compaction depends on various factors:

method of transportation, the more mechanical contact with irregularities, the stronger the seal;
duration of the route, information is available to the consumer;
the presence of damage from mechanical influences;
the amount of impurities. In any case, foreign components in the sand give it more or less weight. The cleaner the sand, the closer the density value is to the reference;
the amount of moisture that has entered.

Immediately after purchasing a batch of sand, it should be checked.

What samples are taken to determine the bulk density of sand for construction

Samples need to be taken:

for a batch of less than 350 tons - 10 samples;
for a batch of 350-700 tons - 10-15 samples;
when ordering more than 700 tons - 20 samples.

The received samples should be taken to a research institution for conducting surveys and comparing the quality with regulatory documents.

Conclusion

The required density strongly depends on the type of work. Basically, compaction is needed to form the foundation, backfill trenches, create a cushion for the roadway, etc. The quality of the rammer must be taken into account, each type of work has different requirements for compaction.

In the construction of highways, a roller is often used; in places that are difficult to access for transport, a vibrating plate of various capacities is used.

Is always the relative indicator of the density coefficient is taken into account, since soil and sand tend to change their indicators based on the level of moisture, the type of sand, fraction and other indicators.

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