AASHTO T 98M T 98-2012 Standard Method of Test for Fineness of Portland Cement by the Turbidimeter.pdf

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1、Standard Method of Test for Fineness of Portland Cement by the Turbidimeter AASHTO Designation: T 98M/T 98-12 (2016)1Release: Group 1 (April 2016) ASTM Designation: C115/C115M-101American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D

2、.C. 20001TS-3a T 98-1 AASHTO Standard Method of Test for Fineness of Portland Cement by the Turbidimeter AASHTO Designation: T 98M/T 98-12 (2016)1Release: Group 1 (April 2016) ASTM Designation: C115/C115M-101 1. SCOPE 1.1. This test method covers determination of the fineness of portland cement as r

3、epresented by a calculated measure of specific surface, expressed as square centimeters of total surface area per gram or square meters of total surface area per kilogram of cement, using the Wagner turbidimeter.21.2. The values stated in either SI units or inch-pound units are to be regarded separa

4、tely as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard. Values in SI units (or inch-pound units) shall be obtained by measur

5、ement in SI units (or inch-pound units) or by appropriate conversion, using the Rules for Conversion and Rounding given in IEEE/ASTM SI 10 of measurements made in other units. Values are stated in SI units when inch-pound units are not used in practice. 1.3. This standard does not purport to address

6、 all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: T 105, Chemi

7、cal Analysis of Hydraulic Cement T 192, Fineness of Hydraulic Cement by the 45-m (No. 325) Sieve 2.2. ASTM Standard: C670, Standard Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials 2.3. IEEE/ASTM Standard: SI 10, American National Standard for Metric P

8、ractice 3. SIGNIFICANCE AND USE 3.1. The purpose of this test method is to determine whether the hydraulic cement under test meets the Wagner turbidimetric fineness requirements of the applicable hydraulic cement specification for 2016 by the American Association of State Highway and Transportation

9、Officials.All rights reserved. Duplication is a violation of applicable law.TS-3a T 98-2 AASHTO which the test is being made. Fineness of the cement component is only one of the many characteristics that influence the strength capabilities of concrete. 4. APPARATUS 4.1. Nature of ApparatusThe Wagner

10、 turbidimeter consists essentially of a source of light maintained at constant intensity and adjusted so that approximately parallel rays of light pass through a suspension of the cement to be tested and impinge upon the sensitive plate of a photoelectric cell. The current generated in the cell is m

11、easured by means of a microammeter and the indicated reading is a measure of the turbidity of the suspension. General considerations indicate that turbidity is in turn a measure of the surface area of the suspended sample of cement. The apparatus shall consist specifically of the parts described in

12、Sections 4.2 through 4.7, and shall be constructed in accordance with the detailed design and dimensional requirements shown in Figure 1 and Table 1, except that the case may be either of wood or of metal. Table 1Turbidimeter Apparatus Dimensions (see Figure 1) Letter mm in. Letter mm in. A 445 171/

13、2T 51 2 B 438 171/4U 22.2 7/8C 381 15 V 34.9 13/8D 105 41/8W 13 1/2E 3.0 1/8X 38 11/2F 28.6 11/8Y 15.9 5/8G 85.7 33/8Z 38 0.76 1.5 0.03 H 33.3 15/16AA 51 2.5 2 0.10 I 102 4 AB 267 101/2 J 39.7 19/16AC 5/8aK 55.6 23/16AD 11aL 65.1 29/16AE 39.7 19/16M 28.6 11/8AF 55.6 23/16N 3.0 1/8AG 66.7 25/8O 51 2

14、AH 203 8 P 51 2 AI 23.6 0.93 Q 3.0 1/8AJ 1.38a31/2aR 61.1 213/32AK cmain.aS 69.8 23/4a These are pure numbers such as part of a thread designation and numbers of links per unit; consequently, they do not correspond with column titles. 2016 by the American Association of State Highway and Transportat

15、ion Officials.All rights reserved. Duplication is a violation of applicable law.Figure 1Dimensional Details of Turbidimeter Fineness Test Apparatus (see Table 1) 17.5 2.5cm38 4cm7 1cm1.9 2 cmInside DiaOpening inStem 0.090 0.005 cm200-mL FlaskFront ViewTiming BuretSide ViewWiring DiagramMicroammeter3

16、6 cp Lamp = viscosity of kerosene at the temperature of calibration, P; 1= density of cement particles, Mg/m3(g/cm3) = 3.15 for portland cement (see Note 4); 2= density of kerosene, Mg/m3at the temperature of calibration; h = depth of the suspension to level of light, cm; and d = diameter of particl

