The Effect of Corrosion on the Expansion of Concrete
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Date
2020-01-17
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Addis Ababa University
Abstract
Corrosion of reinforcement embedded in concrete is a major concern for the durability of
concrete. Its effect is seen through tensile strain development, loss of bond between
concrete and rebar or the reduction in the cross-sectional area of the reinforcement. The
corrosion products (solid and liquid portion) might exhibit more than six times as
compared to the parent rebar. Accordingly, this volumetric expansion of the products
causes hoop tensile stress on the concrete.
The research tried to investigate the effects of concrete quality, nature of rebar and the
clear cover thickness on the expansion experienced by concrete specimens when
reinforcements within them corrode.
A total of fifteen cylindrical concrete samples having a central reinforcement running
through them were prepared for three different water to cement ratios. Out of the fifteen
samples, six of them had 45mm clear cover while the rest had 28mm. The samples were
prepared to alleviate end effect using corrosion resistant epoxy.
To figure out a proper accelerated corrosion test (ACT) set-up, three trial corrosion tests
were carried out. Finally, a suitable test set-up was devised and the ACTs of the samples
were grouped into four and were performed.
After the analysis of the experimental outputs, it was found that as the water cement ratio
increases the strain due to corrosion increased for 28mm clear cover samples and the
contrary was the case for the samples with 45mm cover. Also, the clear cover thickness of
samples affected the strain development and this effect was seen to be massive for samples
with the highest water to cement ratio.
In addition, samples with plane bars showed a slight resilience against corrosion. However,
once corrosion started along the surface of plane bars, the strain development is rapid and
for the lowest water to cement ratio this was more pronounced.
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Keywords
Corrosion, Reinforcement, Expansion, Accelerated corrosion test