1、Designation:D494404 Designation: D4944 11Standard Test Method forField Determination of Water (Moisture) Content of Soil bythe Calcium Carbide Gas Pressure Tester1This standard is issued under the fixed designation D4944; the number immediately following the designation indicates the year oforiginal
2、 adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method outlines procedures for determining the water (mo
3、isture) content of soil by chemical reaction using calciumcarbide as a reagent to react with the available water in the soil producing a gas. A measurement is made of the gas pressureproduced when a specified mass of wet or moist soil is placed in a testing device with an appropriate volume of reage
4、nt and mixed.1.2 This test method is not intended as a replacement for Test Method D2216; but as a supplement when rapid results arerequired, when testing is done in field locations, or where an oven is not practical for use. Test Method D2216 is to be used asthe test method to compare for accuracy
5、checks and correction.1.3 This test method is applicable for most soils. Calcium carbide, used as a reagent, reacts with water as it is mixed with thesoil by shaking and agitating with the aid of steel balls in the apparatus. To produce accurate results, the reagent must react withall the water whic
6、h is not chemically hydrated with soil minerals or compounds in the soil. Some highly plastic clay soils or othersoils not friable enough to break up may not produce representative results because some of the water may be trapped inside soilclods or clumps which cannot come in contact with the reage
7、nt. There may be some soils containing certain compounds orchemicals that will react unpredictably with the reagent and give erroneous results. Any such problem will become evident ascalibration or check tests with Test Method D2216 are made. Some soils containing compounds or minerals that dehydrat
8、e withheat (such as gypsum) which are to have special temperature control with Test Method D2216 may not be affected (dehydrated)in this test method.1.4 This test method is limited to using calcium carbide moisture test equipment made for 20 g, or larger, soil specimens andto testing soil which cont
9、ains particles no larger than the No. 4 Standard sieve size.1.51.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.5.1 Cited sieve sizes are the standard sieve sizes given in Table 1 of Specification E11.1.6 All observed and
10、 calculated values shall conform to the guidelines for significant digits and rounding established in PracticeD6026 unless superseded by this standard.1.6.1 The procedures used to specify how data are collected, recorded or calculated in this standard are regarded as the industrystandard. In additio
11、n they are representative of the significant digits that generally should be retained. The procedures used do notconsider material variation, purpose for obtaining the data, special purpose studies, or any considerations for the users objectives;it is common practice to increase or reduce significan
12、t digits of reported data to be commensurate with these considerations. It isbeyond the scope of this standard to consider significant digits used in analytical methods for engineering design.1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. I
13、t is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. For specific hazards statements, see Section 7.2. Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil,
14、 Rock, and Contained FluidsD2216 Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by MassD3740 Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspection of Soil and Rock as Used inEngineering Design and Construction1This test method is
15、under the jurisdiction ofASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.08 on Special and ConstructionControl Tests.Current edition approved JulyNov. 1, 2004.2011. Published July 2004.December 2011. Originally approved in 1989. Last previous edition approved
16、 in 19982004 asD494498.D494404. DOI: 10.1520/D4944-04.10.1520/D4944-11.2For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. ForAnnual Book ofASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM w
17、ebsite.1This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult p
18、rior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA
19、19428-2959, United States.D4753 Guide for Evaluating, Selecting, and Specifying Balances and Standard Masses for Use in Soil, Rock, and ConstructionMaterials TestingD6026 Practice for Using Significant Digits in Geotechnical DataE11 Specification for Woven Wire Test Sieve Cloth and Test Sieves Speci
20、fication for Woven Wire Test Sieve Cloth and TestSievesE177 Practice for Use of the Terms Precision and Bias in ASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method3. Terminology3.1 Definitions of terms used in this test method can be fou
21、nd in Terminology D653.4. Summary of Test Method4.1 A measured volume of calcium carbide, in excess of that needed to react with the water, is placed in the testing apparatusalong with two steel balls and a representative specimen of soil having all particles smaller than the No. 4 sieve size and ha
22、vinga mass equal to that specified by the manufacturer of the instrument or equipment. The apparatus is shaken vigorously in a rotatingmotion so the calcium carbide reagent can contact all the available water in the soil. Acetylene gas is produced proportionally tothe amount of available water prese
23、nt. The apparent water content is read from a pressure gauge on the apparatus calibrated to readin percent water content for the mass of soil specified.4.2 A calibration curve is developed for each instrument and each soil type by plotting the pressure gauge reading and the watercontent determined f
24、rom Test Method D2216 using representative specimens of the soil. The calibration curve is used to determinea corrected water content value for subsequent tests on the same type of soil.5. Significance and Use5.1 The water content of soil is used throughout geotechnical engineering practice, both in
25、 the laboratory and in the field.Results are sometimes needed within a short time period and in locations where it is not practical to install an oven or to transportsamples to an oven. This test method is used for these occasions.5.2 The results of this test have been used for field control of comp
26、acted embankments or other earth structures such as in thedetermination of water content for control of soil moisture and dry density within a specified range.5.3 This test method requires specimens consisting of soil having all particles smaller than the No. 4 sieve size.5.4 This test method may no
27、t be as accurate as other accepted methods such as Test Method D2216. Inaccuracies may resultbecause specimens are too small to properly represent the total soil, from clumps of soil not breaking up to expose all the availablewater to the reagent and from other inherent procedural, equipment or proc
