Weight of 1 m3 of edged boards. How much does a cube of pine weigh depending on humidity? What is the forest density?
A distinction is made between the specific gravity of wood (solid wood pulp without voids) and the specific gravity of wood as a physical body. The specific gravity of wood matter is above unity and depends little on the type of wood; on average it is taken equal to 1.54. The specific gravity of the wood substance is important in determining the porosity of wood. The conventional volumetric weight has the advantage over the volumetric weight that it does not depend on the amount of shrinkage and does not require recalculation to 15% humidity. This makes it possible to significantly simplify calculations and provide more uniform results when determining the γconditions of several samples.
Classification of rocks by density
The density values of different types of wood differ quite significantly. Based on standard moisture content, rocks are usually divided into three groups:
– low-density species (540 kg/m3 or less): conifers - pine, spruce (all types), fir (all types), cedar (all types), common juniper; from deciduous trees - poplar (all types), linden (all types), willow (all types), black and white alder, chestnut, white, gray and Manchurian walnut, Amur velvet;
– medium density species (540-740 kg/m3): conifers - larch (all types), yew; from deciduous - drooping, fluffy, black and yellow; eastern and European beech, elm, pear, summer oak, eastern, swamp, Mongolian; elm, elm, maple (all types), hazel, walnut, plane tree, rowan, persimmon, apple, common and Manchurian;
– high-density species (750 kg/m3 and above): white and sand acacia, iron acacia, Caspian honey locust, white hickory, hornbeam, chestnut-leaved and Araxinian oak, ironwood, boxwood, pistachio, hopshornbeam.
Among the foreign species, there are those whose wood has both a very low density (balsa - 120 kg/m3) and a very high density (backout - 1300 kg/m3).
The tables of the State System of Standard Reference Data (GSSSD), published by Gosstandart of Russia (“Wood. Indicators of physical and mechanical properties of small samples without defects”), provide more detailed information on the density of wood, indicating the type of tree species and the area of its growth.
The density of bark has been studied much less than that of wood. The available data are very varied.
Comparison of these data with the average density of wood at standard humidity shows that the density of pine bark is 30-35% greater than wood, spruce - 60-65%, and birch - 15-20%.
The influence of wood structure on its properties
The density of wood is also greatly influenced by the water it contains. Firstly, it increases the mass of the sample, and secondly, the swelling of cell walls in water causes a change in the volume of the sample. Therefore, the density of wood is determined either in the absence of water or at a certain mass fraction of it in the wood. Completely dried samples actively absorb water vapor from the surrounding air and in some cases it is more convenient to handle wood samples that contain a known amount of water and are in relative equilibrium with the surrounding atmosphere. In technological calculations, the basic density of wood is sometimes used, which is the ratio of the mass of an absolutely dry wood sample to its volume in the most swollen state. This condition is typical for freshly cut wood and wood that has been in contact with water for a long time. In this case, the basic relative density is actually determined; however, by equating 1 g of displaced water to a volume of 1 cm3, they transform it from a dimensionless quantity into a quantity that has dimension.
Tree species are characterized by certain values of wood density, which are influenced by growing conditions. Depending on the botanical species, the density of wood varies widely. For example, for tree species common in Russia, the density of absolutely dry wood varies from 350 kg/m3 for Siberian fir to 920 kg/m3 for iron birch.
Based on the density of wood at a humidity of 12%, all domestic species are divided into three groups: with low density (540 kg/m3 or less) - spruce, fir, pine, cedar pine, poplar, willow, linden, alder; medium density (550...740 kg/m3) - larch, birch, beech, oak, elm, maple, ash; high density (750 kg/m3 or more) - acacia, hornbeam, certain types of birch, oak, ash. It should be noted that coniferous wood, with the exception of larch and some types of pine, has low density. 
Closely related to this is the property of permeability to liquids and gases. The permeability of wood characterizes its ability to pass liquid or gases under pressure, which is very important for wood processing processes. The permeability of wood is due to the existence in the wood of a system of cell cavities and intercellular spaces communicating through the pores. A dry cell wall, as already noted, has low porosity, and its components are either included in crystalline regions or are in a glassy state, which makes the cell wall practically impermeable to non-polar environments. In polar liquids, cell walls swell greatly and their porosity increases. For technological purposes, water permeability and gas permeability are most important. Since there is a good correlation between these characteristics, and testing wood for gas permeability requires much less time, in practice, to assess the permeability of wood, its gas permeability is often determined.
