3.4
LIGHTWEIGHT AGGREGATE CONCRETE
In addition to the requirements specified for normal weight concrete,
lightweight aggregate concrete shall conform to the following. The
batching and mixing cycle shall be as directed based on written
recommendations from the aggregate supplier which the Contractor shall
furnish. Unless otherwise directed, the mixer shall be charged with
approximately 2/3 of the total mixing water and all of the aggregate. This
shall be mixed for at least 1.5 minutes in a stationary mixer or 15
revolutions at mixing speed in a truck mixer. The remaining ingredients
shall then be added and mixing continued as specified for normal weight
concrete. Lightweight aggregate concrete shall not be vibrated to the
extent that large particles of aggregate float to the surface. During
finishing, lightweight aggregate concrete shall not be worked to the extent
that mortar is driven down and lightweight coarse aggregate appears at the
surface. Lightweight aggregate concrete to be pumped shall have a cement
content of at least 335 kg/cubic meter 564 lb/cu. yd [A field trial run of
lightweight aggregate concrete placement and finishing shall be made in
accordance with ACI 213R.]
3.5
FIBER REINFORCED CONCRETE
**************************************************************************
NOTE: Only use fiber reinforcing when approved by
the structural designer. Drawings should indicate
where fiber reinforced concrete is located. Fiber
reinforcing is used (1) to help control cracking due
to drying shrinkage and thermal expansion and
contraction, (2) to reduce permeability, (3) to
increase impact capability, shatter resistance,
abrasion resistance, and toughness. Fiber
reinforcing will not: control cracking due to
structural stresses, significantly increase
strength, control curling or creeping, justify
reducing structural members, eliminate control
joints, or replace any moment or structural steel
reinforcement. Include flexural toughness tests
when synthetic reinforcement fibers are used to
increase toughness and when justified by size and
importance of job, but not when fibers are used only
to control shrinkage cracking. Include technical
representative when warranted by size and importance
of job.
**************************************************************************
Fiber reinforced concrete shall conform to ASTM C 1116 and as follows,
using the fibers specified in PART 2. A minimum of 0.9 kg of fibers per
cubic m 1.5 pounds of fibers per cubic yard of concrete shall be used.
Fibers shall be added at the batch plant. [Toughness indices shall meet
requirements for performance level I of ASTM C 1116.] The services of a
qualified technical representative shall be provided to instruct the
concrete supplier in proper batching and mixing of materials to be provided.
3.6
TRANSPORTING CONCRETE TO PROJECT SITE
Concrete shall be transported to the placing site in [truck mixers,]
[agitators,] [nonagitating transporting equipment conforming to NRMCA TMMB
100] or by approved [pumping equipment] [conveyors]. Nonagitating
SECTION 03300A
Page 39
Previous Page