28、ess inaccuracies. Therefore, other methods may be moreappropriate when highly accurate results are required, or when the use of test results is sensitive to minor variations in the valuesobtained.NOTE 1The quality of the result produced by this standard is dependent on the competence of the personne
29、l performing it, and the suitability of theequipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objectivetesting/sampling/inspection. Users of this standard are cautioned that compliance with Practice D3740 does not in its
30、elf ensure reliable results. Reliableresults depend on many factors; Practice D3740 provides a means of evaluating some of those factors.6. Apparatus6.1Calcium Carbide Pressure Tester Set (including testing chamber with attached pressure gage and a set of tared balances), forwater content testing of
31、 specimens having a mass of at least 20 g, (10 g for the half measure required for wetter specimens). Testersthat use a smaller mass are available, but are considered too inaccurate for this standard. The testing chamber with pressure gageand the balances are calibrated as a set (see Section Apparat
32、us6.1 Calcium Carbide Pressure Tester Set Including:6.1.1 Testing chamber with attached pressure gauge.6.1.2 A set of tared manual balances or portable electronic balance meeting the requirements of a GP2 of Specification D4753.NOTE 2Testers that use a smaller mass are available, but are considered
33、too inaccurate for this standard. The testing chamber with pressure gaugeand the balances are calibrated as a set (see Section 8). A typical apparatus is shown in Fig. 1.6.1.3 Carrying case.6.1.4 Typical apparatus configurations are shown in Fig. 1.6.2 Small Scoop, for measuring reagent.6.3 Two Stee
34、l Balls, (manufacturer supplied).6.4 Brush and Cloth, for cleaning and other incidental items.6.5 Sieve, No. 4 (4.75 mm), conforming to the requirements of Specification E11.6.6 Calcium Carbide Reagent, finely pulverized, of a grade that will readily combine with the available sample moisture andis
35、capable of producing acetylene gas in the amount of at least 0.14 cubic meters/kg (2.25 cu ft/lb). It is best to purchase calciumcarbide in small containers with air tight replaceable lids, to store it in a dry place, to keep the lid on the container at all times exceptD4944 112when measuring out a
36、portion for use in a test, and to use a complete container before opening a new one. Calcium carbide qualitywill deteriorate with time after it becomes exposed to the atmosphere or any source of moisture. Periodic purchase of a new supplyis recommended.6.7 Miscellaneous Clothing or Safety Equipment,
37、 such as goggles to protect the operator (see 7.2).6.8 Equipment, as listed in Test Method D2216, for performing comparison tests to make calibration curves.NOTE 23Calibration kits are available from manufacturers for testing gasket leakage and for calibrating the gauge. Periodic checks for gasket l
38、eakageare recommended. The gasket should be changed when leakage is suspected. Gauge calibration problems can usually be detected as the instrumentcalibration curves are made (see Section 8). When the gauge needs adjusting, any good quality calibrating gauge can be used.7. Safety Hazards7.1 When com
39、bined with water, the calcium carbide reagent produces a highly flammable or explosive acetylene gas. Testingshould not be carried out in confined spaces or in the vicinity of an open flame, embers or other source of heat that can causecombustion. Care should be exercised when releasing the gas from
40、 the apparatus to direct it away from the body. Lighted cigarettes,hot objects or open flames are extremely dangerous in the area of testing.7.2 As an added precaution, the operator should use a dust mask, clothing with long sleeves, gloves and goggles to keep thereagent from irritating the eyes, re
41、spiratory system, or hands and arms.7.3 Attempts to test excessively wet soils or improper use of the equipment, such as adding water to the testing chamber, couldcause pressures to exceed the safe level for the apparatus. This may cause damage to the equipment and an unsafe condition forthe operato
42、r.7.4 Care should be taken not to dispose or place a significant amount of the calcium carbide reagent where it may contact waterbecause it will produce an explosive gas.7.5 Calcium carbide is classified as a hazardous material and the user should conform to appropriate regulations regarding theuse,
43、 storage, handling and transportation of calcium carbide.8. Calibration8.1 The manufacturer-supplied equipment set, including the testing chamber with attached gauge and the balance scales, arecalibrated as a unit and paired together for the testing procedure.8.2 Calibration curves must be developed
44、 for each equipment set using the general soil types to be tested and the expected watercontent range of the soil. As new materials are introduced, further calibration is needed to extend the curve data for the specificinstrument. If tests are made over a long period of time on the same soil, a new
45、calibration curve should be made periodically, notexceeding 12 months. Before a new batch of reagent is used for testing, two checkpoints shall be compared to the existing curve.If variation is exceeded by more than 1.0 % of moisture, a new calibration curve shall be established.8.3 Calibration curv
46、es are produced by selecting several samples representing the range of soil materials to be tested and havinga relatively wide range of water content. Each sample is carefully divided into two specimens by quartering procedures or use ofa sample splitter. Taking care to not lose any moisture, one sp
47、ecimen is tested in accordance with the procedure of this test method(see 10.1-10.6) without using a calibration curve, and the other specimen is tested in accordance with Test Method D2216.8.4 The results of the oven dry water content determined by Test Method D2216 from all the selected samples ar
48、e plotted versusthe gauge reading from the calcium carbide tester for the corresponding test specimen pair. A best fit curve is plotted through theFIG. 1 Typical Calcium Carbide Gas Pressure Test Apparatus for Water Content of SoilFIG. 1a (left) Apparatus Set with Manual Tared BalanceFIG. 1b (right)
49、 Apparatus Set with Portable Electronic BalanceD4944 113points to form a calibration curve for each soil type. Comparisons should be relatively consistent. A wide scatter in data indicatesthat either this test method or Test Method D2216 is not applicable to the soil or conditions. Fig. 2 shows a typical calibrationcurve.8.5A8.5 A comparison of this test method with Test Method D2216 for a given soil can be made by using the calibration curve.Points that plot off the curve indicate deviations. Standard and maximum deviations can be determined if desired.9. Sampling9.1 For wat
