ASTM D2395-2007ae1 Standard Test Methods for Specific Gravity of Wood and Wood-Based Materials《木材和木基材料比重的标准试验方法》.pdf

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1、Designation: D 2395 07a1Standard Test Methods forSpecific Gravity of Wood and Wood-Based Materials1This standard is issued under the fixed designation D 2395; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisio

2、n. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1NOTEEditorial corrections were made throughout in October 20

3、08.1. Scope1.1 These test methods cover the determination of thespecific gravity of wood and wood-based materials to generallydesired degrees of accuracy and for specimens of differentsizes, shapes, and moisture content conditions. The methodtitle is indicative of the procedures used or the specific

4、 area ofuse.SectionTest Method AVolume by Measurement 7Test Method BVolume by Water Immersion 8Test Method CFlotation Tube 9Test Method DForstner Bit 10Test Method EIncrement Core 11Test Method FChips 121.2 This standard does not purport to address all of thesafety concerns, if any, associated with

5、its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 9 Terminology Relating to Wood and Wood-Based Prod-uctsD 2555 Pract

6、ice for Establishing Clear Wood Strength Val-uesD 4442 Test Methods for Direct Moisture Content Measure-ment of Wood and Wood-Base MaterialsD 4444 Test Method for Laboratory Standardization andCalibration of Hand-Held Moisture MetersE 1547 Terminology Relating to Industrial and SpecialtyChemicals2.2

7、 Other Standards:CAN/CSA O86 Engineering Design in Wood3ANSI/AF in larger speci-mens the number of measurements will depend on the unifor-mity of the specimen, but at least three measurements of eachdimension will be required.7.2.2 MassDetermine the initial mass (mM) of the speci-men at the time of

8、test in accordance with 6.2.7.2.3 Moisture ContentDetermine the moisture content(M) of the specimen to permit description of the basis on whichthe specific gravity is computed. Test Methods D 4442 andD 4444 indicate procedures that should be used.7.2.4 Small SpecimensThe entire specimen may be usedf

9、or determination of moisture content.7.2.5 Intermediate SpecimensWhen the specimen is of asize that is unsuitable for moisture content determinations (thetime to oven-dry to constant mass would be excessive), asegment may be cut from the specimen for a moisture contentspecimen. Select this segment s

10、o that its moisture content isrepresentative of that of the larger specimen. Where possible insolid wood elements, the moisture content specimen shall be offull cross-sectional dimensions and 1 in. (25 mm) in length(parallel to grain). In sheet materials the specimen shall beequal in thickness to th

11、e thickness of the material and 3 by 6 in.(76 by 122 mm) in size.7.2.6 Structural ElementsIn full-sized members, deter-mine the moisture content from a segment cut from themember. It shall be of full cross-sectional dimensions and 1 in.(25 mm) in length (parallel to grain), and shall be selected fro

12、ma representative area of the member. To avoid the effects of enddrying, cut the specimen at least 18 in. (457 mm) in from theend of the member.7.2.7 Special SituationsWhere the specimen or elementcannot be cut to secure a moisture content segment, anapproximate moisture content may be obtained thro

13、ugh the useof a moisture meter which is used in accordance with themanufacturers recommendations. Since the moisture contentD 2395 07a12value is approximate, it should be recognized that the specificgravity value obtained will also be approximate.7.2.8 Specimen PreparationWhen the moisture contentsp

14、ecimen is a portion of the element, remove all loose particlesfrom the specimen and determine the initial mass (mM)inaccordance with 6.2.7.3 DryingOven-dry the moisture content specimen toconstant mass in accordance with 6.2, and determine theoven-dry mass (m0).8. TEST METHOD BVOLUME BY WATERIMMERSI

15、ON8.1 Applicability:8.1.1 Type of SpecimenThis procedure is particularlyadaptable to specimens of irregular shape or having a roughsurface. Limitations on specimen size are based primarily onsize of immersion tanks available. In small size specimens, lessthan 1 cm3in volume, air bubbles adhering to

16、the specimensurface can result in considerable error in volume measurementand thus to the computed specific gravity value. Freshly cutgreen wood will not absorb appreciable quantities of waterduring the brief immersion period.As soon as any drying of thewood has taken place however, the surface must

17、 be sealedbefore immersion in water or else the volumetric displacementof the wood specimen will be in error in an amount equal to thevolume of water absorbed by the wood.8.2 Procedures:8.2.1 MassDetermine the initial mass (mM) of the speci-men at time of test in accordance with 6.2.8.2.2 VolumeDete

