Chloride-initiated corrosion in alkali activated reinforced concrete

Published on Jan 1, 2021in Cement & Concrete Composites7.586
· DOI :10.1016/J.CEMCONCOMP.2020.103823
Pal Mangat18
Estimated H-index: 18
(SHU: Sheffield Hallam University),
Olalekan Ojedokun5
Estimated H-index: 5
(SHU: Sheffield Hallam University),
Paul Lambert11
Estimated H-index: 11
(SHU: Sheffield Hallam University)
Source
Abstract
Abstract The use of ordinary Portland cement (PC) as the principal binder in concrete brings with it significant environmental challenges through the consumption of fossil fuels and emission of carbon dioxide (CO2) during cement production. Concrete specimens made with an alkali activated cementitious material (AACM) produced from an alternative binder and conventional Portland cement concrete were exposed to corrosion inducing environments for 1750 days to monitor their relative durability. AACM concrete shows higher corrosion potential Ecorr and corrosion current densities Icorr than PC concrete due to a reducing environment around the steel surface in AACM concrete, caused by high sulfide concentration in the pore solution. Corrosion resistance of the AACM concretes increases with increasing molarity of the alkali activator, at a constant liquid to binder ratio. The threshold Cl−/OH− value for pitting corrosion initiation in the AACM concrete is between 2.1 and 2.8 compared with 1.08 for the control PC concrete. The AACM concrete evaluated in this study showed greater resistance to chloride induced corrosion than the PC concrete.
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Many standardised durability testing methods have been developed for Portland cement-based concretes, but require validation to determine whether they are also applicable to alkali-activated materials. To address this question, RILEM TC 247-DTA ‘Durability Testing of Alkali-Activated Materials’ carried out round robin testing of carbonation and chloride penetration test methods, applied to five different alkali-activated concretes based on fly ash, blast furnace slag or metakaolin. The methods a...
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Abstract Alkali activated cementitious material (AACM) concrete and conventional concrete specimens of similar strength, developed for structural applications, were exposed to a 5% NaCl solution. Bound chloride concentrations (water and acid soluble) were determined up to 270 days of chloride exposure. Chloride diffusion profiles with depth and diffusion parameters C0 and Dc were derived from the data for water soluble, acid soluble and total bound chloride concentrations in order to develop lon...
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