Softwood lumber is on average considered lighter than hardwood lumber. They are distinguished by ease of processing and durability - resistance to decay, and therefore are often used for carved facade decoration. In addition, it is from coniferous species that the longest sawn timber (more than 6 meters) is produced. Not surprisingly, 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 to road transport, you can expect a catch. "Fresh" wood can often have an unpredictable weight: lumber, depending on the stage of processing, as well as on the area of \u200b\u200bthe forest where the trees were grown, can vary greatly in properties. Here you need to understand specifically.
The weight of softwood lumber according to GOST and in practice
First of all, humidity plays a decisive role in the properties of wood. Raw wood and dried wood can vary in density by half. This is especially true for conifers.
Raw forest - spruce or pine - resin gives additional mass. Humidity depends on the cutting season, on growing conditions, on the part of the trunk from which lumber is made.
In particular, with regard to pine, a tree harvested after the middle of winter (January) will be 10-20% lighter than an autumn one. If the forest area is located in an area with high standing 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 "sucked" forest - the one from which the resin was previously collected - will be more than 1.5 times lighter than the untouched one. Needless to say, the weight of 1 m3 of freshly cut wood will also depend heavily on the humidity of the climate 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 more likely to be heavier: they are initially more moist and retain more water with the same drying. In addition, according to statistics, the beam turns out to be lighter than boards equal to it in cubic capacity (especially unedged ones), even made from the same log: the core of the trunk from which the beam is cut is naturally looser, boards are made not only from the core.
In a word, the mass of raw softwood lumber differs greatly from the mass of dry lumber. On average, the weight of one cubic meter of dry pine is 470 kg, and that of raw 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 raw spruce is 790 kg.
According to GOST, the standard moisture content for wood is 12%. Under 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 species of conifers: larch belongs to the medium-density varieties of wood, the weight of 1 m3 is 660 kg, it surpasses birch and is almost as good as oak.
It varies over a wide range even for the same tree species. The values of the density (specific gravity) of wood are generalized figures. The practical value of the wood density value differs from the given average table value and this is not an error.
Table of density (specific gravity) of wood
depending on the type of wood
| "Handbook of Aviation Material Masses" ed. "Engineering" Moscow 1975 | Kolominova M.V., Guidelines for students of specialty 250401 "Forest engineering", Ukhta USTU 2010 | |||
| wood species | Density wood, (kg / m 3) |
Limit density wood, (kg / m 3) |
Density wood, (kg / m 3) |
Limit density wood, (kg / m 3) |
| ebony (black) |
1260 | 1260 | --- | --- |
| Bakout (iron) |
1250 | 1170-1390 | 1300 | --- |
| Oak | 810 | 690-1030 | 655 | 570-690 |
| Red tree | 800 | 560-1060 | --- | --- |
| Ash | 750 | 520-950 | 650 | 560-680 |
| Rowan (tree) | 730 | 690-890 | --- | --- |
| Apple tree | 720 | 660-840 | --- | --- |
| Beech | 680 | 620-820 | 650 | 560-680 |
| Acacia | 670 | 580-850 | 770 | 650-800 |
| Elm | 660 | 560-820 | 620 | 535-650 |
| Hornbeam | --- | --- | 760 | 740-795 |
| Larch | 635 | 540-665 | 635 | 540-665 |
| Maple | 650 | 530-810 | 655 | 570-690 |
| Birch | 650 | 510-770 | 620 | 520-640 |
| Pear | 650 | 610-730 | 670 | 585-710 |
| Chestnut | 650 | 600-720 | --- | --- |
| Cedar | 570 | 560-580 | 405 | 360-435 |
| Pine | 520 | 310-760 | 480 | 415-505 |
| Linden | 510 | 440-800 | 470 | 410-495 |
| Alder | 500 | 470-580 | 495 | 430-525 |
| Aspen | 470 | 460-550 | 465 | 400-495 |
| Willow | 490 | 460-590 | 425 | 380-455 |
| Spruce | 450 | 370-750 | 420 | 365-445 |
| Willow | 450 | 420-500 | --- | --- |
| Hazelnut | 430 | 420-450 | --- | --- |
| walnut | --- | --- | 560 | 490-590 |
| Fir | 410 | 350-600 | 350 | 310-375 |
| Bamboo | 400 | 395-405 | --- | --- |
| Poplar | 400 | 390-590 | 425 | 375-455 |
- The table shows the density of wood at a moisture content of 12%.
