ASTM C115-1996a(2003) Standard Test Method for Fineness of Portland Cement by the Turbidimeter《用浊度计测定硅酸盐水泥细度的标准试验方法》.pdf

1、Designation: C 115 96a (Reapproved 2003)Standard Test Method forFineness of Portland Cement by the Turbidimeter1This standard is issued under the fixed designation C 115; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of

2、last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers determination of the fineness ofportland cement as represented by a calculated measure ofspec

3、ific surface, expressed as square centimetres of totalsurface area per gram, or square metres of total surface area perkilogram, of cement, using the Wagner turbidimeter.21.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility

4、 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.1.3 The values stated in SI units are to regarded as thestandard. The inch-pound equivalents may be approximate.2. Referenced Documents2.1 ASTM

5、Standards:C 114 Test Methods for Chemical Analysis of HydraulicCement3C 430 Test Method for Fineness of Hydraulic Cement bythe 45-m (No. 325) Sieve3C 670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction Materials43. Significance and Use3.1 The purpose of this tes

6、t method is to determine whetheror not the hydraulic cement under test meets the Wagnerturbidimetric fineness requirements of the applicable hydrauliccement specification for which the test is being made. Finenessof the cement component is only one of the many character-istics that influence the str

7、ength capabilities of concrete.4. Apparatus4.1 Nature of ApparatusThe Wagner turbidimeter consistsessentially of a source of light maintained at constant intensityand adjusted so that approximately parallel rays of light passthrough a suspension of the cement to be tested and impingeupon the sensiti

8、ve plate of a photoelectric cell. The currentgenerated in the cell is measured by means of a microammeterand the indicated reading is a measure of the turbidity of thesuspension. General considerations indicate that turbidity is inturn a measure of the surface area of the suspended sample ofcement.

9、The apparatus shall consist specifically of the partsdescribed in 4.2-4.7 and shall be constructed in accordancewith the detailed design and dimensional requirements shownin Fig. 1 and Table 1, except that the case may be either ofwood or of metal.4.2 Turbidimeter, mounted in a suitable wood or meta

10、l caseincluding the following features:4.2.1 Source of LightThe source of light (Fig. 1) shallconsist of a concentrated-filament electric lamp of between 3and 6 cd operated by a source of constant emf. The lamp shallbe mounted rigidly in the socket. A clean, bright parabolicmetallic reflector shall

11、be rigidly mounted behind the lamp,focused so that approximately parallel rays of light will passthrough the sedimentation tank and impinge upon the photo-electric cell. The light intensity shall be regulated by tworheostats of approximately 6 and 30 V, respectively, and theyshall possess such chara

12、cteristics that uniform changes in lightintensity may be obtained over the full range of resistance. Therheostats shall be mounted in parallel with each other and inseries with the lamp.4.2.2 Heat-Absorbing DeviceThe light shall pass througha suitable heat absorbing device before entering the sedime

13、n-tation tank in order that radiant heat from the beam shall beabsorbed, the device being either (1) a water cell or (2)aspecial heat-absorbing glass filter. The water cell shall be madefrom 76-mm (3-in.) outside diameter seamless brass tubing,3-mm (18-in.) thick wall, 102-mm (4 in.) in length with

14、glasswindows sealed in the ends. The cell shall contain a hole forfilling with distilled water. The hole shall be sealed with ametal plug. The cell, when mounted on the movable shelf, mayhave the plug in either the top or bottom position. Theheat-absorbing device shall be so arranged that essentiall

15、y all1This test method is under the jurisdiction of ASTM Committee C01 on Cementand is the direct responsibility of Subcommittee C01.25 on Fineness.Current edition approved July 10, 2003. Published September 2003. Originallyapproved in 1934. Last previous edition approved in 1996 as C 115 96a.2This

16、turbidimeter was developed by L. A. Wagner, Research Associate of theCement Reference Laboratory, National Institute of Standards and Technology,Washington, DC. A description of the apparatus and the original mathematicalderivations of formulas used are given in the paper: Wagner, L. A., “A Rapid Me

17、thodfor the Determination of the Specific Surface of Portland Cement,” Proceedings,ASTM, ASTEA, Vol 33, Part II, 1933, p. 553.3Annual Book of ASTM Standards, Vol 04.01.4Annual Book of ASTM Standards, Vol 04.02.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 1

18、9428-2959, United States.rays of light entering the sedimentation tank shall first passthrough the heat-absorbing device.4.2.3 Retarding FilterA light-retarding glass or otherdevice shall be provided that will reduce the intensity of lightfrom that corresponding to 100 A to a reading of 20 to 30 A.T