The permeability of wood, estimated by the mass or volumetric flow rate of a liquid or gas through a unit surface area of a wood sample, is maximum in the axial direction, i.e. along the fibers. It is several times higher than in conifers, since it coincides with the direction of the vessels. The permeability across the fibers is much less and is greatly influenced by the medullary rays. The formation of mature and especially heartwood reduces permeability, and in certain species the heartwood becomes waterproof.
What is the density of oak, beech and other species?
In descriptions of interior doors and the types of trees from which they are made, the term “wood density” often appears. Descriptions are good, but they don't provide as clear an understanding as numbers - what does "a little tighter" mean? Values in the form of numbers give an accurate picture, on the basis of which you yourself can decide which wood is most suitable for making interior doors. 
Before moving on to the numbers, let’s define what wood density is and why you need to know it.
The density of wood is the ratio of its mass to volume. Simply put, the more a cubic meter of wood weighs, the denser it is. The density of wood, called , depends on humidity, so it is customary to operate with values obtained at a humidity of 12%.
We've sorted out the first question, let's move on to the second. The density of wood directly affects two important properties - strength and hygroscopicity. Dense wood has higher strength and, in most cases, hygroscopicity. The latter term means that doors made of high-density wood are more susceptible to changes in humidity - everyone knows that wood tends to absorb moisture and expand. For this reason, doors made of aspen, linden or pine, located at the very bottom of the table, are used in saunas and baths, where beech doors would simply stop closing.
Values are given in grams per cubic centimeter (g/cm3) at 12% humidity. Please note that in some cases average values are given.
Brief description of wood properties: Hornbeam.
Hornbeam is most widely distributed in Europe, Asia Minor and Iran. The wood is shiny, heavy, sticky. Color: whitish-gray. Density: 750 kg/m (cube). Brinell hardness: 3.5.
Lacewood. One of the most beautiful Australian trees. The color is light brown with a characteristic grain. Density: 910-1050 kg/m (cube). Brinell hardness: 5.5. Paduc. with bright positive energy. Color: Light yellowish-red to dark brick-red, mottled with darker lines. Density: 850-950 kg/m (cube). Brinell hardness: 4.2.
Wenge. The homeland of wenge wood is the tropical jungle of West Africa, all the way to Zaire. The structure of the material is large, even-grained, the wood is decorative and at the same time heavy and resistant to pressure and bending. Color: Golden brown to very dark brown with black streaks. Density: 850-900 kg/m (cube). Brinell hardness: 4.1.
Tigerwood (tiger tree). Grows in Western Tropical Africa. Colour: Yellowish-brown, sometimes marked with dark stripes called "veins". Density: 800-900 kg/m (cube). Brinell hardness: 4.1.
Cocobolo. High stability when changing humidity. Color: dark, deep red with black, irregular stripes. Bright, expressive, beautiful texture. Density: 800-980 kg/m (cube). Brinell hardness: 4.35.
Rosewood. The wood is very dense and heavy, polishes well, and sinks in the input. Color: attractive light brown with a violet-lilac tint. Density: 1000 kg/m(cube). Brinell hardness: 5.5.
Yarra. The name of one of more than 500 varieties of Australian eucalyptus. Color: all shades of red, from red-pink to dark red. Over time, the yarra darkens and its color can take on very diverse shades. Density: 820-850 kg/m(cube). Brinell hardness: 5.0.
Pear. The wood is dense, hard, easy to process, and rarely cracks. Color: from yellowish-white to brownish-red. To increase hardness, pear wood is placed in water and kept for a long time, after which it is dried for a long time in natural conditions. After drying, it acquires a brownish tint. Density: 700 kg/m (cube). Brinell hardness: 3.4. Oak (stained). The wood is strong, durable, resistant to external influences. After a long (50 to 300 years) soaking (staining) without oxygen, the wood acquires a velvety black color. Black color.
Bog oak is a precious wood material. For thousands of years, sunken oak trunks were located at the bottom of reservoirs, where, without access to air, during the process of staining they acquired strength not inferior to stone. Nature itself gives it strength, durability and a unique color scheme. Density: 750 kg/m (cube). Brinell hardness: 3.8. Boxwood. The wood is hard as bone, its specific gravity is greater than the specific gravity of water, boxwood sinks in water. Therefore, it is used for the manufacture of parts where significant rigidity is required. Color: light yellow, matte. Density: 1350 kg/m (cube). Brinell hardness: over 8.0. Makassar. A type of ebony common in Southeast Asia. Color: dark brown with black veins. It has a very beautiful texture. Density: 1000 kg/m (cube). Brinell hardness: 7.0.
