ASTM C305-99
(Practice)Standard Practice for Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency
Standard Practice for Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency
SCOPE
1.1 This practice covers the mechanical mixing of hydraulic cement pastes and mortars of plastic consistency.
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 appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: C 305 – 99 American Association State
Highway and Transportation Officials Standard
AMERICAN SOCIETY FOR TESTING AND MATERIALS
AASHTO No.: T162
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Practice for
Mechanical Mixing of Hydraulic Cement Pastes and Mortars
of Plastic Consistency
This standard is issued under the fixed designation C 305; 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.
NOTE 1—When the bracket is in the proper position beneath the motor
1. Scope
housing, the lugs are to the front and facing upward and the heads of the
1.1 This practice covers the mechanical mixing of hydraulic
adjustment screws are to the rear and facing downward in the path of the
cement pastes and mortars of plastic consistency.
sliding frame that holds the bowl. It is intended that the bracket be
1.2 This standard does not purport to address all of the
fastened at the front housing connection by inserting replacement screws
safety concerns, if any, associated with its use. It is the on an appropriate size upward through the opening in each lug and into the
existing threaded holes in the bottom of the motor housing. The original
responsibility of the user of this standard to establish appro-
stops for the sliding frame are to be filed down if they prevent the frame
priate safety and health practices and determine the applica-
from coming in contact with the adjustment screws.
bility of regulatory limitations prior to use.
NOTE 2—This is the approximate diameter of a grain of 20-30 sand as
described in Specification C 778.
2. Referenced Documents
4.2 Paddle—The paddle shall be readily removable, made
2.1 ASTM Standards:
2 of stainless steel, and shall conform to the basic design shown
C 778 Specification for Standard Sand
in Fig. 2. The dimensions of the paddle shall be such that
3. Significance and Use when in the mixing position the paddle outline conforms to the
contour of the bowl used with the mixer, and the clearance
3.1 This practice is intended for use in the mechanical
between corresponding points on the edge of the paddle and the
mixing of pastes and mortars for the testing of hydraulic
side of the bowl in the position of closest approach shall be
cements.
approximately 4.0 mm but not less than 0.8 mm.
4. Apparatus
4.3 Mixing Bowl—The removable mixing bowl shall have a
nominal capacity of 4.73 L, shall be of the general shape and
4.1 Mixer—The mixer shall be an electrically driven me-
comply with the limiting dimensions shown in Fig. 3, and
chanical mixer of the epicyclic type, which imparts both a
shall be made of stainless steel. The bowl shall be so equipped
planetary and a revolving motion to the mixer paddle. The
that it will be positively held in the mixing apparatus in a fixed
mixer shall have a minimum of two speeds, controlled by
position during the mixing procedure. There shall be provided
definite mechanical means. (Rheostat adjustment of speed will
a lid, made of a nonabsorbing material not attacked by the
not be acceptable.) The first, or slow speed shall revolve the
cement.
paddle at a rate of 140 6 5 r/min, with a planetary motion of
4.4 Scraper—The scraper shall consist of a semirigid rubber
approximately 62 r/min. The second speed shall revolve the
blade attached to a handle about 150 mm long. The blade shall
paddle at a rate of 285 6 10 r/min, with a planetary motion of
be about 75 mm long, 50 mm wide, and tapered to a thin edge
approximately 125 r/min. The electric motor shall be at least
1 about 2 mm thick.
124W( ⁄6hp). The mixer shall be equipped with either an
adjustment screw which is an integral part of the mixer or a
NOTE 3—A kitchen tool known as a plate and bowl scraper conforms to
clearance adjustment bracket such as the one shown in Fig. 1
these requirements.
(Note 1) to provide clearance between the lower end of the
4.5 Supplementary Apparatus—The balances, weights,
paddle and the bottom of the bowl that is not greater than 2.5
glass graduates, and any other supplementary apparatus used in
mm but not less than 0.8 mm (Note 2) when the bowl is in the
measuring and preparing the mortar materials prior to mixing
mixing position.
shall conform to the respective requirements for such apparatus
as specified in the method for the particular test for which the
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