Abstract :
The specific fracture energy of damconcrete
is a basic material characteristic needed for
the prediction of concrete dam behavior. Data on
fracture properties of dam concrete are quite limited
to date. A series of tests was carried out based
on the size effect due to a number of geometrically
similar notched specimens of various sizes. Experimental
tests include three-point bending tests. The
specimens were of square cross section with a span
to depth ratio of 2/5. Three different specimens
with depth of 200, 400 and 800mm were considered
for the purpose of testing. Concrete mixtures
are provided from the Caroon 3 dam project site
using river gravel or commonly crushed stones
from quarries. To compare the fracture properties
of dam concrete with normal concrete five types of
concrete mixes of 65, 50, 40, 30 and 20mm maximumaggregate
sizewere considered. For all mixes,
value of relative notch depth of 0.2 is used. Experimental
results show that aggregate size has an
important effect on specific fracture energy values
of dam concrete. According to specific fracture
energy definition based on size effect, the specific
fracture energy of concrete mixes of 65, 50, 4030 and 20mm M.S.A. are 178, 129, 88, 79 and
72 N/m, respectively. This indicates that the high
specific fracture energy of dam concrete is the
result of the nature, size and properties of its aggregate.
The difference between specific fracture
energy of normal and dam concrete should be
noticed in nonlinear analysis of concrete dams.