Eben. In trade there are many varieties of ebony. The rarest and most expensive grows only in the countries of Central Africa. So expensive that payment for it is in kilograms. Export supplies of African ebony are limited and are completely controlled by the governments of the countries where it is mined. The wood is very dense and heavy and sinks in water. Color: dark brown to velvety black with characteristic lighter (or light brown) longitudinal veins. Density: 1200 kg/m (cube). Brinell hardness: over 8.0. Jatoba. It is also called Brazilian cherry. The wood is heavy, durable, hard and at the same time surprisingly elastic. It is difficult to process, but can be ground and polished to an almost mirror-like shine. Color: Density: 960 kg/m (cube). Brinell hardness: 4.8. Zebrano. Grows in Gabon and Cameroon. The wood is hard and heavy. The surface is shiny, the texture is somewhat coarse. Color: light golden with narrow streaks ranging from dark brown to almost black. Density: 900 kg/m (cube). Brinell hardness: 4.5. Kewasingo. It grows from equatorial Africa, from Cameroon and Gabon to the Congo. Tree up to 35-40 meters tall, trunk diameter up to 1.5-2 meters. The wood is red-brown to dark red in color. It has a beautiful texture pattern. Dense, hard, stable. Density: 820-850 kg/m(cube). Brinell hardness: 5.0.
Black hornbeam. Grown in the Caucasus mountains. The tree was felled in winter when sap flow has stopped. The secret of painting is passed down from generation to generation. Black color. Density: 700 kg/m(cube). Brinell hardness: 3.4. Merbau. Grows in Southeast Asia (Malaysia, Indonesia, Philippines). The main advantages of merbau are that it contains oily substances in its pores, is very hard, resistant to moisture and does not dry out much. During use, merbau darkens, especially the light areas, as a result of which the color of the wood as a whole is evened out. Color: brown, from light to dark tones, interspersed with yellow streaks in places. Density: 840 kg/cub.m. Brinell hardness: 4.1. Ash. The wood is heavy, hard with high strength. Possessing toughness and one of the most valuable rocks in the world for the manufacture of sports equipment. Density: 700 kg/m(cube). Brinell hardness: 4.0-4.1.
Density of wood at different humidity levels
One of the most important factors when organizing timber transportation is the density of the tree. It is an important indicator when calculating the cost of transportation and selection of a timber truck.
The weight of wood can be specific or volumetric. Specific gravity - the mass of a unit volume of wood without taking into account species, moisture and other factors - is 1540 kg/m3. Volumetric weight - the mass of a unit volume of wood, taking into account moisture and species. Based on the volumetric weight, the density of the tree can be determined. The density of trees of different species is different. Also, the density of a tree of one species is highly variable, depending on the geographical location and type of forest.
As the moisture content of the wood increases, the density increases. For example, at a humidity of 15% - 0.51 t/m3, and at a humidity of 70% - 0.72 t/m3. According to the degree of humidity, the tree is divided into: absolutely dry (humidity - 0%, only in laboratory conditions), room-dry (humidity up to 10%), air-dry (humidity - 15-20%), freshly cut (humidity 50-100%) , wet (over 100%, when storing wood in water).
The density of wood is as a construction raw material.
Wood density - the ratio of wood mass to volume Рw=Mw/Vw
Density depends on the rock and humidity, usually determined from a table. All tree species are divided into 3 groups:
1)Low-density P<0,5(г.см3)(сосна,ель, (пихта, кедр, осина, ольха, липа, тополь)
2) Medium density 0.5
This property is characterized by the mass of a unit volume of material, and has a dimension in kg/m3 or g/cm3.
a) Density of wood substance pd.v., g/cm, i.e. the density of the cell wall material is equal to: pd.v. = md.v. / vd.v., where md.v. and vd.v. - respectively, the mass, g, and volume, cm3, of the wood substance.
This indicator is equal to 1.53 g/cm3 for all species, since the chemical composition of the cell walls of wood is the same.
b) The density of absolutely dry wood p0 is equal to: p0 = m0 / v0, where m0, v0 are, respectively, the mass and volume of wood at W = 0%.