- The figures in the table are taken from the Handbook of Aviation Material Masses, ed. "Engineering" Moscow 1975
- Updated 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 value of the density (specific gravity) of wood depending on the type of wood. The indicator is taken as the average value of the specific gravity, obtained by summarizing the results of multiple practical measurements. In fact, two tables of wood density are published here, taken from completely different sources. A small difference in indicators clearly indicates the variability of the density (specific gravity) of wood. Analyzing the values of wood density from the above table, it is worth paying attention to the differences between the indicators of the aviation directory and the university manual. For objectivity, the value of the density of wood from both documents is given. With the reader's right to choose the priority of the importance of the primary source.
Of particular surprise is the tabular value of the density larches- 540-665 kg / m 3. Some Internet sources indicate the density of larch, equal to 1450 kg / m 3. Who to believe is not clear, which once again proves the uncertainty and unexploredness of the topic being raised. Larch is a fairly heavy material, but not so heavy that it sinks like a stone in water.
Influence of humidity on the specific gravity of wood
Specific Gravity of Driftwood
It is noteworthy that with an increase in the moisture content of wood, the dependence of the specific gravity of this material on the type of wood decreases. The specific gravity of driftwood (humidity 75-85%) is practically independent of the type of wood and is approximately 920-970 kg/m 3 . This phenomenon is explained quite simply. Voids and pores in wood are filled with water, density ( specific gravity) which is much higher than the density of the displaced air. In its magnitude, the density of water approaches the density, the specific gravity of which practically does not depend on the type of wood. Thus, the specific gravity of pieces of wood soaked in water is less dependent on its species than in the case of dry samples. At this point, it is not superfluous to recall 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 moisture content of 12%):
- Rocks with low density(up to 540 kg / m3) - spruce, pine, fir, cedar, juniper, poplar, linden, willow, aspen, black and white alder, sowing chestnut, white walnut, gray and Manchurian, Amur velvet;
- Breeds of medium density(550-740 kg / m3) - larch, yew, drooping birch, fluffy, black and yellow, oriental and European beech, elm, pear, summer oak, oriental, marsh, Mongolian, elm, elm, maple, hazel, walnut , plane tree, mountain ash, persimmon, apple tree, common ash and Manchurian;
- breeds high density (750 kg / m3 and above) - white and sandy locust, iron birch, Caspian locust, white hickory, hornbeam, chestnut-leaved and Araksinsky oak, iron tree, boxwood, pistachio, hop hornbeam.
The density of wood and its calorific value
Density (specific gravity) of wood is the main indicator of its heating energy value- . The relationship here is direct. The higher the density of the wood structure of a wood species, the more combustible woody substance it contains and the hotter these trees turn out.
When organizing the transportation of timber, the density of a tree is an important indicator in the selection of a timber carrier and calculation of the cost of transportation. This will help to avoid overloading, which will accordingly reduce the penalty.
The density of the material is of particular importance to the weight of m3 of wood, therefore, in order to correctly resolve the issues raised, it is necessary to determine the value of the density. There are two types of density: volume weight(density of a structured physical body) and specific gravity(density of the wood substance).
Volumetric weight of wood
The weight of a cubic meter of wood depends on the type of wood and humidity.Calculator for calculating the volumetric weight of a tree.
Tree White Acacia Birch Beech Elm Oak Hornbeam Spruce Norway Maple Linden Larch Alder Walnut Aspen Siberian Fir Caucasian Fir Scots Pine Cedar Pine Poplar Ash
Volume, m3:
Specific gravity of wood
Wood substance is a mass of solid wood materials without natural voids. This type density is measured in laboratory conditions, as it requires additional measurements that are impossible under normal conditions. For each wood of all types and species of trees, this value is a constant and is 1540 kg/m3. However, wood has a multicellular fibrous structure of a complex type. The walls of the wood substance play the role of a frame in the wood structure. Accordingly, for each breed and species of trees, the cell structures, shapes and sizes of cells vary, as a result of which the specific gravity of the tree will be different, as well as the different weight m3 of the tree.
