How much does a cube of wood weigh? Carrying out calculations of waste from cutting down trees and shrubs Weight of raw wood

People often ask - are shrubs and shrubs trees? A shrub is a perennial woody plant that reaches a height of 0.7 - 6 meters and differs from trees not only in size, but also because it does not have a tree trunk in the usual sense of the term. If we compare bushes and trees, then from the point of view of the volumetric weight of this woody material, bushes are very similar to tree branches. The practical use and application of bushes in everyday life is approximately the same as that of tree branches. Bushes and branches are very similar in their physical properties: bulk density, specific gravity. Most often, bushes and tree branches are considered waste or garbage suitable for use as household fuel. For example: bushes and branches are used for heating private houses, for which they are burned in special boilers or burned in furnaces. The bushes are predominantly deciduous and lose their leaves in the fall. For landscape design They use beautiful ornamental varieties of shrubs, including evergreen tree-shrubs. Crushed wood from bushes and shrubs is used to make sawdust concrete, wood concrete, and wood concrete.

What is low forest - is it a shrub? Not exactly, the things are similar in appearance, but there is no need to confuse shrubs and small forests. Small woodland is a small forest that does not have business or industrial significance, or ordinary tree species. Small trees often grow in cleared areas, burnt areas, and previously cleared but abandoned areas of forest. When clearing the area of ​​small forests and cutting down small forests, it is convenient to count small trees according to the standards as shrubs. In terms of its volumetric density and specific gravity, chopped small forests are considered analogous to bushes and are considered as shrubs. Small timber and small trees are not considered commercial timber or timber products. Small woodland is not used in the woodworking industry or carpentry. Like shrubs, small forests are considered waste, garbage forest, and can be used for decorative purposes, for decoration and design. Small wood is used as domestic fuel for heating private houses, country houses. After processing (cutting, chopping, sawing), small forests in the form of firewood are burned in furnace boilers, stoves, fireplaces and home hearths. Crushed wood from small forests and small forests is used for the production of sawdust concrete, wood concrete, and wood concrete.

Tree branches or woody twigs are material similar in their physical properties to bushes and small forests. The branches, like small forests, have no business or industrial significance. However, beautiful twigs can be used for crafts, making DIY products, decorating rooms, decorating and designing rooms, gazebos, and interiors. The volumetric weight and density of branches is slightly different from the volumetric density and specific gravity of shrubs (small woodland). However, the differences in the mass of 1 cube (1 cubic meter, 1 cubic meter) are insignificant. The main uses for branches are the same as for wood waste and logging waste - firewood, household fuel, raw materials for processing. Crushed wood branches are used to make sawdust concrete, wood concrete, and wood concrete.

In some cases, the volumetric weight of a grapevine is calculated in such a way that the volumetric density of shrubs and small forests is taken as the density of the vine. Visually, if we judge only by the thickness (diameter) of the grapevine trunk, then it really reminds us of a bush or small forest (especially an old perennial vine). In fact, the specific gravity of the vine is less than that of the branches, since the vine consists not only of woody material, but also includes a large number of pore with air. Therefore, the volumetric weight of the vine is less than that of bushes, small forests, branches, twigs, bushes and small forests. Unlike small forests, grapevine is extremely rarely considered as fuel, since it does not have a high calorific value. Typically, grapevine is used as an ornamental material and raw material for the production of wicker furniture and wicker furniture. In addition, the grapevine is processed into compound feed.

A convenient option for determining the volumetric weight of shrubs, branches, small forests, knots, cuttings and other similar small woody materials can be the example of brushwood. In its physical properties, brushwood is very similar to shrubs and small forests, however, for brushwood, you can indicate the volumetric mass in the case of collecting and storing dry brushwood and wet brushwood. By the way, brushwood is a household fuel. Brushwood, twigs, small damp wood, and standing shrubs, especially shell grass, common willow, and broom. Chop brushwood into wattle fences. Hoop brushwood, hazel, aspen, oak. Brushwood is dry branches and spruce branches lying around in the forest. Brushwood is dry branches and sticks scattered by windbreaks in the forest. Brushwood is fallen tree branches used as fuel and for construction. The branches of brushwood are brittle and do not need to be cut. Brushwood burns well and quickly, it is convenient for quick cooking and heating a home oven. BRUSHWOOD - dry wood, dried wood, dry wood, diseased from the tree, shriveled twigs, branches, crunch, squabble.