The density of wood is less than the density of wood substance, since it includes voids (cell cavities and intercellular spaces filled with air).
The relative volume of cavities filled with air characterizes the porosity of wood P: P = (v0 - vd.v.) / v0 * 100, where v0 and vd.v. - respectively, the volume of the sample and the wood substance contained in it at W = 0%. Wood porosity ranges from 40 to 80%.
c) Density of wet wood: pw = mw / vw, where mw and vw are, respectively, the mass and volume of wood at humidity W. The density of wood depends on its moisture content. At humidity W< Wпн плотность изменяется незначительно, а при увеличении влажности выше Wпн наблюдается значительный рост плотности древесины
d) Partial moisture content of wood p`w characterizes the content (mass) of dry wood per unit volume of wet wood: p`w = m0 / vw, where m0 is the mass of absolutely dry wood, g or kg; vw is the volume, cm3 or m3, of wood at a given moisture content W.
e) The basic density of wood is expressed by the ratio of the mass of an absolutely dry sample m0 to its volume at a moisture content equal to or higher than the cell wall saturation limit Vmax: pB = m0 / vmax. This basic indicator of density, which is independent of humidity, is widely used to assess the quality of raw materials in the pulp and paper industry and in other cases.
The density of wood varies over a very wide range. Among the species of Russia and neighboring countries, the wood with very low density is Siberian fir (345), white willow (415), and the most dense is boxwood (1040), pistachio core (1100). The range of changes in the density of foreign wood species is wider: from 100-130 (balsa) to 1300 (backout). Density values here and below are given in kilograms per cubic meter (kg/m3).
According to the density of wood at 12% moisture content, the species are divided into 3 groups: low (P12< 540), средней (550 < P12 < 740) и высокой (P12 >740) wood density.
The volumetric weight of wood also depends on the width of the annual layer. In deciduous trees, the volumetric weight decreases with decreasing width of the annual layers. The greater the average width of the growth ring, the greater the volumetric weight of the same breed. This dependence is very noticeable in ring-pore rocks and somewhat less noticeable in open-pore rocks. In conifers, an inverse relationship is usually observed: the volumetric weight increases with a decrease in the width of the growth rings, although there are exceptions to this rule.
The volumetric weight of wood decreases from the base of the trunk to the top. In middle-aged pines this drop reaches 21% (at a height of 12 m), in old pines it reaches 27% (at a height of 18 m).
The decrease in volumetric weight along the height of the trunk reaches 15% (at the age of 60-70 years, at a height of 12 m).
There is no pattern in changes in the volumetric weight of wood along the diameter of the trunk: in some species the volumetric weight decreases slightly in the direction from the center to the periphery, in others it increases slightly.
A big difference is observed in the volumetric weight of early and late wood. Thus, the ratio of the volumetric weight of early wood to the weight of late wood in Oregon pine is 1: 3, in pine 1: 2.4, in larch 1: 3. Therefore, in coniferous species, the volumetric weight increases with an increase in the content of late wood.
Wood porosity. Wood porosity refers to the volume of pores as a percentage of the total volume of absolutely dry wood. Porosity depends on the volumetric weight of the wood: the higher the volumetric weight, the less porosity.
To approximately determine porosity, you can use the following formula:
C = 100 (1-0.65γ 0)%
where C is the porosity of wood in%, γ 0 is the volumetric weight of absolutely dry wood.
The table shows the weight of 1 m3 of wood relative to the percentage of moisture.
Softwood lumber is on average considered lighter than hardwood lumber. They are distinguished by ease of processing and durability - resistance to rotting, and therefore are often used for carved decoration of facades. In addition, it is from coniferous species that the longest lumber is produced (more than 6 meters). It is not surprising that they are traditionally in high demand.
The weight of lumber depends on the type of wood and humidity.
However, determining their weight is not such a simple matter. Although the main conifers - pine and spruce - are obviously lighter than oak or beech, in fact, if the task is to transport a significant amount of lumber by road, you may be in for a catch. “Fresh” wood can often have a weight that is difficult to predict: lumber, depending on the stage of processing, as well as on the area of the forest where the trees were grown, can vary greatly in properties. Here you need to understand it separately.
Weight of softwood lumber according to GOST and in practice
First of all, moisture plays a decisive role in the properties of wood. Raw wood and dried wood can differ in density by half. This is especially true for coniferous species.
