1、MANUAL OF CEMENT TESTING1INTRODUCTIONThis Manual of Cement Testing is intended to supplementnot in any way to supersedethe variousASTM standard methods of sampling and physical testing of hydraulic cement. This manual wasprepared by Committee C-1 on Cement and has been accepted by the Society for pu
2、blication asinformation only. The manual is not a part of the ASTM methods.The ASTM standard methods of testing cement are essential adjuncts to the specifications, becausefaulty test methods may lead to erroneous conclusions as to the quality of the cement.Precautionary statements are found in many
3、 of the test methods. Before using a test method forcement testing, the precautionary statement should be noted and clearly understood. See Section 57for safety precautions.The approved test methods are frequently revised, sometimes as often as twice a year. The cementtester must be sure the latest
4、revision of the test method is used. A test method or other ASTM standardis revised and promulgated in the following manner. After a document, based on technical merit, haspassed the ASTM Society letter ballot, which is published in the monthly issue of the ASTMStandardization News, it goes to the C
5、ommittee on Standards. This standing committee of the ASTMBoard of Directors determines if the procedural requirements of the Society have been met. Iffavorable action is taken, the document is approved as a standard. This is the date when the newstandard is officially in effect. An announcement in
6、a later issue of the ASTM Standardization Newsnotifies individuals of its approval and the availability of the standard in published form. The revisedtest method should then be used when testing is specified to be performed by the latest test method.Existing methods of testing cement are, at best, c
7、rude tools, and it must not be expected that exactagreement will be secured in tests by different operators, or by the same operator at different times,even when the tests are made on the same sample and under the same conditions. Many steps areinvolved in making cement tests, and the results are so
8、metimes greatly influenced by seemingly minorvariations in procedure.It is the purpose of this manual to emphasize those factors which may affect results of tests, and tocall attention to less apparent influences which are important but which are sometimes overlooked.The ASTM specifications for ceme
9、nt are intended to set forth minimum requirements that must bemet. Cement testing laboratories should have on hand copies of current ASTM specifications forcements, as well as the standard methods of sampling and testing cement. The cement testers shouldbe thoroughly familiar with these specificatio
10、ns and methods, and should use every care to follow thestandards strictly and maintain their testing equipment in good condition. If careless methods andfaulty equipment are used, and short-cuts made, the results may lead to the rejection of a good product,or, on the other hand, to the acceptance of
11、 a product that may not conform to the specificationrequirements.It is suggested that the different cement testers in a given city or district arrange to carry out testson the same cement and exchange results. To be of the greatest value, such tests should be made notonly by each operator in his lab
12、oratory but also by all operators in a single laboratory where theequipment and test conditions are identical. Each operator should repeat his tests on several differentdays to see how closely he can check his own results. This procedure will do more than anything elseto create an interest in standa
13、rd methods and will be found effective in eliminating erroneous practicesand in calling attention to defective apparatus. A suggested course of training for cement testers isgiven in Section 55.1This manual is under the jurisdiction of ASTM Committee C01 on Cement and is the direct responsibility of
14、 Subcommittee C01.97 on Manual for Cement Testing.Published as information, June, 1932; revised, 1944, 1946, 1950, 1952, 1954, 1955, 1956, 1958, 1960, 1968, 1986, 1989, 1990 and 1992; editorially corrected 1970, 1971,1972, 1975, 1977, 1978, 1981, 1986, 2000, and 2002.1The subjects covered in this ma
15、nual appear in the following order:SectionsSampling 1 and 2Fineness by the 150-m (No. 100) and 75-m (No. 200) Sieves 3-5Fineness by the Turbidimeter 6 and 7Fineness by the 45-m (No. 325) Sieve 8Fineness by the Air Permeability Test 9Temperature and Relative Humidity, Storage Equipment 10-13Mixing Ce
16、ment Pastes and Mortars 14-24Normal Consistency 25-27Autoclave Expansion 28-32Time of Setting 33-36Strength Tests 37 and 38Tensile Strength 39-42Compressive Strength 43-45Flow Table 46Air Content of Mortar 47-51Standard Sand 52Calibration and Care of Apparatus 53Cement and Concrete Reference Laborat
17、ory 54Training of Cement Testers 55Cement Tests for Research Purposes 56Safety in the Cement Testing Laboratory 57Chemical Analysis of Hydraulic Cement 58SAMPLING(See Practice C 183)1,21. Treatment of Samples1.1 Test samples must be forwarded to the laboratorypromptly in airtight, moistureproof cont
