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https://hdl.handle.net/10356/171284
Title: | Two-phase changes in workability of sand-bentonite mixture triggered by seawater and binder during seepage cut-off wall construction in marine environment | Authors: | Ting, Matthew Zhi Yeon Li, Wentao Yi, Yaolin |
Keywords: | Engineering::Civil engineering | Issue Date: | 2023 | Source: | 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 | Project: | MOE-T2EP50220-0004 | Journal: | Construction and Building Materials | Abstract: | 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. | URI: | https://hdl.handle.net/10356/171284 | ISSN: | 0950-0618 | DOI: | 10.1016/j.conbuildmat.2023.132900 | Schools: | School of Civil and Environmental Engineering | Rights: | © 2023 Elsevier Ltd. All rights reserved. | Fulltext Permission: | none | Fulltext Availability: | No Fulltext |
Appears in Collections: | CEE Journal Articles |
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