Also, humidity plays an important role in changing the specific gravity of wood. Thanks to the structure this material, with an increase in humidity, the density of wood also increases. However, this rule does not apply to the density of the wood substance.
| № | wood species | Humidity percentage, % | ||||||||||
| 15 | 20 | 25 | 30 | 40 | 50 | 60 | 70 | 80 | 100 | Fresh* | ||
| 1 | Larch | 670 | 690 | 700 | 710 | 770 | 820 | 880 | 930 | 990 | 1100 | 940 |
| 2 | Poplar | 460 | 470 | 480 | 500 | 540 | 570 | 610 | 650 | 690 | 760 | 700 |
| 3 | Beech | 680 | 690 | 710 | 720 | 780 | 830 | 890 | 950 | 1000 | 1110 | 960 |
| 4 | Elm | 660 | 680 | 690 | 710 | 770 | 820 | 880 | 930 | 990 | 1100 | 940 |
| 5 | Oak | 700 | 720 | 740 | 760 | 820 | 870 | 930 | 990 | 1050 | 1160 | 990 |
| 6 | Hornbeam | 810 | 830 | 840 | 860 | 930 | 990 | 1060 | 1130 | 1190 | 1330 | 1060 |
| 7 | Norway spruce | 450 | 460 | 470 | 490 | 520 | 560 | 600 | 640 | 670 | 750 | 740 |
| 8 | walnut | 600 | 610 | 630 | 650 | 700 | 750 | 800 | 850 | 900 | 1000 | 910 |
| 9 | Linden | 500 | 530 | 540 | 540 | 580 | 620 | 660 | 710 | 750 | 830 | 760 |
| 10 | White acacia | 810 | 830 | 840 | 860 | 930 | 990 | 1060 | 1190 | 1300 | 1330 | 1030 |
| 11 | Alder | 530 | 540 | 560 | 570 | 620 | 660 | 700 | 750 | 790 | 880 | 810 |
| 12 | Maple | 700 | 720 | 740 | 760 | 820 | 870 | 930 | 990 | 1050 | 1160 | 870 |
| 13 | common ash | 690 | 710 | 730 | 740 | 800 | 860 | 920 | 930 | 1030 | 1150 | 960 |
| 14 | Siberian fir | 380 | 390 | 400 | 410 | 440 | 470 | 510 | 540 | 570 | 630 | 680 |
| 15 | Scotch pine | 510 | 520 | 540 | 550 | 590 | 640 | 680 | 720 | 760 | 850 | 820 |
| 16 | Caucasian fir | 440 | 450 | 460 | 480 | 510 | 550 | 580 | 620 | 660 | 730 | 720 |
| 17 | Cedar pine | 440 | 450 | 460 | 480 | 510 | 550 | 580 | 620 | 660 | 730 | 760 |
| 18 | Birch | 640 | 650 | 670 | 680 | 730 | 790 | 840 | 890 | 940 | 1050 | 870 |
| 19 | Aspen | 500 | 510 | 530 | 540 | 580 | 620 | 660 | 710 | 750 | 830 | 760 |
* Fresh. - Freshly cut tree
One of the tasks in developing a draft technological regulation for the Construction and Demolition Waste Management Process is to calculate the mass and volume logging residues formed during the cutting of green spaces (demolition of trees) in the construction or demolition zone.
The official methodology for calculating the mass and volume of logging residues for these purposes in Russian Federation no. The initial data for such calculations are information about cut down trees (species, height and thickness at a height of 1.3 m) and shrubs (young stands)given in the transfer sheet from the composition project documentation to the construction site (demolition).
This article presents a method for calculating the mass and volume of logging residues developed in our company. As a basis for its development, tabular data of the All-Union standards for forest inventory, approved by the Order of the USSR State Committee for Forestry dated February 28, 1989 No. 38, were used.
1) The data of table 17 "Volumes of trunks (in the bark) in young growth in height and diameter at a height of 1.3 m" - to determine the volume of trunks of young shoots and shrubs. As a result of processing the above data to determine the average ratio between the diameter (D), height (h) and volume (V) of one trunk, the design coefficient of shape (Kp from Table 1) was determined, which, with an accuracy of +/- 10%, allows determining the volume of the trunk by formula Vst \u003d Kn * h * pD2 / 4.
