Durability of Alkali-Activated Slag - Bentonite Cutoff Wall Exposed to Sodium Sulfate and Pb-Zn Solution
This paper addresses the reactive magnesia (MgO) activated ground granulated blast furnace slag (GGBS) blends with bentonite (GMB)as the cutoff wall mixture, compared with Portland Cement with bentonite (CB) for enhancing durability performance. A range of tests have been conducted to investigate the durability of the two batches cutoff wall (GMB and CB) as subjected to sodium sulfated and Pb-Zn solution, including unconfined compressive strength (UCS), hydraulic conductivity, and microstructure analyses with Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The influence of curing age, GMB and CB content, and soaking solution type on the durability are also addressed. The UCS of GMB mixture is lower 73.6% and 11.2% than the CB reference after curing 28-days and 90-days. The hydraulic conductivity of GMB is much lower than the cutoff wall commonly accepted limits of 10−6–10−7 cm/s, regardless of soaking in sodium sulfated and Pb-Zn solution. The microstructural analyses show the hydrotalcite-like phases (Ht) could be formed during the hydration of GMB, and C-S-H could be founded in GMB and CB mixture. The characteristic H-O-H bond stretching is noticed around 3460 and 3620 cm−1, followed by shallow wide transmittances, which indicates the presence of Portlandite (Ca(OH)2) and brucite (Mg(OH)2). The brucite and Ht are confirmed in the SEM images of GMB mixture.
KeywordsCutoff wall MgO GGBS Durability Sodium Sulfated
This research is financially supported by Financial support for this research is partially obtained from the Environmental Protection Scientific Research Project of Jiangsu Province (Grant No. 2016031), National Natural Science Foundation of China (Grant No. 41472258), Natural Science Foundation of Jiangsu Province (Grant No. BK2012022), Colleges and Universities in Jiangsu Province Plans to Graduate Research and Innovation (KYLX16_0242), and the Scientific Research Foundation of Graduate School of Southeast University (Grant No. YBJJ1735).
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