Nanoscale mechanism of ions immobilized by the geopolymer: A molecular dynamics study

Hou, Dongshuai and Zhang, Jinglin and Pan, Wang and Zhang, Yue and Zhang, Zuhua (2020) Nanoscale mechanism of ions immobilized by the geopolymer: A molecular dynamics study. Journal of Nuclear Materials, 528 (Article 151841). pp. 1-10. ISSN 0022-3115


Abstract

In this work, the impact of layered double hydroxides (LDHs) on sulfate attack resistance of concrete was explored. Replacement level of cement by calcined Mg-Al-CO3 LDHs was 2%. Mechanism of ion exchange and memory effects of LDHs has been revealed from structure evolution and adsorption behavior aspects of LDHs in aqueous solution. The efficiency of calcined LDHs in sulfate attack resistance was also assessed in terms of microstructure and compressive strength loss of concrete. The experimental results show that structure regeneration of calcined LDHs can be achieved based on memory effect and ion adsorption after mixing with solution. Calcined LDHs presents high sulfate ion adsorption capacity ascribes to the availability of large amounts of vacancy between the layers. The optimal dosage of calcined LDHs for achieving high uptake efficiency of sulfate ion surpasses 3.0 g/L. Langmuir isotherm suits more to describe the adsorption of sulfate ion on calcined LDHs compared with Freundlich model. Thermodynamic parameters calculation indicates the endothermic behavior (the maximum value is obtained at 40 °C) and spontaneous nature of sulfate ion adsorption on the calcined LDHs. Calcined LDHs exhibits improving effect on pore refinement. Calcined LDHs improves concrete strength and therefore enhances sulfate attack resistance especially at longer exposure days.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Files associated with this item cannot be displayed due to copyright restrictions.
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 Astrophysics (1 Aug 2018 -)
Date Deposited: 31 Jan 2020 04:54
Last Modified: 08 May 2020 01:50
Uncontrolled Keywords: Layered double hydroxides; Sulfate attack; Adsorption; Compressive strength; NASH gel; Molecular dynamics; Ions immobilization; Hydrogen bond; Hydration time
Fields of Research : 09 Engineering > 0905 Civil Engineering > 090503 Construction Materials
Socio-Economic Objective: B Economic Development > 87 Construction > 8703 Construction Materials Performance and Processes > 870301 Cement and Concrete Materials
Identification Number or DOI: https://doi.org/10.1016/j.jnucmat.2019.151841
URI: http://eprints.usq.edu.au/id/eprint/37680

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