2) The data of tables 18 and 19 "Volumes of trunks (in the bark) of tree species in height and diameter at a height of 1.3 m with an average shape factor" - to determine the volume of trunks of various tree species. As a result of processing the given data to determine the average ratio between the diameter (D), height (h) and volume (Vst) of one trunk, the calculated coefficients were determined for some of the tree species listed in the table, which, with an accuracy of +/-10%, allows determining the volume of the trunk according to the formula Vst \u003d Kn * h * pD2 / 4. Estimated shape factors are shown in Table 1
3) Table data 185 “Mass 1 cu. m and the volume of 1 t of wood different breeds"- to determine the mass of wood, the values of the mass of one cubic meter of the corresponding type of wood from the "freshly cut" column, or from the "dry" column - for dead wood, were used.
4) Data from table 206 "Volume of bark, branches, stumps and roots" to determine the volume of branches and branches, as well as stumps and roots as a percentage of the volume of trunks. For the calculation, the average values from the interval given in the tables were used. The volume of branches and branches is 7% of the volume of trunks, the volume of stumps and roots is 23% of the volume of trunks.
5) The data of table 187 "Coefficients of full-wood content of brushwood and khmyz" - to determine the storage volume of twigs and branches from a full-wood volume using a conversion factor equal to 10.
FKKO-2014 contains codes for the following wastes:
1 52 110 01 21 5 Waste of branches, branches, tips from logging
1 52 110 02 21 5 Stump removal waste
1 54 110 01 21 5 Waste of low-value wood (brushwood, deadwood, trunk fragments).
Therefore, the calculation of the mass and volume of logging residues must be calculated by type of waste:
- trunks of trees, young shoots and shrubs cut down according to the counting list can be attributed to waste of low-value wood (brushwood, deadwood, fragments of trunks);
- branches and branches - to the waste of branches, branches, tops from logging;
- stumps and roots - to the waste of uprooting stumps.
For the technological regulation of the Construction and demolition waste management process, it is necessary to calculate the mass of waste, but for temporary storage in storage bins and their removal from the construction site, it is also necessary to estimate the volume of logging residues, and in the storage volume.
The calculation is made using the Excel application. An example of an Excel page table header is shown in Table 2.
The calculation was made in the following order:
1) Filling in the initial data according to the transfer sheet;
column 2 - line number of the recount sheet;
column 3 - tree species;
column 4 - the number of trees;
column 5 - the minimum diameter of the trunk from the interval indicated in the transfer sheet;
column 6 - the only value of the diameter of the trunk indicated in the transfer sheet;
column 7 - the maximum diameter of the trunk from the interval indicated in the transfer sheet;
column 8 - the minimum height of the trunk from the interval indicated in the transfer sheet;
column 9 - the only value of the height of the trunk indicated in the transfer sheet;
column 10 - the maximum height of the trunk from the interval indicated in the transfer sheet;
column 11 - additional number of trunks - if the column "characteristic of the state of green spaces" indicates n trunks for one tree, then column 11 indicates (<значение графы 11>= (n-1)*<значение графы 4>.
2) Calculation of the average value of the diameter of the trunk in the presence of an interval:<среднее значение диаметра ствола (графа 6)> = (<значение минимального диаметра (графа 5)>+<максимальное значение диметра (графа 7)>)/2;
3) Determining the volume of one trunk<объем ствола (графа 12)>produced according to Vst=Kn*h*pD2/4, where Kn is the corresponding shape factor from Table 1, D is the average trunk diameter, h is the average trunk height. Calculation of the volume of one trunk:<объем ствола в куб.м (графа 12)>=Kn* π*(<диаметр ствола в см (графа 6>/100)* (<диаметр ствола в см (графа 6>/100)*< высота ствола в м (графа 9)>/ 4);
4) Calculation of a dense measure of the volume of trunks Vpl \u003d Vst * nst, where nst is the total number of trunks:<плотная мера объема стволов (графа 13)> = <средний объем ствола в куб.м (графа 12)>*(<число деревьев или кустов (графа 4)>+<число дополнительных стволов (графы 11)>). For one bush, the number of additional trunks is taken equal to 5.;
5) Calculation of the folding measure (during storage or transportation, it is necessary to take into account the average amount of space occupied by the trunks of trees or bushes:<складочная мера объема стволов (графа 14)>= <плотная мера объема стволов (графа 13)>*4/n;
6) The calculation of the volume of branches and branches, depending on the volume of the trunk, is carried out in accordance with paragraph d) of this article:<объем сучьев и ветвей в плотной мере (графа 16)> = <плотная мера объема стволов (графа 13)> *<переводной коэффициент (графа 15=0,007)>. In a folding measure - in accordance with paragraph e) of this article:<объем сучьев и ветвей в складочной мере (графа 18)> = <объем сучьев и ветвей в плотной мере (графа 16)>*<переводной коэффициент (графа 17=10)>;
7) The calculation of the volume of stumps and roots from the volume of the trunk is carried out in accordance with paragraph d) of this article:<объем пней и корней в плотной мере (графа 20)> = < плотная мера объема стволов (графа 13)>*<переводной коэффициент (графа 19=0,23)>. In the folding measure, the volume of stumps and roots is taken in double volume:<объем пней и корней в складочной мере (графа 21)> =<объем пней и корней в плотной мере (графа 20)>*2.
