Inhibition effect of Vernonia amygdalina extract on the corrosion of mild steel reinforcement in concrete in 0.2 M H2SO4 Environment
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Taylor & Francis
Abstract
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Inhibition effect of Vernonia amygdalina (bitter leaf) extract on the corrosion
behaviour of embedded mild steel rebar in concrete immersed in 0.2% H2SO4
solution was investigated by potential measurement, pH and gravimetric methods
using the extracts concentrations of 25, 50, 75, and 100%. The results were further
analysed using the two-factor ANOVA test. Potential measurement was performed
using a digital voltmeter and a copper/copper sulphate reference electrode. Compressive
strength of each block sample was determined after the experiments. Weight
loss values were obtained from the gravimetric method, and the inhibitor efficiency
was computed from the corrosion rate of each of the tested samples. Results showed
that varied concentration of V. amygdalina and the test exposure time significantly
affect both the corrosion potential of embedded steel rebar in concrete and the pH of
the medium. The extracts gave appreciable corrosion inhibition performance of the
embedded steel rebar at 25 and 50% concentrations with the weight loss of 500
(0.5 g) and 400 mg (0.4 g) and corrosion rates values of 0.000240 and 0.000180 mm/
yr, respectively. The highest inhibition efficiency (60.68%) was achieved at 50 and
39.94% at 25% concentrations, respectively. The 100 and 75% concentrations gave
negative inhibitor values of �51.52 and �20.11%. The ANOVA test confirmed the
results at 95% confidence, and further showed that concentration of V. amygdalina
had greater effect on potential and pH measurements
Keywords
T Technology (General), TJ Mechanical engineering and machinery