Hydraulic conductivity and self-healing performance of Engineered Cementitious Composites exposed to Acid Mine Drainage

Hao-Liang Wu; Yan-Jun Du; Jing Yu; Yu-Ling Yang; Victor C Li

doi:10.1016/j.scitotenv.2020.137095

Hydraulic conductivity and self-healing performance of Engineered Cementitious Composites exposed to Acid Mine Drainage

Sci Total Environ. 2020 May 10:716:137095. doi: 10.1016/j.scitotenv.2020.137095. Epub 2020 Feb 4.

Authors

Hao-Liang Wu¹, Yan-Jun Du², Jing Yu³, Yu-Ling Yang⁴, Victor C Li⁵

Affiliations

¹ Jiangsu Key Laboratory of Urban Underground Engineering & Environmental Safety, Institute of Geotechnical Engineering, Southeast University, Nanjing 210096, China; Department of Civil and Environmental Engineering, Hong Kong University of Science and Technology, Hong Kong SAR, China; Department of Civil and Environmental Engineering, University of Michigan, Ann Arbor, MI 48105, USA.
² Jiangsu Key Laboratory of Urban Underground Engineering & Environmental Safety, Institute of Geotechnical Engineering, Southeast University, Nanjing 210096, China. Electronic address: duyanjun@seu.edu.cn.
³ Department of Civil and Environmental Engineering, Hong Kong University of Science and Technology, Hong Kong SAR, China.
⁴ Jiangsu Key Laboratory of Urban Underground Engineering & Environmental Safety, Institute of Geotechnical Engineering, Southeast University, Nanjing 210096, China.
⁵ Department of Civil and Environmental Engineering, University of Michigan, Ann Arbor, MI 48105, USA.

PMID: 32059325
DOI: 10.1016/j.scitotenv.2020.137095

Abstract

Engineered Cementitious Composite (ECC) is proposed as a promising vertical cutoff wall material to contain acid mine drainage (AMD). The study presents comprehensive investigations of hydraulic conductivity of ECC permeated with AMD and self-healing of ECC subjected to wet-dry cycles. The effectiveness of incorporating reactive magnesia (MgO) into ECC for self-healing enhancement is also investigated. The chemical species formed in ECC and MgO-ECC specimens after exposure to AMD are investigated via SEM, FTIR, XRD and TGA analyses. The results show hydraulic conductivity of un-cracked and cracked ECC and MgO-ECC specimens pre-strained up to 1.32% is below commonly accepted limits of 10^-8 m/s when permeated with AMD. The self-healing capacity of ECC specimens subjected to wet-dry cycles using both tap water and AMD as immersing liquids is improved by MgO addition. MgO addition is also beneficial for reducing hydraulic conductivity of un-cracked and cracked ECC specimens permeated with AMD. MgO addition results formation of new self-healing products including hydromagnesite and brucite when exposed to tap water, and hydrotalcite-like phase (Ht) when exposed to AMD.

Keywords: Acid mining drainage; Engineered cementitious composite; Hydraulic conductivity; Reactive MgO; Self-healing.