While discussing the volumetric weight and density of branches, bushes, small woods, brushwood, vines, bushes and small woods, we forgot to touch coniferous trees. Felled branches of coniferous trees have their own name - spruce branches. The spruce branches are called coniferous - this is the common name. But in some cases clarification is necessary. Then they distinguish pine spruce branches, spruce spruce branches, fir spruce branches, larch spruce branches, etc. The volumetric weight and density of spruce branches are higher than those of the materials discussed above, since spruce branches are always associated with a large number of needles (pine needles).

Table 4. Volumetric weight of shrubs and small forests (weight of a cubic meter, weight of a cubic meter, weight of 1 liter and weight of 1 bucket). Small wood, branches - bulk density and bulk weight of the material. Branches, grapevine, coniferous spruce branches, dry brushwood and wet brushwood, dead wood, pine needles, tree bark.

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 that of wet pine is 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 are 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.

WEIGHT OF 1 CUBIC METER (VOLUMERIUM WEIGHT) OF BEAM, BOARDS AND LOODS

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

Weight table for one beam, one board and lining

NUMBER OF BOOTS, BOARDS AND LINING IN 1 CUBIC. M

Measurement and accounting of felled trees

Each tree can be divided into three parts: trunk, branches and roots. The ratio of these parts to each other in terms of mass varies depending on the breed, age and growing conditions.

Rice. 6. Shape of trees (I) and cross-section of the trunk (II): 1 - tree grown in a dense forest; 2 - in a forest of medium density; 3 - in a sparse forest; AB - largest diameter; CD - smallest

But, as a rule, the stem part makes up the main wood mass, which increases with age.
Numerous observations have shown that in mature, closed stands the mass of stem wood is 60-85%, branches 5-25 and roots 5-30% of the total mass of the tree.

Table 1

The density of the tree stand has a very large influence on this ratio. The trunks in dense stands are taller and in shape in the first half of the tree they are close to a cylinder, in rare ones they are stunted and have a more conical shape, and the crowns are usually large and spreading (Fig. 6). For example, in oak trees grown in the wild in the form of lighthouses, the mass of branches at the age of 50-60 years reaches 50% or more. The trunk of coniferous trees has the best development: spruce, fir, larch and pine.

Taxation characteristics of a tree trunk.

At the bottom the trunk resembles a cylinder, at the top it resembles a cone. To determine the volume of a cylinder and cone, you need to know their height and base area, which can be calculated from its diameter. To determine the volume of a trunk, you need to know its shape, height (length) and thickness (diameter). These elements are the main taxation characteristics of the trunk, and all the others are derived from them. In cross-section, a tree never gives a circle, but only approaches it, but for practical purposes, without any special errors, it is accepted as a circle. It must be remembered that the diameter of the tree must always be measured very carefully, taking it as the average of two mutually perpendicular diameters or from the largest and smallest (see Fig. 6). When determining the height of a felled trunk, it is practically not the length of its axis that is measured, but the curve forming the trunk, since the resulting error is extremely negligible.

Determination of trunk volume.

A felled tree, cleared of twigs and branches, forms a whip or trunk. The volume of a trunk is always less than the volume of a cylinder and greater than the volume of a cone of the same height and base area. By gradually reducing the diameter of the cylinder, you can find one at which its volume is equal to the volume of a tree trunk of the same height. Numerous studies have established that this diameter is approximately the diameter of the middle of the trunk. Therefore, to determine the volume of the trunk, you need to measure its length with a tape measure or other measuring instrument and the diameter in the middle with a measuring fork, then use the measured diameter to calculate the area of ​​the circle and multiply it by the length of the barrel. As a result, we obtain the volume of the measured trunk.
In table 1 shows data for determining the volume of the trunk based on the measured median diameter and height (length). In table 1 shows the most common heights and median diameters of trunks. It can be extended both in length and in diameter. This kind of table is often called cylinder volume tables. Using the table is very simple.
Example. It is required to determine the volume of two trunks with a length of 21 and 11 m with a median diameter of 17 and 12 cm, respectively. To determine the volume of the first trunk according to the table. 1 we find in the first column on the left the number 21 m and on this line a column with a diameter of 17 cm; where they intersect is the number 0.4767. This means that the required volume is 0.4767 m3. The volume of the second trunk is found at the intersection of line 11 and column 12 cm; it is equal to 0.1244 m3.
-It should be noted that when determining the volume by the median diameter, significant errors are possible and in most cases towards an underestimation of the actual volume (sometimes over 10%), but the calculations are made easily and quickly and are quite acceptable for practical purposes. If the volume of the trunk needs to be calculated with greater accuracy, then it is divided into parts and for each of them the volume is determined by the median diameter and length. The shorter these parts are and the more they are cut out of the trunk, the more accurate the result can be obtained based on the total volume. Usually the trunk is divided into 2 sections (Fig. 7). The work is performed as follows. The trunk is marked using a tape measure on the 2nd segments with small notches in their middles, then in the places of the notches, the diameters are measured with a measuring fork and using the table. 1 and 2 find the volumes of all parts, the sum of which gives the volume of the trunk, excluding the top.

