Influence of wet-dry cycles on vertical cutoff walls made of reactive magnesia-slag-bentonite-soil mixtures

Wu, H.-L., Jin, F. and Du, Y.-J. (2019) Influence of wet-dry cycles on vertical cutoff walls made of reactive magnesia-slag-bentonite-soil mixtures. Journal of Zhejiang University-SCIENCE A, 20(12), pp. 948-960. (doi: 10.1631/jzus.A1900300)

Abstract

The strength and hydraulic conductivity of vertical cutoff walls consisting of reactive magnesia-activated ground granulated blast furnace slag (GGBS), bentonite, and soil (MSB) have been investigated in previous studies. However, there has been little comprehensive study of the influence of wet-dry cycles on the mechanical and microstructural properties of MSB backfills. In this paper, the durability of MSB backfills when exposed to wet-dry cycles is investigated. The variations in mass change, dry density, pH value, pore size distribution, and mineralogy are discussed. The results show that the mass change of ordinary Portland cement (OPC)-based and MSB backfills increases with respect to wet-dry cycles. The MSB backfills exhibit up to 8.2% higher mass change than OPC-based ones after 10 wet-dry cycles. The dry density, pH value, and unconfined compressive strength of MSB backfill decrease with the increasing number of wet-dry cycles. Increasing the GGBS-MgO content from 5% to 10% in MSB backfills results in 2.1–2.3 times higher strength, corresponding to a reduction of 2%–12% in cumulative pore volume; while increasing the bentonite content slightly reduces the strength of MSB mixtures, corresponding to an increase of cumulative pore volume by 4.6%–7.9%. The hydrotalcite-like phases and calcium silicate hydrate (C-S-H) are the primary hydration products in MSB backfills. Moreover, the continuous wet-dry cycles result in the precipitation of calcite and nesquehonite.

• Item Type: Articles
• Additional Information: Project supported by the National Key Research and Development Program (Nos. 2018YFC1803100 and 2018YFC1802300), the National Natural Science Foundation of China (No. 41877248), and the Primary Research & Development Plan of Jiangsu Province (No. BE2017715), China.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Jin, Dr Fei
• Authors: Wu, H.-L., Jin, F., and Du, Y.-J.
• College/School: College of Science and Engineering > School of Engineering > Infrastructure and Environment
• Journal Name: Journal of Zhejiang University-SCIENCE A
• Publisher: Springer
• ISSN: 1673-565X
• ISSN (Online): 1862-1775
• Published Online: 17 December 2019
• Copyright Holders: Copyright © 2019, Zhejiang University and Springer-Verlag GmbH Germany, part of Springer Nature
• First Published: First published in Journal of Zhejiang University-SCIENCE A 20(12):948-960
• Publisher Policy: Reproduced in accordance with the publisher copyright policy