Raw wood - spruce or pine - is given additional mass by resin. Humidity depends on the cutting season, on the growing conditions, and on the part of the trunk from which the lumber is produced.
In particular, as for pine, a tree harvested after mid-winter (January) will be 10-20% lighter than the autumn one. If a forest plot is located in an area with high groundwater (closer than 1.5 m to the surface), the tree will be “overloaded” with water, especially the lower part of the trunk. On the other hand, the “cut” forest - the one from which the resin was previously collected - will turn out to be more than 1.5 times lighter than the untouched one. Needless to say, the weight of 1 m3 of freshly cut timber will also greatly depend on climate humidity and similar circumstances.
In processed form, lumber is more or less equal in weight, but still those made from the lower part of the trunk are likely to be heavier: they are initially more moist and, if dried the same, will retain more water. In addition, according to statistics, timber turns out to be lighter than boards of equal cubic capacity (especially unedged ones), even those made from the same log: the core of the trunk from which the timber is cut is naturally looser, and boards are made not only from the core.
In a word, the mass of wet coniferous lumber differs greatly from the mass of dry timber. On average, the weight of one cubic meter of dry pine is 470 kg, and wet – 890 kg: the difference is almost 2 times. The weight of 1 m3 of dry spruce is 420 kg, and the weight of 1 m3 of wet spruce is 790 kg.
According to GOST, the standard moisture content for wood is 12%. In such conditions, spruce has a density of 450 kg/m3, pine - 520 kg/m3, they belong to light species. Among conifers, Siberian fir is even lighter: 390 kg/m3. Nevertheless, there are also heavier coniferous species: larch is a medium-density type of wood, weighing 1 m3 - 660 kg, it is superior to birch and almost as good as oak.
Nevertheless, if the task is to transport coniferous lumber, then the issue of preliminary weighing should be approached as responsibly as possible: random fluctuations in wood density may well bring the weight beyond the limits of the standards, which is fraught with large fines.
An edged board differs from an unedged board in that its cross-section has the shape of a regular rectangle. This allows you to evenly stack it, pack it into even bundles, and quite
accurately determine the cubic capacity, that is, the volume of packaged materials. If you need to determine the weight of a package, or one cubic meter, it is enough to multiply the volume by the density, which is a reference value and depends on both the type of wood and its humidity, that is, the degree of drying.
For the most commonly used wood, you can create a table showing how much a cube of edged board weighs:
Lumber type
Weight of one cubic meter, kg
damp pine
890
Dry pine
470
Raw spruce
790
Dry spruce
450
As can be seen from the table, humidity has a very significant effect on how much a cube of edged board weighs. This great dependence is due to the fact that it is present in large quantities in the cellular structure, and if it is not dried properly, its rapid evaporation can lead to significant distortions in the geometric shape of the boards and bend them.
As a result, it can be argued that the weight of a cubic meter of edged board can be determined by the type of wood, classifying it into one of the categories.
Light wood species include pine, fir and other conifers, as well as poplar. Their average density, that is, the weight of a cubic meter fluctuates around the figure of 500 kilograms.
Medium species - a cubic meter of ash, beech, birch - weighs about 650 kilograms.
Heavy species, such as oak or hornbeam, have a density of more than 750 kilograms per cubic meter.
How much does one edged board weigh?
How much does one edged board weigh? The most frequently asked question in search engines is how much does one cube weigh, and as a result, one edged board. I continue the series of articles devoted to edged lumber. 
At the insistence of colleagues and regular visitors to the site, I continue the series of articles dedicated to lumber. This article is a continuation of the article “How much does one beam weigh?” We are talking only about pine growing in the territory in the central part of Russia. I’ll immediately make a reservation that pine growing in Siberia has a denser texture, weighs more and costs an order of magnitude more. You can even distinguish it visually, but this is the topic of the next article.
The weight of one cubic meter of freshly cut pine and processed into edged lumber is about 860 kg.
I will present the calculations in the form of a table for 8486 and recall the calculation formulas.
