ETL 1110-2-343
31 May 93
Conference dated 10 June 1981), and flexural
strength (ASTM C78).
g. Direct shear strength, bond, angle of inter-
joints may be determined using laboratory-cast
cylinders, laboratory-cast blocks or panels, or sawn
blocks and drilled cores removed from the RCC
structure. The tests are made following procedures
described in the U.S. Army Corps of Engineers
Rock Testing Handbook (RTH), Method RTH 203-
80, "Direct Shear Strength of Rock Core Speci-
mens." Tests are normally performed using various
confining pressures, and typical test programs will
include the determination of cohesion (shear
strength at zero confining load) and the angle of
internal friction. With the use of appropriate dial
gages, residual sliding shear strength may also be
determined.
h. Post-construction evaluation. A post-
construction drilling and testing program should be
conducted on all major hydraulic structures to con-
firm that the as-built properties of the RCC are in
conformance with the design requirements. Drilling
of the completed structure should be scheduled a
Figure 1-24.
Field core extracted from in-place
sufficient time after RCC placement as required to
RCC
assure adequate core recovery, but should be con-
ducted within 1 year of completion.
Cylinders are cured and capped using the same
Drilling should penetrate the full height of the struc-
procedures as for conventionally placed concrete.
ture at a sufficient number of locations to ensure a
f. Tensile strength. Direct tensile strength tests
statistically adequate sampling of the structure.
Testing should be conducted on the recovered cores
are made on cylinders, cores, or blocks using proce-
to confirm that: (a) lift joints meet structural
dures outlined in ASTM D2936, "Direct Tensile
requirements for shear and tensile strength, (b) the
Strength of Intact Rock Core Specimens." Speci-
RCC has the required compressive strength, and (c)
mens are cemented to steel end plates using high-
full uniform compaction has been achieved without
strength epoxy and moisture conditioned prior to
segregation. If an upstream zone of conventional
testing. Specimens with lift joints are tested with
concrete has been used, a majority of the core sam-
the lift joint centered within the middle third of the
ples should be taken far enough downstream to
tensile strength specimens. After testing, specimens
avoid intersecting the contact between RCC and the
are examined for type and location of failure,
conventional concrete. The results of the drilling
degree of bonded mortar, and aggregate failure.
and testing should be reported in the Post-Construc-
Since tensile strength is normally only between 5
tion Structural Report required by Section 9.d.
and 10 percent of the concrete compressive
strength, it is important that sufficient tests be made
8. Preliminary Structural Analysis Strength,
to ensure representative results. Other more indirect
Elastic and Thermal Properties
tests may also be made to determine or correlate
with tensile strength. These include: the tensile
a. General. Properties important to prelim-
splitting strength test (ASTM C496), the point load
inary structural investigations include compressive
tensile strength test (proposed method depicted in
strength, tensile strength, shear strength, modulus of
Proceedings of the International Construction Indus-
elasticity, Poisson's ratio, adiabatic heat rise and
try Research and Information Association
1-19
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