18、ainers. Ordinary paperor cloth sacks must not be used. Poly(vinyl chloride) samplecontainers, upon occasion, have been found to affect the airentraining potential of a cement sample. The same problemmight be experienced with containers made from other plastics.These containers should be used with ca
19、ution. Each sampleshould be marked plainly and identified completely on theoutside of the body of the container as to source and date ofsampling. Do not mark the lids of containers, since the lids maybe readily interchanged and lead to confusion. Also, a completeidentification should be enclosed in
20、the container. As it isimportant to keep variable influences at a minimum, the sampleshould be kept in airtight, moisture-proof containers from thetime it is taken until it is tested or made into specimens.Reserve portions of samples should be likewise protected aslong as they are kept.1.2 The secti
21、on on Amount of Testing of Practice C 183prescribes the number of tests per lot for most properties. Aftera quality history has been established, testing may be carriedout at the reduced rate as long as no pairs of results produce anaverage in the critical range. The critical range is so definedthat
22、 when the average of a pair of tests is outside the range,there is a 95% probability that if a large number of sampleswere tested, fewer than 5% would fail the specification limit. Itis based on the average range of results of pairs of samplesaccumulated during the development of the quality history
23、.Where the specification limit is a minimum value, the criticallimit is placed above the specification limit by an amount equalto the average range multiplied by 2.49. The critical rangeincludes all possible test results with values below the criticallimit. Where the specification limit is a maximum
24、 value, thecritical limit is below the specification limit, and the criticalrange includes all results above the critical limit. The criticallimit is intended to ensure that the mean of the population oftest results is removed from the specification limit by at least1.645 standard deviations, that b
25、eing the value correspondingto a failure rate of 5 %. Since the standard deviation of asampling distribution of averages of pairs is equal to thepopulation standard deviation divided by the square root of 2,the critical limit, which is the 95% confidence limit, must beremoved from the desired positi
26、on mean by a distance equal to1.645/=2 or 1.163 standard deviation. Thus, the distancebetween the critical limit and specification limit must be thesum of 1.645 and 1.163, or 2.808 standard deviations. Since,for a sample size of 2 the standard deviation is exactly equal to0.886 range, the distance b
27、etween the critical limit and thespecification may be expressed as 2.49 average ranges.1.3 Chapter 8 of The American Concrete Institute docu-ment, Guide to Selection and Use of Hydraulic Cements, ACI225.1 R,3is a review of sampling and testing procedures ofhydraulic cement that are commonly found in
28、 the industry. Thevarious aspects of sampling, testing, and reporting of data arediscussed and may provide useful information on the severalquality control and acceptance procedures that are commonlyused.42. Preparation of Samples for Test2.1 Prior to testing, a sample shall be thoroughly mixed andp
29、assed through the 850-m (No. 20) sieve or any other sievehaving approximately 20 openings per inch, and brought toroom temperature. All foreign matter and lumps that do notbreakup on sieving and brushing easily must be discarded.2.2 Note any unusual conditions of the sample.2Annual Book of ASTM Stan
30、dards, Vol 04.01.3American Concrete Institute, P.O. Box 9094, Farmington Hills, MI 48333-9094.4For additional information see the paper by Dywer, J. R., and Young, R. N.,“Inspection of Portland Cement,” Concrete, Vol 21, August and September 1992, pp.56 and 95. This paper has been filed at ASTM Head
31、quarters and may be obtainedby requesting RR:C1-1002.MANUAL OF CEMENT TESTING2FINENESS BY THE 150-m(No. 100) AND THE 75-m (No. 200) SIEVES(See Test Method C 184)23. Accuracy of Sieve Tests3.1 The requirement for 150 m (No. 100) and 75 m (No.200) sieves has been deleted from the ASTM specification fo
32、rportland cement. These fineness tests may be useful forresearch or special purposes, such as raw material preparation.3.2 The operator must possess considerable skill, acquiredonly by practice in order to make satisfactory fineness deter-minations. With proper care, an experienced operator shouldch
33、eck himself within 1 %, and generally within 0.5 %, onportions of the same thoroughly mixed sample on the samesieve in duplicate tests. If an accuracy of 1 % or better isrequired, standard calibrated sieves shall be used.3.3 Remove the super fines from the sample before begin-ning the sieve test its
