Chloride diffusion in alkali-activated fly ash/slag concretes: Role of slag content, water/binder ratio, alkali content and sand-aggregate ratio

Zhang, Jingxiao and Ma, Yuwei and Zheng, Jiazheng and Hu, Jie and Fu, Jiyang and Zhang, Zuhua and Wang, Hao (2020) Chloride diffusion in alkali-activated fly ash/slag concretes: Role of slag content, water/binder ratio, alkali content and sand-aggregate ratio. Construction and Building Materials, 261:119940. pp. 1-12. ISSN 0950-0618


Abstract

The widespread application of alkali-activated fly ash/slag (AAFS) concrete requires the satisfaction of a series of performance criteria both from its early age properties (e.g. workability, strength) and long-term stability. In this study, long-term (till 180 days) natural chloride diffusion tests were conducted to evaluate the chloride diffusion in AAFS concretes prepared with different slag content, water/binder (w/b) ratio, alkali content, and sand-aggregate ratio. The results revealed that AAFS concretes obtained in this study were generally regarded as flow/high flow concretes (slump > 100 mm) with compressive strength > 50 MPa at 28 day. The free chloride diffusion coefficient (Df) of AAFS concretes was between 0.4 and 1.8 × 10-12 m2/s. The slag content and w/b were found as dominant parameters affecting the long-term chloride transport in AAFS concretes, while the sand-aggregate ratio presented a limited effect. The formation of more C-A-S-H gels (by increasing slag content ≥ 50%), and lower w/b (≤0.45) at Na2O content of ∼ 5% was preferred for AAFS concretes with good workability, strength and durability. MIP results indicated that capillary pores in AAFS reached percolation and became disconnected after 180 days. The long-term chloride diffusivity of AAFS concretes was closely related to the threshold pore diameter and volume of pores > 5 nm. The more larger pores, the higher chloride diffusion coefficient was.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Future Materials (1 Jan 2017 -)
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Future Materials (1 Jan 2017 -)
Date Deposited: 07 Mar 2022 03:15
Last Modified: 28 Mar 2022 04:09
Uncontrolled Keywords: Alkali-activated concrete; Chloride diffusion coefficient; Early age properties; Natural chloride diffusion tests; Pore structure
Fields of Research (2008): 09 Engineering > 0905 Civil Engineering > 090503 Construction Materials
09 Engineering > 0912 Materials Engineering > 091202 Composite and Hybrid Materials
Fields of Research (2020): 40 ENGINEERING > 4016 Materials engineering > 401602 Composite and hybrid materials
40 ENGINEERING > 4005 Civil engineering > 400505 Construction materials
Socio-Economic Objectives (2008): E Expanding Knowledge > 97 Expanding Knowledge > 970109 Expanding Knowledge in Engineering
Socio-Economic Objectives (2020): 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280110 Expanding knowledge in engineering
Identification Number or DOI: https://doi.org/10.1016/j.conbuildmat.2020.119940
URI: http://eprints.usq.edu.au/id/eprint/46465

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