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

Affiliation

Jiangsu Key Laboratory of Urban Underground Engineering & Environmental Safety, Institute of Geotechnical Engineering, Southeast University, Nanjing 210096, China. Electronic address: [Email]

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,

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