Influence of Microsilica on Protection from Chloride‐Induced Corrosion of Reinforcing Steel
Publication: Journal of Materials in Civil Engineering
Volume 5, Issue 2
Abstract
Accelerated corrosion tests were carried out on reinforced‐concrete specimens made with plain and 10% and 20% microsilica‐blended cements. Time to corrosion initiation and corrosion rates of reinforcing steel were measured. Pore fluid was also extracted for analysis from chloride‐bearing hardened cement pastes. Results show that in terms of corrosion‐initiation time, microsilica‐blended cement concretes perform threefold better than the plain cement concrete. After the initiation of corrosion, reinforcing steel in microsilica‐blended cement concrete shows no significant reduction in corrosion rates. Partial cement replacement by microsilica, sharply increases the Cl−/OH− ratio of the pore solution. In addition to the adverse changes in the chemical environment, microsilica blending also brings about significant improvements in the pore structure of the cementitious matrix. The higher corrosion‐initiation time of the microsilica‐blended cement concretes is ascribable to observed pore refinement and segmentation, which retards the diffusion of chloride ions to the steel‐concrete interface, thereby delaying the onset of corrosion. Data developed in this study show microsilica‐blended cement concrete will provide significantly more protection to steel when secondary chlorides permeate into concrete from external sources during service life, compared to situations where primary chlorides are introduced during mixing.
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Information & Authors
Information
Published In
Journal of Materials in Civil Engineering
Volume 5 • Issue 2 • May 1993
Pages: 155 - 169
Copyright
Copyright © 1993 American Society of Civil Engineers.
History
Received: Mar 26, 1991
Published online: May 1, 1993
Published in print: May 1993
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