18、rmine the volume of the specimen byone of the following modes. Volume may be determined in theas received condition if the specimen is green; or in the asreceived condition if the specimen is partially dry or afteroven-drying if the pores are adequately sealed (see 8.2.2.5).Determine the volume of t

19、he specimen by measuring thevolume of water displaced or by determining the mass of thewater displaced. The mass in grams is numerically equal to thevolume in cubic centimetres.8.2.2.1 Mode IPlace the specimen in a tank of knownvolume and add sufficient water to fill the tank. Then removethe specime

20、n and determine the volume of water remaining.The tank volume less the volume of water remaining is equalto the volume of the specimen. The relationship betweenspecimen volume and tank volume shall be such that theprecision of specimen volume measurement is high.8.2.2.2 Mode IIPlace a container hold

21、ing enough water tocompletely submerge the specimen on one pan of a balance asshown in Fig. 1. Then balance the combined mass of thecontainer and water with mass added to the other pan. Hold thespecimen so that it is completely submerged without touchingthe sides of the container by means of a sharp

22、, pointed, slenderrod and balance the scales again. The mass added to restorebalance is equal to the mass of water displaced by thespecimen.Alternatively, an automatic balance may be used andwill greatly facilitate the speed of such measurements. If verysmall specimens are used, the accuracy of resu

23、lting data islikely to be low.8.2.2.3 Mode IIIPlace a container holding enough waterto completely submerge the specimen below one pan of abalance as shown in Fig. 2. The container shall be sufficientlylarge so that immersion of the specimen causes no materialchange in water level. Suspend a wire bas

24、ket of sufficient massto hold the specimen submerged from this same pan andimmerse it in the water. Balance the mass of the basket whenfreely immersed with mass added to the other scale pan. Weighthe specimen in air. Place the specimen in the basket and holdit completely submerged without touching t

25、he container whilebalancing the scales again. The mass added to restore balance,if the specimen is lighter than water, plus the mass of thespecimen in air equals the volume of water displaced. If thespecimen is heavier than water, subtract the mass added torestore balance from the mass of the specim

26、en in air todetermine the volume of water displaced.8.2.2.4 Mode IVImmerse the specimen, of an elongatedshape, in a graduated tube having a cross section only slightlylarger than that of the specimen as shown in Fig. 3. Read thewater level in the tube, preferably to an even graduation mark,before im

27、mersing the specimen. Immerse the specimen, hold itsubmerged with a slender pointed rod if necessary, anddetermine the water level again. The difference in water levelis equal to the volume of the specimen.8.2.2.5 Surface Treatment of SpecimenGreen specimensmay be immersed in water for volume determ

28、inations withoutmaterial absorption of water that will affect volume determi-nations. Dip air-dry or oven-dry specimens in hot paraffin waxbefore making volume determinations. After the wax dip,FIG. 1 Diagrammatic Sketch of Apparatus Used to Measure Volume of Specimens by Test Method B-IID 2395 07a1

29、3weigh the specimen again and use this mass in conjunctionwith the immersed mass for determining volume in Mode IIand Mode III (8.2.2.2 and 8.2.2.3). Alternatively, softwoodspecimens or hardwood specimens with small pores may bedipped in a solution of paraffin wax in carbon tetrachloride: 1oz of par

30、affin wax in 260 in.3of carbon tetrachloride (1 g ofparaffin wax in 150 cm3of carbon tetrachloride). Beforeimmersion, allow the carbon tetrachloride to evaporate for afew minutes. The gain in mass due to the thin film of waxdeposited is negligible. This test method may be effectivelyused on air-dry

31、specimens since thin wax film does not appearto affect shrinkage when the specimen is oven-dried.(WarningObserve necessary precautions to ensure properventilation when carbon tetrachloride is used.)8.2.3 Moisture ContentDetermine the moisture content(M) of the specimen to permit description of the b

32、asis on whichthe specific gravity is computed.8.2.3.1 SpecimenThe entire specimen or a representativesegment may be used for the moisture content determination.Remove all loose particles from the specimen and determinethe initial mass (mM) in accordance with 6.2.8.2.4 DryingOven-dry the moisture con

33、tent specimen toconstant mass in accordance with 6.2 and determine theoven-dry mass (m0).9. TEST METHOD CFLOTATION TUBE9.1 Applicability:9.1.1 Type of SpecimenThis procedure provides a rapidmeans for obtaining an approximate specific gravity for anelongated specimen of uniform cross section and know

34、nmoisture content.NOTE 1Estimates of specific gravity to the nearest 0.02 can be readilymade.9.2 Procedures:9.2.1 Specimen PreparationThe specimen shall be slen-der and of uniform cross section, preferably about 1 in. (25mm) on a side and 10 in. (254 mm) long. The moisture contentmay be any known va

