shall conform to all the requirements in ASTM C 94/C 94M applicable to
central-mixed concrete.
3.2.9
Truck Mixers
**************************************************************************
NOTE: Delete this subparagraph if truck mixers have
been previously prohibited, otherwise retain. Use
bracketed item only for small jobs.
**************************************************************************
Truck mixers, the mixing of concrete therein, and concrete uniformity shall
conform to the requirements of ASTM C 94/C 94M. A truck mixer may be used
either for complete mixing (transit-mixed) or to finish the partial mixing
done in a stationary mixer (shrink-mixed). Each truck shall be equipped
with two counters from which it is possible to determine the number of
revolutions at mixing speed and the number of revolutions at agitating
speed. [Or, if approved in lieu of this, the number of revolutions shall
be marked on the batch tickets.] Water shall not be added at the placing
site unless specifically approved; and in no case shall it exceed the
specified w/c. Any such water shall be injected at the base of the mixer,
not at the discharge end.
3.3
CONCRETE PRODUCTION, SMALL PROJECTS
**************************************************************************
NOTE: Use this paragraph at the designer's option
in lieu of the previous paragraph CONCRETE
PRODUCTION and its subparagraphs, which must then be
deleted, but only when all the following conditions
exist:
(a) There are no particularly critical structural
items.
(b) There are no items of particularly critical
appearance.
(c) No concrete is required with a specified
compressive strength greater than 24.2 MPa (3500
psi).
(d) Not over 1150 cubic meters (1500 cubic yards) of
concrete are required.
Otherwise, use the above listed previous paragraph
and subparagraphs only. Do not specify both options.
**************************************************************************
Batch-type equipment shall be used for producing concrete. Ready-mixed
concrete shall be batched, mixed, and transported in accordance with ASTM C
94/C 94M, except as otherwise specified. Truck mixers, agitators, and
nonagitating transporting units shall comply with NRMCA TMMB 100.
Ready-mix plant equipment and facilities shall be certified in accordance
with NRMCA QC 3. Approved batch tickets shall be furnished for each load
of ready-mixed concrete. Site-mixed concrete shall be produced in
accordance with ACI 301, and plant shall conform to NRMCA CPMB 100. [In
lieu of batch-type equipment, concrete may be produced by volumetric
batching and continuous mixing, which shall conform to ASTM C 685/C 685M.]
SECTION 03300A
Page 38
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