17、e, m. Values of h/d2are given in Table 2. 7.1.1.2. Fill the buret with kerosene at the calibrating temperature, start a timing clock at the instant the kerosene in the buret drains past the zero line, and mark on the buret the levels reached by the draining kerosene for each of the time intervals, t

18、, calculated as described above. At these marks, etch permanent lines and numbers on the buret indicating the corresponding diameters (see Note 5). The construction and the graduation of the buret shall be such that at the temperature of calibration the time required for the kerosene to pass the per

19、manent lines of the buret agrees with the calculated time of settling within 1 percent, except that the permissible variation shall be not less than 1 s. Note 4The density of portland cement does not vary greatly, and in this work, it is considered constant at 3.15. A variation of 0.15 from this val

20、ue when substituted in Stokes law gives a variation of 2.5 percent in the diameter of the particle measured. Note 5By using the calibrated buret, the apparatus may be used within the normal range of room temperatures without further correction, the change in rate of flow of the kerosene from the bur

21、et automatically compensating for change in viscosity of the suspension due to temperature. The temperature of the kerosene in the buret and that of the suspension should be kept the same within 0.5C (1F). This condition will ordinarily exist if the supply of kerosene is kept in the same room as the

22、 apparatus. Care must be taken to ascertain that only clean kerosene is used in the buret, and, in addition, the capillary should be examined frequently to make sure that no small pieces of lint or other foreign material have become lodged in it. 7.1.2. Calibration of 45-m (No. 325) SieveCalibration

23、 shall be made in accordance with T 192, basing the percentage sieve correction on the difference between the test residue obtained and the assigned residue value indicated by the electroformed sheet sieve fineness specified for the standard sample, expressed as a percentage of the test residue. 7.1

24、.3. Determination of the Proper Light Intensity, Ir: 7.1.3.1. Fill the sedimentation tank to the mark with clear kerosene. 7.1.3.2. For a turbidimeter equipped with a digital-type microammeter with a range of 199.9 A, place the sedimentation tank containing clear kerosene against the guides of the t

25、ank support in the turbidimeter. Set the light intensity so that the microammeter reads 100.0 A. Readjust the light intensity until equilibrium is established at this reading. Place the light-retarding filter in the path of the light beam. When equilibrium is established, record this meter reading a

26、s Ir. This meter reading becomes the reference value for the intensity of the light. Meter readings are also taken at the beginning and end of each test through the light-retarding filter alone to check the requirements of Section 8.3.8. 7.1.3.3. For a turbidimeter equipped with a DArsonval-type mic

27、roammeter, place the sedimentation tank containing clear kerosene against the guides of the turbidimeter. Set the light intensity so that the 2016 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-3a T 98-8

28、AASHTO microammeter reads 50.0 A with the light-retarding filter removed from the light path. Readjust the light intensity until equilibrium is established at this reading. Connect resistors or resistor combinations as indicated in Figure 2 so that the meter reading is reduced to an equilibrium valu

29、e between 23.0 and 25.0 A. Increase the light intensity until the equilibrium light reading obtained between 23.0 and 25.0 A is exactly doubled. Readjust the light intensity until the equilibrium is established at this doubled meter reading level. Place the light-retarding filter in the path of the

30、light beam. Remove the resistors from the meter circuit. When equilibrium is established, record this meter reading as Ir. This becomes the reference value for the intensity of the light. Adjust the rheostats at the beginning of each test to give this meter reading through the filter plus the tank o

31、f clear kerosene. This meter reading corresponds to a meter reading of 100.0 A through the tank containing clear kerosene with the light filter removed from the light path. Meter readings are also taken at the beginning and the end of each test through the light-retarding filter alone to check the r

32、equirements of Section 8.3.8. Figure 2Illustrated Example of DArsonval Meter Circuit for IrDetermination Note 6A 1/2-W carbon resistor, preferably with 5 percent tolerance limits, can be used to obtain the desired meter readings. The shunt resistor or resistor combination as shown in Figure 2 shall

33、have a resistance value between 85 and 100 percent of the value of the internal resistance of the meter as printed on the card in the meter cover. The series resistor shall have a resistance value equal to the difference between the internal resistance of the meter and the calculated resistance of t

34、he meter and shunt combination. Note 7A less exact, but still acceptable, procedure for determining a meter setting that corresponds to a current of 100.0 A through the meter with the light filter removed from the light path can be achieved by eliminating the series resistor in the meter circuit. Th

