In
terms of the hardened
properties, at similar water/cementitious material ratio, properly
proportioned, produced and placed SCC
is generally denser and less variable
than the equivalent conventional vibrated concrete, thereby resulting
in
improved strength and durability performance.
In
addition, compared to
conventional vibrated concrete, SCC at similar
water/cementitious material
ratio is expected to have:
•
The
same structural performance.
•
Equal or higher compressive and tensile strength
•
Equal to or lower shrinkage.
•
Equal to or better bond to the steel reinforcement
• Lower surface
absorption and therefore better durability.
These
properties are discussed below:-
Compressive
Strength: SCC
compressive strengths are comparable to those of conventional vibrated
concrete
made with similar mix proportions and water/cement ratio. There is no
difficulty in producing SCC with compressive strengths up to 60MPa.
Tensile
Strength: Tensile
strengths are based on the indirect splitting test on cylinders. For
SCC, the
tensile strengths and the ratios of tensile and compressive strengths
are in
the same order of magnitude as the conventional vibrated concrete.
Bond
Strength: Pull-out
tests have been performed to determine the strength of the bond between
concrete and reinforcement of different diameters. In general, the SCC
bond
strengths expressed in terms of the compressive strengths are higher
than those
of conventional concrete.
Modulus
of Elasticity: SCC
and conventional concrete bear a similar relationship between modulus
of
elasticity and compressive strength expressed in the form E/(fc)0.5,
where E =
modulus of elasticity, fc = compressive strength. This is similar to
the one
recommended by ACI for conventional normal weight concrete.
Long-term
performance of SCC mixes, such as durability and creep, are unknown at
present
due to the lack of long-term performance studies. The
higher sand content of
some of the mixes may lead to greater shrinkage values; however,
testing to
date shows that most SCC mixes exhibit similar shrinkage values to that
of
normal concrete.
