Free and bound chloride relationships affecting reinforcement cover in alkali activated concrete

MANGAT, Pal and OJEDOKUN, Olalekan O (2020). Free and bound chloride relationships affecting reinforcement cover in alkali activated concrete. Cement and Concrete Composites, p. 103692.

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Abstract

This paper investigates the free chloride profiles, diffusion parameters and chloride binding capacity of an alkali activated concrete (AACM) together with a control Portland cement (PC) concrete. Ggbs based AACM concrete specimens with different molarity of activator were exposed to a 5% NaCl solution for 540days to determine their free chloride diffusion properties. The relationships between the free and bound chloride concentration were determined by applying Freundlich and Langmuir isotherms. The required cover to steel reinforcement for corrosion prevention is derived to satisfy the limiting thresholds of free and bound chloride concentrations. The results show that Fick's second law of diffusion applies to the free chloride profiles of AACM concrete and provides higher values of diffusion coefficients than a similar grade of PC concrete. The relationship between the free and bound chlorides is defined by the Langmuir isotherm. PC concrete has higher chloride binding capacity than AACM concrete for both water and acid soluble chlorides. Less concrete cover to steel reinforcement is required in AACM than PC concrete when calculated by using the bound chloride concentration threshold limit. The values of cover based on the corresponding free chloride limit in AACM concrete are higher than its bound chloride values.

Item Type:	Article
Uncontrolled Keywords:	0904 Chemical Engineering; 0905 Civil Engineering; 1202 Building; Building & Construction
Identification Number:	https://doi.org/10.1016/j.cemconcomp.2020.103692
Page Range:	p. 103692
SWORD Depositor:	Symplectic Elements
Depositing User:	Symplectic Elements
Date Deposited:	02 Jun 2020 14:27
Last Modified:	29 May 2021 01:18
URI:	https://shura.shu.ac.uk/id/eprint/26401

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