8) Calculation of the total volume of wood in a dense measure:<полный объем (графа 22)> = <объем стволов в плотной мере (графа 13)>+<объем сучьев и ветвей в плотной мере (графа 16)>+< объем пней и корней в плотной мере (графа 20)>;
9) Calculation of the total volume of wood in a storage measure (this indicator most objectively allows you to assess the need for the capacity of bodies (containers) Vehicle for the removal of logging residues):<полный объем древесины в складочной мере (графа 23)> = <складочная мера объема стволов (графа 14)>+ <объем сучьев и ветвей в складочной мере (графа 18)>+ <объем пней и корней в складочной мере (графа 21)>
10) The volumetric weight of wood in a dense measure (density in t / m3) is recorded in column 24 in accordance with paragraph c) of this article, for species not listed in table 185 - in accordance with Appendix 3 to SNiP II-25-80 (Density of wood and plywood ).
11) Calculation of the weight of the trunks:<вес стволов (графа 22)> = <объем стволов в плотной мере (графа 13)>*<объемный вес древесины (графа 21)>;
12) Calculation of the weight of branches and branches:<вес сучьев и ветвей (графа 26)> = <объем сучьев и ветвей в плотной мере (графа 16)>*< объемный вес древесины (графа 24)>;
13) Calculation of the weight of stumps and roots:<вес пней и корней (графа 27)> = <объем пней и корней в плотной мере (графа 20)>*< объемный вес древесины (графа 24)>;
14) The total weight of the exported waste (logging residues):<вес вывозимого отхода (графа 28)> = <вес стволов (графа 25)> + <вес сучьев и ветвей (графа 26)>+<вес пней и корней (графа 27)>
Thus, the proposed method makes it possible to calculate the volume (both full and warehouse) and the mass of logging residues with differentiation by type of waste based on the initial data of the counting sheet, as well as to estimate the required volume of storage bins or vehicle bodies and the number of car trips for their export.
WEIGHT OF 1 CUBIC METER (VOLUME WEIGHT) OF BEAM, BOARDS AND MOLDINGS
The weight of lumber (beams, boards, logs), molded products (lining, trim, plinths, etc.) and other wood products depends mainly on the moisture content of the wood and its species.The table shows the weight values of 1 cubic meter of wood (volume weight) depending on the type of wood and its moisture content.
Weight table 1 cu. m (bulk weight) timber, boards, lining made of wood of various species and humidity
Depending on the moisture index, measured as a percentage of the mass of water contained in 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 in a warm, dry room for a long time;
Air-dry wood (moisture content 19-23%) is wood with an equilibrium moisture content, when the moisture content of the wood itself is balanced with that of the surrounding air. This degree of humidity is achieved when long-term storage wood in natural conditions, i.e. without the use of special drying technologies;
raw wood(humidity 24-45%) - this is wood that is in the process of drying from a freshly cut state to an equilibrium state;
Freshly cut and wet wood (moisture content over 45%) is wood that has been recently cut or has been in water for a long time.
WEIGHT OF ONE BEAM, ONE EDGING AND FLOORS, LININGS
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 the data for the most used wood in construction - pine with wet moisture for timber and edged boards and air-dry moisture for floorboards and lining.Weight table of one beam, one board and lining
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