19、he light intensity shall be uniformly retarded over the entirearea of that portion of the cell which is exposed to light duringa test. The retarding filter shall be mounted in a carrier on theshield and shall be capable of being swung out of the light pathby means of a handle.4.2.4 Sedimentation Tan

20、kThe sedimentation tank shall beeither (1) constructed of 5 to 6-mm (316 to14-in.) plate glass orborosilicate glass cemented or sealed together to form arectangular tank, or (2) a molded glass tank having wallsapproximately 5-mm (316 in.) thick with plane surfaces. Theinside dimensions of the rectan

21、gular tank shall be 51 mm by 38mm by 203 mm (2 in. by 112 in. by 8 in.) in height. Thepermissible variation on the inside dimensions of the tank shallbe 62.5 mm (0.1 in.) in length and 60.76 mm (0.03 in.) inwidth. The 51-mm faces of the tank shall be equidistant within0.25 mm (0.1 in.) at all points

22、. A mark shall be placed on theside of the tank to indicate a volumetric content of 335 mL,which is the level to which the tank will be filled in a test. Atank filled to the mark with clear kerosine and placed in theturbidimeter light beam shall yield uniform microammeterreadings, within 60.1 A, for

23、 the entire usable portion of thetank.4.2.5 Photoelectric CellThe means of measuring the lightintensity shall be a sensitive photoelectric cell5connecteddirectly to a microammeter. A hood with a horizontal slot 13mm (12 in.) in height by 35 mm (138 in.) in width shall bemounted over the photoelectri

24、c cell. The front of the hood shallbe 25 6 1mm(16116 in.) in front of the face of the cell. Theface of the photocell shall be parallel to the tank faces within0.5 mm (0.02 in.).4.2.6 ShieldA metallic shield having a slot 16 mm (58 in.)in height by 38 mm (112 in.) in width, as indicated in Fig. 1,sha

25、ll be placed between the heat absorbing device and thesedimentation tank.4.2.7 Elevating DeviceThe source of the light, the heat-absorbing device, the photoelectric cell, the retarding filter, andthe shield shall be mounted on a movable shelf which may beraised or lowered by two connected lead screw

26、s, and whichmay be readily and accurately adjusted so that the turbidity ofthe suspension may be determined at any desired depth. Thecenter of the light source, the heat absorbing device, thephotocell, the center of the slots of the metal shield, and thehood shall be on a straight line which is para

27、llel to the shelf.The sedimentation tank shall be mounted on a base which isindependent of the rest of the apparatus so that the tank shall befree from vibration caused by moving the shelf. Care shall betaken that the shelf shall be level at all points of elevation andthat the tank shall be normal t

28、o the shelf. The distance betweenthe tank and the edges of the opening in the shelf shall vary notmore than164 in. (0.4 mm) between the “3050” and “0”positions. The level of the light beam with reference to thesurface of the suspension shall be indicated by a pointer whichwill travel along a scale m

29、ounted on the cabinet. The zero ofthe scale shall indicate that position at which the center lines ofthe slots for the light beam are at the same elevation as thesurface of the liquid in the tank when filled to the 335-mLlevel. The lines on the scale to be marked 7.5, 10, 15, 20, 25,and 3050, shall

30、be located at distances from the zero markequal to suspension depth values, h, in Table 2. The scale, whencompared with a standard scale accurate to within 0.1 mm at allpoints, shall not show a deviation at any point greater than 0.25mm and shall indicate the positions at which the pointer shouldbe

31、located when turbidity readings for these values of h aretaken. The interior of the turbidimeter cabinet and the exteriorsurfaces of the shelf, the parabolic reflector, the heat absorbingdevice, the shield, and the photoelectric cell hood shall bepainted with a dull flat black paint.NOTE 1The requir

32、ement of the 0 to 50 markings on the scale shallapply only to new Wagner Turbidimeters and not to equipment in usewhich meets the other requirements of this method.4.3 Microammeters:4.3.1 DArsonval-Type Microammeters shall have a rangefrom 0 to 50 A and shall be readable to 0.1 A. Newmicroammeters s

33、hall be accurate to 60.5 % of full scale valueat any part of the scale value at any part of the scale at 77F(25C). For microammeters, in use, the accuracy shall be thesame as for new instruments except that the accuracy at 40 and50 A shall be 61 % of full scale. The internal resistance of themicroam

34、meter shall be between 50 and 150 V . The microam-meter shall not be mounted upon a working surface containingor consisting of iron or steel, or near other magnetic influence.4.3.2 Digital Microammeter:NOTE 2A meter with a range of 199.9 A is satisfactory for use andenables the operator to read the