Rice. 7. Splitting the tree into 2nd sections

In table Figure 2 shows the volumes of the 2nd segments along the median diameter. The volume of a peak less than 2 m long is usually so small that it is practically not taken into account. The volume of the vertex is calculated using the formula for the volume of a cone - multiplying the area of ​​the base by */3 of the height, i.e. the area of ​​the base should be multiplied by the length and the resulting product divided by three. In table Figure 3 shows data for determining the required volume based on the measured diameter of the base of the apex and its length.
Example. You need to find the volume of a trunk 22 m long. The median diameters of the 2 segments are equal: the first (1 m from the bottom segment) 41; second (3 m) 37; third (5 m) 34; fourth (7 m) 31; fifth (9 m) 29; sixth (11 m) 27; the seventh (13 mU 24; the eighth (15 m) 21; the ninth (17 m) 17 and the tenth (19 m) 12 cm. The diameter of the base of the top (2 m long) is 8 cm.

It varies widely even for one type of wood. The values ​​of the density (specific gravity) of wood are generalized figures. The practical value of wood density differs from the average table value given and this is not an error.

Table of density (specific gravity) of wood
depending on the type of wood

• The table shows the density of wood at a humidity of 12%.
• The table indicators are taken from the “Handbook of Masses of Aviation Materials” ed. "Mechanical Engineering" Moscow 1975
• Corrected on March 31, 2014, according to the method:
  Kolominova M.V., Physical properties of wood: guidelines for students of specialty 250401 “Forest Engineering”, Ukhta: USTU, 2010
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It is generally accepted to indicate the density (specific gravity) of wood depending on the type of wood. The indicator is taken to be the average value of the specific gravity, obtained by summarizing the results of repeated practical measurements. In fact, two wood density tables are published here, taken from completely different sources. A small difference in the indicators clearly indicates the variability of the density (specific gravity) of wood. When analyzing the wood density values ​​from the table above, it is worth paying attention to the differences between the indicators in the aviation reference book and the university manual. For objectivity, the value of wood density from both documents is given. With the right for the reader to choose the priority of the importance of the original source.

Particularly surprising is the tabular density value larches- 540-665 kg/m3. Some online sources indicate the density of larch as 1450 kg/m3. It is not clear who to believe, which once again proves the uncertainty and unknown nature of the topic being raised. Larch is a fairly heavy material, but not so heavy as to sink like a stone in water.

The influence of humidity on the specific gravity of wood

Specific gravity of driftwood

It is noteworthy that with an increase in wood moisture content, the dependence of the specific gravity of this material on the type of wood decreases. The specific gravity of driftwood (humidity 75-85%) practically does not depend on the type of wood and is approximately 920-970 kg/m3. This phenomenon is explained quite simply. The voids and pores in wood are filled with water, the density (specific gravity) of which is much higher than the density of the displaced air. In terms of its value, the density of water approaches the density of , the specific gravity of which practically does not depend on the type of wood. Thus, the specific gravity of pieces of wood soggy in water is less dependent on its species than in the case of dry samples. At this point it is worth remembering that for wood there is a division of classical physical concepts. (cm. )

Wood Density Groups

Conventionally, all tree species are divided into three groups
(according to the density of its wood, at a humidity of 12%):

1. Low density rocks(up to 540 kg/m3) - spruce, pine, fir, cedar, juniper, poplar, linden, willow, aspen, black and white alder, chestnut, white, gray and Manchurian walnut, Amur velvet;
2. Medium density rocks(550-740 kg/m3) - larch, yew, silver birch, downy, black and yellow, eastern and European beech, elm, pear, summer oak, eastern, swamp, Mongolian, elm, elm, maple, hazel, walnut , plane tree, rowan, persimmon, apple tree, common ash and Manchurian;
3. High Density Rocks(750 kg/m3 and above) - white and sand acacia, iron birch, Caspian honey locust, white hickory, hornbeam, chestnut-leaved and Araxinian oak, ironwood, boxwood, pistachio, hop hornbeam.

Density of wood and its calorific value

The density (specific gravity) of wood is the main indicator of its heating energy value - . The dependence here is direct. The higher the density of the wood structure of a tree species, the more combustible wood substance it contains and the hotter such trees are.