Structural Engineering

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Browsing Structural Engineering by Subject "Accelerated corrosion test"

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    The Effect of Corrosion on the Expansion of Concrete
    (Addis Ababa University, 2020-01-17) Ezekel, Zeleke; Esayas, Gebreyouhannes (PhD)
    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.