35、theoretical I0directly without supplemen-tary devices. The high internal resistance of the digital microammeter doesnot affect the linearity of readings at the light intensity levels encounteredin a Wagner turbidimetric determination of fineness.4.4 Source of CurrentA 6-V automobile starting andligh

36、ting storage battery or a source of constant emf shall beused for supplying current to the lamp.4.5 SieveThe sieve shall conform to the requirements ofTest Method C 430.5Weston Photronic type, Model 594YY is acceptable.Microammeter Internal Resistance = 90 VShunt Equivalent Resistance:470 V in paral

37、lel with 100 V5470 3 100470 1 1005 82 VMeter consequently, they do not correspond with the column titles.C 115 96a (2003)3upper end of the large tube shall be flared to serve as a funnelfor introducing kerosine into the tube. The buret shall conformto the limiting dimensions given in Table 3. The gr

38、aduationlines on the buret shall be complete circles. A filter made of No.325 (45-m) wire cloth shall be used with the timing buret anda cover shall be placed over the top of the buret when it is notin use.4.8 Weights and Weighing Devices, shall conform to therequirements of Methods C 114.5. Materia

39、ls5.1 Suspending LiquidClear white kerosine shall be usedwith the turbidimeter apparatus. The kerosine shall not bereused.6. Test Specimen or Sample6.1 Size of Test SampleSelect the size of the sample ofcement for test so that the initial microammeter reading isbetween 12 and 20 A.NOTE 3The followin

40、g approximations will be helpful in many in-stances in selecting the size of sample: 0.25 g for normal fineness cementsand 0.20 g for high fineness cements.7. Calibration7.1 Calibration of TurbidimeterCalibrate the turbidimeterapparatus in accordance with the following procedure:7.1.1 Calibration of

41、 Buret Scale:7.1.1.1 For calibration of the buret scale use a kerosinehaving a known viscosity and density for the temperature atwhich the calibration is to be made. Density and viscosity ofthe kerosine should be determined. Calculate the times of flowfrom the buret that correspond to the times of s

42、ettling for thedifferent sized particles, from the following equation:t 5 1,837,000h/r12r2!# 3 h/d2! (1)where:t = time of settling, or time of flow, s,h = viscosity of kerosine at the temperature of calibra-tion, P,r1= density of cement particles, Mg/m3(g/cm3) = 3.15 forportland cement (Note 4),r2=

43、density of kerosine, Mg/m3at the temperature ofcalibration,h = depth of suspension to level of light, cm, andd = diameter of particle, m.Values of h/d2are given in Table 2.7.1.1.2 Fill the buret with kerosine at the calibrating tem-perature, start a timing clock at the instant the kerosine in thebur

44、et drains past the zero line, and mark on the buret the levelsreached by the draining kerosine for each of the time intervals,t, calculated as described above. At these marks, etch perma-nent lines and numbers on the buret indicating the correspond-ing diameters (Note 5). The construction and the gr

45、aduation ofthe buret shall be such that at the temperature of calibration thetime required for the kerosine to pass the permanent lines of theburet agrees with the calculated time of settling within 1percent, except that the permissible variation shall be not lessthan 1 s.NOTE 4The density of portla

46、nd cement does not vary greatly and inthis work it is considered constant at 3.15. A variation of 0.15 from thisvalue when substituted in Stokes law gives a variation of 2.5 % in thediameter of the particle measured.NOTE 5By using the calibrated buret the apparatus may be usedwithin the normal range

47、 of room temperatures without further correction,the change in rate of flow of the kerosine from the buret automaticallycompensating for change in viscosity of the suspension due to tempera-ture. The temperature of the kerosine in the buret and that of thesuspension should be kept the same within 0.

48、5C (1F). This conditionwill ordinarily exist if the supply of kerosine is kept in the same room asthe apparatus.Care must be taken to ascertain that only clean kerosine is used in theburet, and, in addition, the capillary should be examined frequently tomake sure that no small pieces of lint or othe

49、r foreign material havebecome lodged in it.7.1.2 Calibration of No. 325 (45-m) SieveCalibrationshall be made in accordance with Method C 430, basing thepercentage sieve correction on the difference between the testresidue obtained and the assigned residue value indicated bythe electroformed sheet sieve fineness specified for the stan-dard sample, expressed as a percentage of the test residue.7.1.3 Determination of the Proper Light Intensity, Ir:7.1.3.1 Fill the sedimentation tank to the mark with clearkerosine.7.1.3.2 For a turbidime