ETL 1110-2-343
31 May 93
consolidated by either tamping (for drier mixes) or
more commonly, by vibration. The vibration method
requires the use of a vibrating table, miscellaneous
surcharge tools, and molds meeting standard Ameri-
can Society for Testing Materials (ASTM) require-
ments. Standard plastic, paper, or tin molds may be
used for either method of consolidation but will
require some type of exterior confinement, such as
a close-fitting steel sleeve to withstand the heavy
impact loads if consolidated by tamping. Currently,
research is continuing for developing standard pro-
cedures for preparing and testing RCC specimens.
Figure 1-22. Installation of a waterstop at a
c. Retrieval of in situ samples. RCC may be
contraction joint
cored or sawn in the same manner as conventional
concrete. In order to reduce damage or failure at
lift joints, core barrels should be of the inner tube
or split-sleeve type that support the RCC core dur-
ing drilling. It may be several months before the
strength gain in mass RCC is sufficient to obtain
intact samples by coring or sawing. The success of
retrieval will be primarily dependent on the type
and condition of the drilling equipment, and the
experience of the drill crews. Field cores extracted
from in-place RCC are shown in Figure 1-24. Evi-
dence of "good" and "poor" consolidation is visually
apparent. Cores are often tested to confirm com-
pressive strength of the parent RCC and shear,
bond, and tensile strength of the lift joint surfaces.
Figure 1-23. Reinforced RCC. Heavy welded
wire mats can be placed in RCC to resist
d. Specimen size and curing. All RCC labo-
cracking and increase resistance to tensile
ratory cast and in situ specimens should meet the
stresses
minimum size and dimensional requirements as
specified in the ASTM testing standards for conven-
obtain the material properties important to structural
tional concrete. In general, cylinders, cores, beams,
analysis and thermal studies, and to validate
and blocks will preferably have a minimum dimen-
in-place concrete strengths of both the parent con-
sion of at least three times the nominal maximum
crete and RCC lift joints. Information is provided
size of coarse aggregate in the concrete. All RCC
in the following paragraphs on sampling, tests, and
laboratory cast specimens should be moist-cured
testing procedures used for RCC concrete. The
and in situ specimens should be moisture condi-
structural engineer and the laboratory materials
tioned the same as conventional concrete specimens.
engineers should work closely together to establish
e. Compressive strength. Compressive
a laboratory testing program that meets structural
needs. The structural engineer should become
strength tests are normally made on laboratory cast
familiar with the testing program and understand
6- by 12-in. cylinders or on drilled cores following
how testing procedures and specimen size can affect
standard ASTM testing procedures. Test results
results.
from laboratory cast specimens are analyzed, and
mixture proportions are adjusted, to obtain the
b. Fabrication of laboratory and field RCC
desired strength and workability. During construc-
specimens. Fabrication of RCC strength specimens
tion, RCC is sampled and compressive strength
requires some special equipment for compacting and
cylinders are cast at a frequency and at test ages
consolidating the "stiffer" RCC mixtures into speci-
defined by EM 1110-2-2000 (Reference 12b).
men molds or forms. Specimens may be
1-18
Previous Page
