Cementitious property of NaAlO2-activated Ge slag as cement supplement
来源期刊：International Journal of Minerals Metallurgy and Materials2019年第12期
论文作者：Hua-zhe Jiao Shu-fei Wang Ai-xiang Wu Hui-ming Shen Jian-dong Wang
文章页码：1594 - 1603
摘 要：Germanium（Ge）, a waste residue leaching from zinc（Zn） smelting process, has potential cementitious properties and could be recycled as a cement supplement activated by chemical reagents. In this work, a test was conducted to determine the hydration properties of Ge slag-cement-based composites with Ge slag（GS）/ordinary Portland cement（PC） contents of 0 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, and 25 wt% and water-to-binder ratio（w/b） of 0.4. The activators Ca（OH）2, AlCl3, NaAlO2, and Na2CO3 were mixed under 1 wt%, 2 wt%, 3 wt%, and 4 wt% dosages of GS weight. The composition and microstructure of the hydration products were investigated by the combined approaches of X-ray diffraction（XRD）, thermogravimetry–differential scanning calorimetry（TG-DSC）, scanning electron microscopy（SEM）, and energy-dispersive X-ray spectroscopy（EDS）. First, the GS cementitious property is attributed to the high content of CaSO4·2H2O. Second, the activators affected the acceleration performance in the following order: NaAlO2, Na2CO3, AlCl3, and Ca（OH）2. More importantly, the 28-day unconfined compressive strength（UCS） is 45.34 MPa at the optimum formula of 0.6 wt% NaAlO2, 15 wt% GS, and 85 wt% PC, which is 9.16% higher than the control. Thus, NaAlO2 is beneficial for the ettringite（AFt） generation, resulting in the C–S–H structure compaction. However, the Zn2+ residue inhibited the AFt formation, representing an important challenge to the strength growth with curing age. Consequently, the GS could be recycled as a supplement to the cement under the activator NaAlO2.
Hua-zhe Jiao1，Shu-fei Wang1，Ai-xiang Wu2，Hui-ming Shen2，Jian-dong Wang2
1. International Joint Research Laboratory of Henan Province for Underground Space Development and Disaster Prevention, Henan Polytechnic University2. School of Civil and Resource Engineering, University of Science and Technology Beijing
摘 要：Germanium（Ge）, a waste residue leaching from zinc（Zn） smelting process, has potential cementitious properties and could be recycled as a cement supplement activated by chemical reagents. In this work, a test was conducted to determine the hydration properties of Ge slag-cement-based composites with Ge slag（GS）/ordinary Portland cement（PC） contents of 0 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, and 25 wt% and water-to-binder ratio（w/b） of 0.4. The activators Ca（OH）2, AlCl3, NaAlO2, and Na2CO3 were mixed under 1 wt%, 2 wt%, 3 wt%, and 4 wt% dosages of GS weight. The composition and microstructure of the hydration products were investigated by the combined approaches of X-ray diffraction（XRD）, thermogravimetry–differential scanning calorimetry（TG-DSC）, scanning electron microscopy（SEM）, and energy-dispersive X-ray spectroscopy（EDS）. First, the GS cementitious property is attributed to the high content of CaSO4·2H2O. Second, the activators affected the acceleration performance in the following order: NaAlO2, Na2CO3, AlCl3, and Ca（OH）2. More importantly, the 28-day unconfined compressive strength（UCS） is 45.34 MPa at the optimum formula of 0.6 wt% NaAlO2, 15 wt% GS, and 85 wt% PC, which is 9.16% higher than the control. Thus, NaAlO2 is beneficial for the ettringite（AFt） generation, resulting in the C–S–H structure compaction. However, the Zn2+ residue inhibited the AFt formation, representing an important challenge to the strength growth with curing age. Consequently, the GS could be recycled as a supplement to the cement under the activator NaAlO2.
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