Two-phase changes in workability of sand-bentonite mixture triggered by seawater and binder during seepage cut-off wall construction in marine environment

Phenomenal sea level rise is exacerbating the risk of seawater intrusion in coastal areas, especially those with sandy soil, causing land erosion. Seepage cut-off walls made of in-situ sand, bentonite and binder can be employed. However, the presence of salts in soil is detrimental to water retentio...

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Main Authors:	Ting, Matthew Zhi Yeon, Li, Wentao, Yi, Yaolin
其他作者:	School of Civil and Environmental Engineering
格式:	Article
語言:	English
出版:	2023
主題:	Engineering Bentonite Binder
在線閱讀:	https://hdl.handle.net/10356/171284
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id	sg-ntu-dr.10356-171284
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spelling	sg-ntu-dr.10356-1712842025-03-14T15:34:02Z Two-phase changes in workability of sand-bentonite mixture triggered by seawater and binder during seepage cut-off wall construction in marine environment Ting, Matthew Zhi Yeon Li, Wentao Yi, Yaolin School of Civil and Environmental Engineering Engineering Bentonite Binder Phenomenal sea level rise is exacerbating the risk of seawater intrusion in coastal areas, especially those with sandy soil, causing land erosion. Seepage cut-off walls made of in-situ sand, bentonite and binder can be employed. However, the presence of salts in soil is detrimental to water retention ability of bentonite, which can be aggravated by binder-induced cation exchange reactions, causing constructability issues for two-phase cut-off walls. Therefore, this study aims to evaluate the workability properties, including flowability and bleeding of sand-bentonite-binder mixture in seawater environment. The mechanism of decrease in water retention of bentonite has been investigated using Atterberg limits, X-ray diffration (XRD) and scanning electron microscope (SEM) analyses. In phase-one construction, seawater significantly increased flowability of sand-bentonite mixture. During the second phase, binder inclusion increased flowability even further. Given comparable flowability, the bleeding in sand-bentonite-binder mixture containing seawater was much greater than in the non-seawater environment. This was ascribed to a loss in water retention capacity of bentonite, in which external cations from seawater and binder exchanged with bentonite, resulting in reduction in liquid limit. The Na-based montmorillonite was transformed into Ca-based montmorillonite, causing the morphology of bentonite particles to flocculate. Despite this, the study discovered a feasible sand-bentonite-binder mixture including reactive magnesia (MgO)-activated ground granulated blast-furnace slag (GGBS) and seawater-resistant bentonite, which impeded the increase in workability. Ministry of Education (MOE) Submitted/Accepted version The authors express gratitude towards the research grant supported by the Ministry of Education, Singapore, under its Academic Research Fund Tier 2 (MOE-T2EP50220-0004). 2023-10-18T04:28:34Z 2023-10-18T04:28:34Z 2023 Journal Article Ting, M. Z. Y., Li, W. & Yi, Y. (2023). Two-phase changes in workability of sand-bentonite mixture triggered by seawater and binder during seepage cut-off wall construction in marine environment. Construction and Building Materials, 401, 132900-. https://dx.doi.org/10.1016/j.conbuildmat.2023.132900 0950-0618 https://hdl.handle.net/10356/171284 10.1016/j.conbuildmat.2023.132900 2-s2.0-85167986778 401 132900 en MOE-T2EP50220-0004 Construction and Building Materials © 2023 Elsevier Ltd. All rights reserved. This article may be downloaded for personal use only. Any other use requires prior permission of the copyright holder. The Version of Record is available online at http://doi.org/10.1016/j.conbuildmat.2023.132900 application/pdf
institution	Nanyang Technological University
building	NTU Library
continent	Asia
country	Singapore Singapore
content_provider	NTU Library
collection	DR-NTU
language	English
topic	Engineering Bentonite Binder
spellingShingle	Engineering Bentonite Binder Ting, Matthew Zhi Yeon Li, Wentao Yi, Yaolin Two-phase changes in workability of sand-bentonite mixture triggered by seawater and binder during seepage cut-off wall construction in marine environment
description	Phenomenal sea level rise is exacerbating the risk of seawater intrusion in coastal areas, especially those with sandy soil, causing land erosion. Seepage cut-off walls made of in-situ sand, bentonite and binder can be employed. However, the presence of salts in soil is detrimental to water retention ability of bentonite, which can be aggravated by binder-induced cation exchange reactions, causing constructability issues for two-phase cut-off walls. Therefore, this study aims to evaluate the workability properties, including flowability and bleeding of sand-bentonite-binder mixture in seawater environment. The mechanism of decrease in water retention of bentonite has been investigated using Atterberg limits, X-ray diffration (XRD) and scanning electron microscope (SEM) analyses. In phase-one construction, seawater significantly increased flowability of sand-bentonite mixture. During the second phase, binder inclusion increased flowability even further. Given comparable flowability, the bleeding in sand-bentonite-binder mixture containing seawater was much greater than in the non-seawater environment. This was ascribed to a loss in water retention capacity of bentonite, in which external cations from seawater and binder exchanged with bentonite, resulting in reduction in liquid limit. The Na-based montmorillonite was transformed into Ca-based montmorillonite, causing the morphology of bentonite particles to flocculate. Despite this, the study discovered a feasible sand-bentonite-binder mixture including reactive magnesia (MgO)-activated ground granulated blast-furnace slag (GGBS) and seawater-resistant bentonite, which impeded the increase in workability.
author2	School of Civil and Environmental Engineering
author_facet	School of Civil and Environmental Engineering Ting, Matthew Zhi Yeon Li, Wentao Yi, Yaolin
format	Article
author	Ting, Matthew Zhi Yeon Li, Wentao Yi, Yaolin
author_sort	Ting, Matthew Zhi Yeon
title	Two-phase changes in workability of sand-bentonite mixture triggered by seawater and binder during seepage cut-off wall construction in marine environment
title_short	Two-phase changes in workability of sand-bentonite mixture triggered by seawater and binder during seepage cut-off wall construction in marine environment
title_full	Two-phase changes in workability of sand-bentonite mixture triggered by seawater and binder during seepage cut-off wall construction in marine environment
title_fullStr	Two-phase changes in workability of sand-bentonite mixture triggered by seawater and binder during seepage cut-off wall construction in marine environment
title_full_unstemmed	Two-phase changes in workability of sand-bentonite mixture triggered by seawater and binder during seepage cut-off wall construction in marine environment
title_sort	two-phase changes in workability of sand-bentonite mixture triggered by seawater and binder during seepage cut-off wall construction in marine environment
publishDate	2023
url	https://hdl.handle.net/10356/171284
_version_	1827070681714524160

Two-phase changes in workability of sand-bentonite mixture triggered by seawater and binder during seepage cut-off wall construction in marine environment

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