Engineering properties of vertical cutoff walls consisting of reactive magnesia-activated slag and bentonite: workability, strength and hydraulic conductivity

Wu, H.-L., Jin, F. , Ni, J. and Du, Y.-J. (2019) Engineering properties of vertical cutoff walls consisting of reactive magnesia-activated slag and bentonite: workability, strength and hydraulic conductivity. Journal of Materials in Civil Engineering, 31(11), 04019263. (doi: 10.1061/(ASCE)MT.1943-5533.0002908)

[img]
Preview
Text
187481.pdf - Accepted Version

1MB
[img]
Preview
Text
187481Suppl.pdf - Supplemental Material

99kB

Abstract

Soil–cement–bentonite (SCB) vertical cutoff walls are commonly used to control the flow of contaminated groundwater at polluted sites. However, conventional backfill consisting of ordinary portland cement (OPC) is associated with a relatively high CO2 footprint. Potential chemical interactions between OPC and bentonite could also undermine the long-term durability of SCB materials. This paper proposes an innovative backfill material for cutoff walls that is composed of MgO-activated ground granulated blast furnace slag (GGBS), bentonite, and soil. The OPC–soil, OPC–bentonite–soil, and OPC–GGBS–bentonite–soil backfill materials are also tested for comparison purposes. The workability of fresh backfills and unconfined compressive strength of aged backfills are investigated. The hydraulic conductivities of aged backfills permeated with tap water, Na2SO4, and Pb–Zn solutions are assessed. The unconfined compressive strength and hydraulic conductivity of the proposed backfill permeated with tap water are in the range of 230–520 kPa and 1.1×10−10  to  6.3×10−10  m/s after 90 days of curing, respectively, depending on the mix composition. The hydraulic conductivity of the proposed MgO–GGBS–bentonite–soil backfill permeated with sodium sulfate (Na2SO4) or lead–zinc (Pb–Zn) solution is well below the commonly used limit, while the OPC–bentonite–soil backfill shows a significant loss in impermeability. Environmental and economic analyses indicate that, compared with conventional backfill made from OPC–bentonite–soil mixtures, the proposed backfill reduces CO2 emissions by approximately 84.7%–85.1% and costs by 15.3%–16.9%. The environmental and economic advantages will promote the use of MgO-activated GGBS–bentonite mixtures in cutoff walls and lead to their increased application in land remediation projects.

Item Type:Articles
Additional Information:This study was finanically supported by the National Key Research and Development Programme (Grant Nos. 2018YFC1803100 and 2018YFC1802300), the National Natural Science Foundation of China (Grant No. 41877248), the Primary Research & Development Plan of Jiangsu Province (Grant No. BE2017715), the Colleges and Universities in Jiangsu Province Plans for Graduate Research and Innovation (KYLX16_0242), and the Scientific Research Foundation of the Graduate School of Southeast University (Grant No. YBJJ1735).
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Jin, Dr Fei
Authors: Wu, H.-L., Jin, F., Ni, J., and Du, Y.-J.
College/School:College of Science and Engineering > School of Engineering > Infrastructure and Environment
Journal Name:Journal of Materials in Civil Engineering
Publisher:American Society of Civil Engineers
ISSN:0899-1561
ISSN (Online):1943-5533
Published Online:23 August 2019
Copyright Holders:Copyright © 2019 American Society of Civil Engineers
First Published:First published in Journal of Materials in Civil Engineering 31(11): 04019263
Publisher Policy:Reproduced in accordance with the publisher copyright policy

University Staff: Request a correction | Enlighten Editors: Update this record