ETL 1110-2-343
31 May 93
RCC placing and compaction equipment in all areas
specifications. Project test sections should be con-
adjacent to the gallery. Since any interruption or
structed outside the footprint of all project features.
opening in the RCC lifts will reduce placement
Any test section placed during the design phase
rates, the location and method of gallery construc-
should be constructed by an experienced contractor
tion should be selected to minimize the extent to
hired especially to construct the test section. Con-
which RCC production is affected. The opening or
struction should be closely controlled by the design-
void created by the gallery may also contribute to
ers and the materials engineer, and extensive testing
stress concentrations and cracking and should be
should be performed. Tests on the unhardened,
considered in the design. Gallery construction
freshly mixed RCC should include: (1) vebe con-
details are shown in Figure 1-17 and gallery con-
sistency using the modified vebe apparatus shown
struction is shown in Figures 1-18 to 1-20. Typical
in EM 1110-2-2006 (Reference 12c), (2) determina-
gallery construction details are shown using (a)
tion of inplace density using a nuclear density
gravel/sand fill replacement, and (b) cast-in-place
meter, (3) moisture content, (4) air content, and
concrete methods. Gravel/sand is placed concur-
(5) fabrication of strength test specimens. Tests on
rently with RCC at the desired location of the gal-
the in situ samples retrieved from the hardened
lery. After placement of the RCC the gravel/sand
RCC may include permeability and compressive,
fill is excavated to form the completed gallery. The
tensile, shear, and flexural strength tests on samples
advantage of this method is that access for placing,
with and without lift joints. Each test section
spreading, and compacting equipment is not
should be sufficiently large to permit use of full-
restricted. Waterstops must be encased in a region
size production equipment (similar to the type antic-
of conventionally placed slump concrete in order to
ipated for use on the project) and to permit "shake-
achieve the desired seepage control. Similarly,
down" and subsequent steady operations to be
joints that require load transfer through dowel
attained. Funds expended on the test section are
action shear friction must be detailed so the dowels
nearly always returned many times over in in-
are encapsulated in conventional concrete. Water-
creased quality of production construction. All
stop details are shown in Figure 1-21 and
operations to be used in the RCC placement process
Figure 1-22 shows installation of a waterstop at a
should be included in the test fill construction in
contraction joint. The waterstop is placed in a zone
order to identify any potential problem areas. This
of conventional concrete facing at the upstream face
includes operations such as: forming for conven-
of a gravity dam at the location of the designed
tional concrete to be placed upstream and/or down-
contraction joint.
stream; bedding mortar placement; compaction of
downstream unformed faces; and the use of any
k. Test placements. A preliminary test place-
unusual equipment to deliver, spread or compact the
ment section should be completed during project
RCC.
design to confirm RCC mixture design characteris-
l. Reinforcement in RCC placements.
tics and to allow observation of placement and
compaction procedures. This will provide a means
of evaluating mixture proportions, aggregate charac-
(1) Anchorage reinforcement. It becomes nec-
teristics, time intervals between lift placements, lift
essary at times to embed reinforcing steel in the
thickness, placement and compaction techniques,
RCC for the purpose of anchoring various structural
RCC temperature gain characteristics, and lift joint
features and appendages. These structural features
treatment. For smaller projects it may be more
could be intakes for outlet work, training walls for
practical to construct such a test section early in the
spillways, parapets, etc. The anchorage of these
life of the contract. For any major project, con-
features to the RCC structure can either be accom-
struction of a test section by the project contractor
plished by installing the rebar during RCC place-
is essential even if a "preliminary" test section was
ment, or by drilling and grouting the rebar in place
completed during the design phase. The "project"
following RCC placement.
test section will provide an opportunity for a con-
tractor to develop and confirm techniques and
Although it is common practice to install anchorage
equipment for efficient placement of the RCC. A
reinforcement during RCC placement, this practice
project test section should also be used to demon-
has some disadvantages. First, it is difficult to
strate the contractor's capability to produce the
position the rebar so that it meets location
quality and quantity of RCC required by contract
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