35、lue.9.2.2 MeasurementPlace the specimen in a slender cylin-der filled with water and allow it to float in as nearly a verticalposition as possible (Fig. 4). The cylinder diameter shall beslightly larger than the specimen cross section, and the speci-men shall not touch the cylinder wall until immers

36、ed as far asit will go. With the specimen floating in an upright position,quickly mark the water level on the specimen to avoidexcessive absorption of water by the specimen.10. TEST METHOD DFORSTNER BIT10.1 Applicability:10.1.1 Type of SpecimenThis procedure is particularlyadaptable for determining

37、the specific gravity of logs, timbers,or any in-place elements from which it would be difficult tosaw a more conventional sample. The Forstner-type bit doesnot have a lead screw, and volume of material can be readilyFIG. 2 Diagrammatic Sketch of Apparatus Used to Measure Volume of Specimens by Test

38、Method B-IIIFIG. 3 Test Method of Measuring Volume of ElongatedSpecimens Using a Graduated TubeD 2395 07a14obtained from the diameter of the bit and the depth of the hole.Care shall be taken to collect all of the shavings.10.2 Procedures:10.2.1 VolumeObtain the volume of specimen material byboring a

39、 hole into the element in question with a Forstner-typebit. The diameter of hole and depth of boring shall be such thatan adequate sample is obtained without damage to the element.Accurately measure the diameter of the bit and depth of thehole. Use these dimensions to calculate the specimen volume.1

40、0.2.2 MassCarefully collect all of the chips obtained byboring and immediately weigh them to determine the initialmass (mM).10.2.3 Moisture ContentDetermine the moisture content(M) to permit description of the basis on which the specificgravity is computed.10.2.4 DryingOven-dry the chips to constant

41、 mass inaccordance with 6.2 and determine the oven-dry mass (m0).11. TEST METHOD EINCREMENT CORES11.1 Applicability:11.1.1 This procedure is particularly adaptable for obtainingspecimens to determine the specific gravity of standing treesbut is also suitable for use on logs, poles, piles, or otherst

42、ructural elements. Since only a pencil-sized hole is made inthe member in question, it has no material effect on theproperties of the member and can be easily sealed.11.2 Procedures:11.2.1 VolumeObtain the specimen material by extractinga core from the member by means of a standard incrementborer. O

43、btain the volume from the diameter of the cutting edgeof the increment borer and measure the length of the coreimmediately after it is removed from the member. Handle thecore carefully to prevent damage or loss of any portion.11.2.2 MassWhen the moisture content of the element isdesired, weigh the i

44、ncrement core immediately after the lengthis measured in order to obtain the initial mass (mM). If this isimpossible, the core must be protectively wrapped to preventloss of moisture.11.2.3 DryingOven-dry the increment core to constantmass in accordance with 6.2 and determine the oven-dry mass(m0).1

45、2. TEST METHOD FCHIPS512.1 Applicability:12.1.1 This procedure is specifically designed to determinethe specific gravity of wood chips. This is most often obtainedon a green volume, oven-dry mass basis, although otherspecific gravity values can be obtained.12.2 Procedures:12.2.1 SpecimenSelect a rep

46、resentative sample of chipsweighing 0.66 to 0.77 lb (approximately 300 to 350 g) for test.Remove sawdust and undersized chips by shaking on athree-mesh sieve.12.2.2 MassObtain the initial mass (mM) of the chips inaccordance with 6.2.12.2.3 VolumeSubmerge the chips in water at room tem-perature for a

47、t least1htoensure that they are at their greenvolume and will not absorb water during volume measurement.Then remove them from the water, allow them to drain in awire-mesh basket, and place them in the centrifuge basket.Centrifuge the chips from 800 to 1200 rpm for 1 to 4 min.12.2.3.1 Place a contai

48、ner holding enough water to freelysubmerge the chip holder on one scale pan and balance it.Submerge the empty chip holder, except for its wire handle, inthe water container. The chip holder must not touch the sides orbottom of the container, and shall be balanced by mass whichrepresent the volume of

49、 water equivalent to that of the emptychip holder. Transfer the chips to the chip holder and slowlylower them into the container of water, being careful to removeany entrapped air. Balance the scale and obtain the massnecessary to balance the volume of water equal to the volumeof chips (V).12.2.4 DryingRemove the chips and oven-dry to constantmass in accordance with 6.2 to determine the oven-dry mass(m0).13. Calculation13.1 Moisture Content (M) or Final (Oven-Dry) Mass (m0):13.1.1 If Test Methods D 4442 are used, the moistureconten