Reinforced concrete represents a very successful synergistic combination
of materials not only mechanically but also chemically since concrete
is a perfect material providing ideal environment with high alkalinity
for the corrosion protection of steel reinforcement embedded in it
although this is only valid when the concrete is designed properly to
satisfy the covering purpose.
The main problem regarding with the deterioration of reinforced concrete
as a result of corrosion is not the reduced mechanical strength of
reinforcement but rather the products of corrosion creating stresses
within concrete that cannot be supported by the limited plastic
deformation capability of concrete material itself leading to cracking
and in extreme cases to structural breakdown followed by relatively
lower service life than that of initially designed.
“This therefore brings about the idea of creating concrete material
which will be resistant enough to endure considerable plastic
deformations, have control over cracking behavior and be durable against
several major durability issues including rebar corrosion” says Mustafa
Sahmaran, Professor of Civil Engineering and Director of Advanced
Cementitious Materials Research Laboratory in Gazi University, Ankara,
Turkey.
Engineered Cementitious Composites - ECC which are designed based on the
micro-mechanical design constraints were first proposed and invented by
Professor Victor C. Li from University of Michigan, Ann Arbor. What
separates ECC from traditional concrete material mostly being used in
many civil engineering applications in the field is its strain hardening
response under excessive tensile and shear loadings which is similar to
many ductile metals.
The strain hardening behavior of ECC is a direct outcome of the
formation of multiple microcracks having widths generally less than 100
micrometer threshold. “Although it seems unrealistic to produce a
concrete material that is completely crack-free, with the control over
cracking behavior many durability problems of reinforced concrete
structures can be confronted” says Gürkan Yildirim, research assistant
and Ph.D. candidate in Civil Engineering at Gazi University.
On the material basis, ECC already proved itself worthy in terms of
freeze-thaw resistance, sulfate resistance, alkali-silicate resistivity,
reinforcement corrosion and so on. However, compared to studies using
small scale specimens, there are relatively less number of research
papers aiming at the ECCs’ durability performance evaluation at large
scale. Along these lines, Dr. Sahmaran and his lab team carried out a
series of experiment to assess the effect of corrosion level on shear
behavior of reinforced ECC and compared with conventional concrete.
According to the experimental findings compared to conventional concrete
with similar strength grades, ECC beams exhibited significantly higher
strength, stiffness, and energy absorption capacity, along with superior
performance in terms of the restriction of damage caused by
reinforcement corrosion. These performances of reinforced ECC (R/ECC)
are expected to contribute substantially to improving infrastructure
sustainability by reducing the amount of repair and maintenance during
the service life of the infrastructure.
The research can be found in a paper titled “Effect of Corrosion on Shear Behavior of Reinforced Engineered Cementitious Composite Beams” published in the ACI Structural Journal.
For more information, contact:
Julie Webb Marketing Communications Specialist
248-848-3148
[email protected]