BOARD SECTION IN MM. QUANTITY, PCS. IN 1m3 MATHEMATICAL ACTION IS THE WEIGHT OF ONE BOARD IN KG.
logo Tiu.ru300х50х6000
11.1 860kg: 11.1pcs. 77.5
logo Tiu.ru250х50х6000
13.3 860kg: 13.3pcs. 64.7
logo Tiu.ru200х50х6000
16.6 860kg: 16.6pcs. 51.8
logo Tiu.ru150х50х6000
22.2 860kg: 22.2pcs. 38.7
logo Tiu.ru100х50х6000
33.3 860kg: 33.3pcs. 25.8
logo Tiu.ru200х40х6000
20.8 860kg: 20.8pcs. 41.4
logo Tiu.ru150х40х6000
27.7 860kg: 27.7pcs. 31.04
logo Tiu.ru100х40х6000
41.6 860kg: 41.6pcs. 20.7
logo Tiu.ru150х30х6000
37.0 860kg: 37.0pcs. 23.2
logo Tiu.ru200х25х6000
33.3 860kg: 33.3pcs. 25.8
logo Tiu.ru150х25х6000
44.4 860kg: 44.4pcs. 19.3
logo Tiu.ru100х25х6000
66.6 860kg: 66.6pcs. 12.9
To determine for yourself how much a 4000mm and 3000mm long edged board, or another, will weigh. I will give an example of a calculation formula in which a necessary condition for the calculation is the number of pieces per 1 m3.
For a board let's say 150x25x3000mm:
1: 0.15: 0.025: 3 = 88.8 pcs. in 1m3
860kg. : 88.8 pcs. = 10 kg.
The weight of this board with a section of 150x25 and a length of 3000 mm. 10 kg.
For a board 150x50x4000mm:
1: 0.15: 0.05: 4 = 33.3 pcs. in 1m3
860kg. : 33.3 pcs. = 25.8 kg.
The weight of one board with a section of 150x50 and a length of 4000 mm. 26 kg.
At the end of the article, I would like to specially note that these calculations in Moscow markets are the subject of large and small fraud, so each time you need to personally check the “DECLARED DIMENSIONS OF TIMBER”. Like this! (see photo)
The above calculations in the tables are valid only for lumber of clear “DECLARED SIZES” with the correct geometry, i.e., corresponding to GOST 8486-86.
For the “Aerial or Armenian Option” of timber and boards, which are sold cheaply at all sorts of special sales. prices need a separate approach, because the number of pieces. in 1m3 each time it is necessary to calculate separately in accordance with the actual dimensions of the timber and board.
Specific and volumetric weight of wood
A distinction is made between the specific gravity of wood (solid wood pulp without voids) and the specific gravity of wood as a physical body. The specific gravity of wood matter is above unity and depends little on the type of wood; on average it is taken equal to 1.54. The specific gravity of the wood substance is important in determining the porosity of wood.
Instead of the concept of the specific gravity of wood as a physical body, i.e. the ratio of its weight taken in the same volume at 4°, in practice the volumetric weight of wood is used. Volumetric weight (weight per unit volume of wood) is measured in g/cm3 and is reduced to normal wood moisture content - 15%.
In addition to volumetric weight, sometimes they also use reduced volumetric weight, or conditional volumetric weight. Conditional volumetric weight is the ratio of the weight of a sample in a completely dry state to the volume of the same sample in a freshly chopped state. The value of the conventional volumetric weight is very close to the value of the volumetric weight in an absolutely dry state. The relationship between the conditional volumetric weight (γcond) and the volumetric weight in an absolutely dry state (γ0) is expressed by the formula
γ0 = γcondition/(1-Υ)
where Υ is the total volumetric shrinkage in percent,
γ0 is the volumetric weight of absolutely dry wood.
Volumetric weight of wood.
The conventional volumetric weight has the advantage over the volumetric weight that it does not depend on the amount of shrinkage and does not require recalculation to 15% humidity. This makes it possible to significantly simplify calculations and provide more uniform results when determining the γconditions of several samples.
The volumetric weight of wood depends on humidity, on the width of the annual layer, on the position of the sample in terms of trunk height and diameter. As humidity increases, the volumetric weight increases.
The change in the volumetric weight of wood when dried to a moisture content corresponding to the saturation point of the fibers (23-30%) is proportional to the humidity; after this, the volumetric weight begins to decrease more slowly, as the volume of wood also decreases. When wood moisture content increases, the opposite phenomenon occurs.
The numerical relationship between the volumetric weight of wood and humidity is determined by the following formula:
γw = γ0 (100+W)/(100+(Y0 - Yw))
where γw is the desired volumetric weight at humidity W, γ0 is the volumetric weight in an absolutely dry state, W is the wood moisture content in percent,
Y0 is the total volumetric shrinkage as a percentage when drying to an absolutely dry state and
Yw - volumetric shrinkage as a percentage when drying wood to W% moisture content.
