Corrosion protection of reinforcing steel with kelp extract as corrosion inhibitor.

This study aims to evaluate the effectiveness of kelp extract as a corrosion inhibitor to resist the steel corrosion in mortars. The solvent extraction methods with several technologies were applied to prepare the kelp extracts, and their inhibiting efficacies were compared in the saturated calcium hydroxide solution. Besides, the extract with the best inhibition effect in the solution was applied in mortars. Several electrochemical techniques, compressive strength and flexural strength tests and visual inspection of steel surface were performed. Results indicate that all the extracts have an ability of inhibiting the steel corrosion in the solution. In principle, they are classified as a mixed inhibitor. The extract prepared by using 0·1 mol L⁻¹ NaOH as a solvent exhibits a good inhibition effect in mortars. However, it decreases the compressive strength and flexural strength of mortar. Accordingly, the kelp extract is suggested to be applied cautiously as an inhibitor in the reinforced concrete. [ABSTRACT FROM AUTHOR]