35、e internal resistance of the photocell is sufficiently large to cause only a minor error of approximately 0.5 percent in the desired setting when the series resistor is omitted from the circuit. SeriesResistanceResistanceShunt+PhotocellMicroammeterMicroammeter Internal Resistance = 90 Shunt Equivale

36、nt Resistance:470 in Parallel with 100 = = 82 Meter check that the rheostat contacts are clean; and make sure that the lamp, socket, and reflector are rigidly fixed in their mounting. 8.3.2. Determine the mass of the sample of cement in the appropriate amount and record the mass to the nearest 0.000

37、2 g. Prepare a suspension in accordance with Section 8.2. 8.3.3. Place the shelf-level pointer at the 3050-m position. 8.3.4. Fill the buret to the predetermined height with kerosene from the same lot and at the same temperature as the kerosene used in the suspension, and start oscillation of the ta

38、nk containing the suspension in accordance with Section 8.2.2. Continue the oscillation until the kerosene drains to the zero line on the buret, and then stop the agitation. Immediately place the tank in position in the path of the light beam. 8.3.5. Immediately remove the retarding filter from the

39、light path and close the cabinet door. 8.3.6. Read the microammeter to the nearest 0.1 A at the instant the kerosene in the buret drains past marks 50, 45, 40, 35, and 30. 8.3.7. Raise the shelf successively to the marks 25, 20, 15, 10, and 7.5 on the pointer scale, reading the microammeter at each

40、position as the kerosene drains past the corresponding mark on the buret. 8.3.8. Lower the shelf to the 3050-m position. Replace the filter in the path of the light beam, remove the tank, and check the intensity of the lamp. If the microammeter indication has shifted more than 0.3 A from the initial

41、 setting through the filter alone, the test must be repeated. 9. DATA RECORDING 9.1. The form shown in Table 4 is suggested for the recording of turbidimeter data and the calculation of specific surface. 2016 by the American Association of State Highway and Transportation Officials.All rights reserv

42、ed. Duplication is a violation of applicable law.TS-3a T 98-11 AASHTO Table 4Illustrative Form for Recording Turbidimeter Test Data and Calculation of Specific Surface (See Note 14.) Sample Identification Sample X Passing 45-m (No. 325) sieve, r, corrected, T 90.4 Calibration factor, K 33.9 Meter re

43、ading through filter alone, A: Before test 17.5 After test 17.5 Mass of sample tested, g 0.25 Particle Size, m I, A log I 50 17.3 1.238a45 17.4 1.241 40 17.6 1.246 35 17.9 1.253 30 18.4 1.265 25 19.1 1.281 20 20.1 1.303 15 21.6 1.334 10 23.9 1.378 7.5 25.6 1.408a0.75 1.408 1.506 1.500 Sum = 12.857 9

44、.5 1.238 11.761 Difference = 1.096 S = (33.9 90.4 0.762)/1.096 = 2131 cm2/g (Round to 2130 cm2/g or 213 m2/kg) a For convenience in calculation, log I50and log I7.5are rounded in a separate column. Note 14Values shown in Table 4 are for purpose of illustration only. 10. CALCULATION 10.1. Calculation

45、 of Specific Surface: 10.1.1. Calculate the turbidimeter specific surface as follows: 507 5 10 15 45 50(2 log )1 5 0 75log log log log 9 5log.rISK. . I I I . I . I=+ + +(2) where: S = specific surface of the sample, m2/kg; K = calibration factor as determined in Section 7.1.4; and r = corrected mass

46、 percent of sample passing the 45-m (No. 325) sieve (see Note 15), and I7.5, I10, I15, I50= microammeter readings, A, that correspond to the particle diameters 7.5, 10, 15, 50 m. Note 15The value of K as determined in Section 7.1.3 applies only to a material having the density of portland cement (ap

47、proximately 3.15 Mg/m3or g/cm3). For any other material, the corresponding value must be calculated for this factor, which, in the derivation of the formula, varies inversely as the density of the particles (g/cm3). 2016 by the American Association of State Highway and Transportation Officials.All r

48、ights reserved. Duplication is a violation of applicable law.TS-3a T 98-12 AASHTO 10.1.2. To calculate the specific surface values in square meters per kilogram, multiply the surface area in cm2/g by the factor of 0.1. 10.1.3. Round values in cm2/g to the nearest 10 units (in m2/kg to the nearest un

49、it). 10.2. Specific Surface from First Turbidity Reading I50This test method may be used or successive determinations from the same plant, provided that the same size test samples are used and that there is no great change in fineness, color, or other properties of the cement. Under these conditions the specific surface of a sample may be calculated from the first turbidity reading, I50, by using t