The volumetric weight of wood at a given moisture content can be easily determined with sufficient accuracy using the nomogram proposed by N. S. Selyugin (Fig. 11). Let's assume that we need to determine the weight of 1 m3 of pine wood at a humidity of 80%. According to the table 41a we find the volumetric weight of pine wood at 15% humidity equal to 0.52. On the dotted horizontal line we find the point of volumetric weight 0.52 and from this point we go along the corresponding inclined line of the reduced volumetric weight until it intersects with the horizontal line showing a humidity of 80%. From the intersection point we lower a perpendicular to the horizontal axis, which will show the desired volumetric weight, in this case 0.84. In table 5 shows the weight of wood of some species depending on humidity. furniture restoration
Specific and volumetric weight of wood table Figure 13
Rice. 11. Nomogram for determining the volumetric weight of wood at different humidity levels.
The volumetric weight of wood also depends on the width of the annual layer. In deciduous trees, the volumetric weight decreases with decreasing width of the annual layers. The greater the average width of the growth ring, the greater the volumetric weight of the same breed. This dependence is very noticeable in ring-pore rocks and somewhat less noticeable in open-pore rocks. In conifers, an inverse relationship is usually observed: the volumetric weight increases with a decrease in the width of the growth rings, although there are exceptions to this rule.
The volumetric weight of wood decreases from the base of the trunk to the top. In middle-aged pines this drop reaches 21% (at a height of 12 m), in old pines it reaches 27% (at a height of 18 m).
In birch, the decrease in volumetric weight along the height of the trunk reaches 15% (at the age of 60-70 years, at a height of 12 m).
There is no pattern in changes in the volumetric weight of wood along the diameter of the trunk: in some species the volumetric weight decreases slightly in the direction from the center to the periphery, in others it increases slightly.
A big difference is observed in the volumetric weight of early and late wood. Thus, the ratio of the volumetric weight of early wood to the weight of late wood in Oregon pine is 1: 3, in pine 1: 2.4, in larch 1: 3. Therefore, in coniferous species, the volumetric weight increases with an increase in the content of late wood.
Wood porosity. Wood porosity refers to the volume of pores as a percentage of the total volume of absolutely dry wood. Porosity depends on the volumetric weight of the wood: the higher the volumetric weight, the less porosity.
To approximately determine porosity, you can use the following formula:
C = 100 (1-0.65γ0)%
where C is the porosity of wood in%, γ0 is the volumetric weight of absolutely dry wood.
Table 5 - Approximate weight of 1 m3 of wood of different species in kg
Wood threshold Condition of wood moisture
12-18% 18-23% 23-45% freshly cut
Acacia, beech, hornbeam, oak, ash 700 750 800 1000
Birch, elm, elm, chestnut, larch 600 650 700 900
Willow, alder, aspen, pine 500 550 600 800
Spruce, cedar, linden, fir, poplar 450 500 550 800
The Drova72 company conducted an experiment, we weighed 1 folded cube (storage meter) of birch chopped firewood, natural humidity, ~50%. We will discuss the results of this experiment in more detail below.
This experiment in no way claims to be - "scientific" or "100% objective", rather something between information from the Internet and laboratory research. But nevertheless, this is the first step on the path to truth and objectivity.
Next time we will repeat the experiment and try to find a moisture meter, as well as film the whole process on video.
In short, the results
At humidity ~50% and log length ~50cm:
- 1 folding cube weighs ~561 kg;
- 1 dense cubic cube weighs ~790 kg.
In the text below, we reveal in detail the essence of the experiment. The calculation was made based on information from GOST 3243-88 and the sawmill reference book.
Why do we need this?
A small retreat
The volume of firewood in storage meters is measured by multiplying the length, width and height of the woodpile. But the concept of “1 folded cube of firewood” is quite vague, because... firewood in the woodpile can be stacked with different packing densities and there is no GOST or regulation that would explain what “laying density” is and how to measure it. That is, the same amount of firewood (1 conventional storage meter) can be stacked from ~0.7 to ~1.3 foldometers, depending on the packing density and condition of the logs (their curvature, the presence of knots).