34、elf. This is most easily done by suspend-ing the sieve between the fingers of each hand and shaking itloosely back and forth, alternately striking the palms of thehands. Five to ten minutes of sifting will clean the sample veryadequately. Before beginning the 1-min shaking tests, it isimportant to s
35、ee that no flour has blinded any of the screenopenings. When performing the 1-min shaking test, eachoperator should experiment to determine the angle from thehorizontal at which the sieve is to be held. When the properangle has been reached, the residue distributes itself across thescreen during eac
36、h stroke so that most effective screeningaction is obtained. It is also important that the sieve is movedagainst the hand held in the upright position. Some operatorstake liberties with the test and strike the sieve with the palm ofthe open hand. Screening is not complete when this is done.The weigh
37、t of residue will tend to be high. The rate at whichthe sieve strikes the palm is important. Take a full 10 s for each25 strokes in each of the six positions. Do not try to do the 125strokes and the five rotations in 1 min. When this is done thestroke rate is speeded up and there is a tendency to st
38、rike thepalm less hard, which again tends toward high residues.4. Design of Sieves4.1 It is essential that all sieves used in the tests of finematerials be well designed and constructed and that they beprovided with closely fitting covers and pans in order to avoidthe loss of small quantities of mat
39、erial during the sievingoperation.5. Care of Sieves5.1 Sieves should be examined frequently for defects in thecloth. Holes or breaks are sometimes indicated by verynoticeable irregularities in the end-point test weighings. Holesare sometimes found in the soldered joint between the sieveand frame. So
40、ldering must be done with great care so that thewire cloth is not injured by excessive heat or by harmful fluxes.Sieves should be kept thoroughly clean and dry. The batteringof edges of sieve frames and pans should be avoided, for thiswill interfere with the proper fitting together of pan, sieve, an
41、dcover. The brush used for cleaning the sieve should be stiffenough to clean cloth, but not so heavy as to damage it. Becareful that the brush is not so held that the metal binding willdrag across the sieve cloth and press objectionable ridges in it.5.2 New sieves should be cleaned with a suitable s
42、olvent ordetergent to remove any grease before making tests. Alcoholmay attack the lacquer on some sieve frames.FINENESS BY THE TURBIDIMETER(See Test Method C 115)26. Difficulties6.1 Some operators have found it difficult to oscillate thetank the full 180 about a horizontal axis through the center o
43、fthe tank. Complete rotation is necessary for proper agitation. Adesign of a rotatable holder is available on request from theCement and Concrete Reference Laboratory at the NationalInstitute of Standards and Technology, Gaithersburg, MD20899.6.2 A previously opened standard fineness sample willbeco
44、me unsuitable for calibration purposes. Whenever anunexpected difficulty is encountered, a new sample should beopened.6.2.1 Opening a Standard Fineness SampleCare shouldbe taken when opening a new sample. The most recent finenessstandard, beginning with SRM 114P, is packaged in plasticbags, which gr
45、eatly simplifies opening the sample. Previousfineness standards were packaged in glass vials. When openinga sample packaged in a glass vial, contamination with glasschips shall be avoided. One satisfactory method of opening avial consists of inverting the vial and pressing the sides in theempty sect
46、ion against a thin curved high-resistance wiremounted across the terminals of a small transformer.6.3 The derivation of the Wagner equation is based on alight intensity (Io) of 100 microamperes (A). For someunexplained reasons, the light intensities arrived at by calibrat-ing with NIST SRM 114 have
47、shown a great increase withsome Ios being 150 or more. In addition to the calibrationbeing time consuming and laborious, test results are subject toincreasingly larger errors as the Iodeviates further from 100A.7. Care of Apparatus7.1 Great care must be taken to keep the various parts of theapparatu
48、s clean, and to maintain good electrical contacts. Thislast precaution especially relates to the electric bulb, rheostat,and the wire leads to the shelf. It is particularly important tokeep the water cell clean. At times the cell glasses will becomedirty. A wavy film of growth will sometimes develop
49、 in thecell, causing decided fluctuations in the intensity of thetransmitted light when the water is disturbed by the movementof the shelf. Keep the cell completely filled with distilled water.A drop or two of potassium dichromate solution added to thewater in the cell will serve to inhibit possible algae growth butwill not be enough to discolor the water.7.2 The tank support must be so adjusted that, when usingthe specified volume of suspension the top of the suspensionwill be at the level of the zero mark on the graduated scale ofthe turbidimeter case, and the tank will be in
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