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ASTM C115 : Fineness of Portland Cement by the Turbidimeter

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Designation: C 115 – 96a

Standard Test Method for

Fineness of Portland Cement by the Turbidimeter1
This standard is issued under the fixed designation C 115; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.

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 measured 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 4.2-4.7 and shall be constructed in accordance
with the detailed design and dimensional requirements shown
in Fig. 1 and Table 1, except that the case may be either of
wood or of metal.
4.2 Turbidimeter, mounted in a suitable wood or metal case
including the following features:
4.2.1 Source of Light—The source of light (Fig. 1) shall
consist of a concentrated-filament electric lamp of between 3
and 6 cd operated by a source of constant emf. The lamp shall
be mounted rigidly in the socket. A clean, bright parabolic
metallic reflector shall be rigidly mounted behind the lamp,
focused so that approximately parallel rays of light will pass
through the sedimentation tank and impinge upon the photoelectric cell. The light intensity shall be regulated by two
rheostats of approximately 6 and 30 V, respectively, and they
shall possess such characteristics that uniform changes in light
intensity may be obtained over the full range of resistance. The
rheostats shall be mounted in parallel with each other and in
series with the lamp.
4.2.2 Heat-Absorbing Device—The light shall pass through
a suitable heat absorbing device before entering the sedimentation tank in order that radiant heat from the beam shall be
absorbed, the device being either (1) a water cell or (2) a
special heat-absorbing glass filter. The water cell shall be made
from 76-mm (3-in.) outside diameter seamless brass tubing,
3-mm (1⁄8-in.) thick wall, 102-mm (4 in.) in length with glass
windows sealed in the ends. The cell shall contain a hole fo...
Designation: C 115 – 96a
Standard Test Method for
Fineness of Portland Cement by the Turbidimeter
1
This standard is issued under the fixed designation C 115; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method covers determination of the fineness of
portland cement as represented by a calculated measure of
specific surface, expressed as square centimetres of total
surface area per gram, or square metres of total surface area per
kilogram, of cement, using the Wagner turbidimeter.
2
1.2 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
responsibility 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 the
standard. The inch-pound equivalents may be approximate.
2. Referenced Documents
2.1 ASTM Standards:
C 114 Test Methods for Chemical Analysis of Hydraulic
Cement
3
C 430 Test Method for Fineness of Hydraulic Cement by
the 45-µm (No. 325) Sieve
3
C 670 Practice for Preparing Precision and Bias Statements
for Test Methods for Construction Materials
4
3. Significance and Use
3.1 The purpose of this test method is to determine whether
or not the hydraulic cement under test meets the Wagner
turbidimetric fineness requirements of the applicable hydraulic
cement specification for which the test is being made. Fineness
of the cement component is only one of the many character-
istics that influence the strength capabilities of concrete.
4. Apparatus
4.1 Nature of Apparatus—The Wagner 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 measured 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 4.2-4.7 and shall be constructed in accordance
with the detailed design and dimensional requirements shown
in Fig. 1 and Table 1, except that the case may be either of
wood or of metal.
4.2 Turbidimeter, mounted in a suitable wood or metal case
including the following features:
4.2.1 Source of Light—The source of light (Fig. 1) shall
consist of a concentrated-filament electric lamp of between 3
and 6 cd operated by a source of constant emf. The lamp shall
be mounted rigidly in the socket. A clean, bright parabolic
metallic reflector shall be rigidly mounted behind the lamp,
focused so that approximately parallel rays of light will pass
through the sedimentation tank and impinge upon the photo-
electric cell. The light intensity shall be regulated by two
rheostats of approximately 6 and 30 V, respectively, and they
shall possess such characteristics that uniform changes in light
intensity may be obtained over the full range of resistance. The
rheostats shall be mounted in parallel with each other and in
series with the lamp.
4.2.2 Heat-Absorbing Device—The light shall pass through
a suitable heat absorbing device before entering the sedimen-
tation tank in order that radiant heat from the beam shall be
absorbed, the device being either (1) a water cell or (2)a
special heat-absorbing glass filter. The water cell shall be made
from 76-mm (3-in.) outside diameter seamless brass tubing,
3-mm (
1
8
-in.) thick wall, 102-mm (4 in.) in length with glass
windows sealed in the ends. The cell shall contain a hole for
filling with distilled water. The hole shall be sealed with a
metal plug. The cell, when mounted on the movable shelf, may
have the plug in either the top or bottom position. The
heat-absorbing device shall be so arranged that essentially all
rays of light entering the sedimentation tank shall first pass
through the heat-absorbing device.
4.2.3 Retarding Filter—A light-retarding glass or other
device shall be provided that will reduce the intensity of light
from that corresponding to 100 µA to a reading of 20 to 30 µA.
The light intensity shall be uniformly retarded over the entire
1
This test method is under the jurisdiction of ASTM Committee C-1 on Cement
and is the direct responsibility of Subcommittee C01.25 on Fineness.
Current edition approved Dec. 10, 1996. Published February 1997. Originally
published as C 115 – 34 T. Last previous edition C 115 – 96.
2
This turbidimeter was developed by L. A. Wagner, Research Associate of the
Cement Reference Laboratory, National Institute of Standards and Technology,
Washington, DC. A description of the apparatus and the original mathematical
derivations of formulas used are given in the paper: Wagner, L.A., “ARapid Method
for the Determination of the Specific Surface of Portland Cement,” Proceedings,
ASTM, ASTEA, Vol 33, Part II, 1933, p. 553.
3
Annual Book of ASTM Standards, Vol 04.01.
4
Annual Book of ASTM Standards, Vol 04.02.
1
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
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