For clarity, look at the photo below. It is obvious that the firewood on the right is stacked thoroughly and the number of logs in such a woodpile is greater than in the one on the left. In both cases, the volume of firewood in the storage meters will be the same, but the mass is different. Those. in fact, the amount of firewood in the photo on the left is less. 
In the photo above, please do not pay attention to the different types of firewood, this image shows the density of firewood stacking in the woodpile.
Specifics
Sometimes our clients and I have disagreements regarding the volume of firewood in storage meters. We brought the firewood for stacking in one volume, the client transferred the firewood to his woodpile, measured it, and the volume turned out to be less than originally stated.
In the example above, disagreements almost always arise due to packing density. So we decided weigh 1 folded cube of birch firewood, and compare its weight (mass) with the data, which are presented in GOST 3243-88 and in the Handbook of Sawmilling, Moscow, Timber Industry Publishing House, 1980.
By comparing the weight of our firewood storage meter with data from the above sources, we will understand whether we are packing the firewood tightly enough into the car before delivering it to the buyer.
Sequencing:
- First we will put 1 folding cube in the woodpile.
- Let's weigh this cube on the scales.
- We compare the resulting weight with data from GOST 3243-88 and the Sawmilling Handbook.
According to various sources, the humidity of freshly cut birch can vary from 60 to 80%. We purchase firewood birch, which was harvested (cut down) 1 to 4 months ago from the moment it was brought to us for subsequent processing. The humidity of birch is on average 40-50%. We will make calculations based on 50% humidity.
In the sawmill reference book, the weight of a dense cube of ordinary birch at a humidity of 50% is 790 kg. To convert the weight of a storage meter into a dense cube (or vice versa), you need to apply a coefficient. We will take it from GOST 3243-88, with a log length of up to 0.5 meters of split hardwood - coefficient is 0.71.
790 * 0.71 = 560.9 kg
Those. The mass of our split birch firewood storage meter must be at least 561 kg.
We weigh
Conclusions and comments
First of all, we wanted to test ourselves, because... Sometimes doubts arose about honesty towards our firewood buyers. Now the doubts are dispelled. Our stacking density and volume of firewood in stacked cubic meters meets the necessary requirements.
If we turn again to the sawmill reference book (Note 1), it is obvious that the weight of 1 folded cube at a humidity of 50% will not always be 560.9 kg, because the weight of one dense cube is 790 kg - this is an average value and can range from 553 kg to 1027 kg. And, therefore, 1 storage meter of birch chopped firewood (taking into account the coefficient of 0.71) can weigh from 392kg to 729kg. This is probably due to the different densities of trees and logs.
Of course, this experiment cannot be considered 100% objective, because At a minimum, a moisture meter is needed to determine humidity. Our forest may have different humidity levels because... There are many suppliers and the procurement and delivery times are different for everyone; accordingly, forest moisture can vary from 30 to 60%.
If you have any suggestions or comments on this material, please write to our email: mail@site.
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WEIGHT OF 1 CUBIC METER (VOLUMERIUM WEIGHT) OF BEAM, BOARDS AND LOODS
The weight of lumber (timbers, boards, logs), moldings (linings, platbands, baseboards, etc.) and other wood products depends mainly on the moisture content of the wood and its species.The table shows the weight of 1 cubic meter of wood (volume weight) depending on the type of wood and its moisture content.
Weight table 1 cu. m (volume weight) timber, boards, linings made of wood of various species and humidity
Depending on the moisture content, measured as a percentage of the mass of water contained in the wood to the mass of dry wood, wood is divided into the following moisture categories:
Dry wood (humidity 10-18%) is wood that has undergone technological drying or has been stored for a long time in a warm, dry room;
Air-dry wood (humidity 19-23%) is wood with equilibrium moisture content, when the moisture content of the wood itself is balanced with the humidity of the surrounding air. This degree of humidity is achieved during long-term storage of wood under natural conditions, i.e. without the use of special drying technologies;
Green wood (humidity 24-45%) is wood that is in the process of drying from a freshly cut state to equilibrium;
Freshly cut and wet wood (moisture content greater than 45%) is wood that has been recently cut or has been in water for a long time.
WEIGHT OF ONE BEAM, ONE EDGED AND FLOORBOARD, LINING
The weight of one beam, board or any molded product also depends on the moisture content of the wood from which they are made and its species. The table shows data for the wood most used in construction - pine with damp moisture for timber and edged boards and air-dry moisture for floorboards and lining.Weight table for one beam, one board and lining
