CSIR- National Metallurgical Laboratory, Jamshedpur 831 007, India.
J Hazard Mater. 2020 Apr 5;387:121673. doi: 10.1016/j.jhazmat.2019.121673. Epub 2019 Nov 12.
The potential for practical application of fly ash, zinc slag and their blends for geopolymer synthesis at ambient temperature have been investigated in this paper. Fly ash is an alumino-silicate byproduct suitable for geopolymer reaction, but its low reactivity at ambient condition is the restriction of its bulk utilization. Above limitation can be overcome by blending with zinc slag (ZS). Additionally, ZS contains heavy and toxic metals (Pb, Zn, Cr, Cd, As), which can be stabilize in Al-Si based geopolymer network structure. Isothermal conduction calorimetry (ICC) is used to monitor the geopolymer reaction with time. Slag rich specimens are characterized with higher rate of reaction with augmented peak. The mineralogy and microstructure of the geopolymers have been examined through X-ray diffraction and scanning electron microscope. The detected chief reaction product is N-(C)-A-S-H and C-(N)-A-S-H type hydrated gel. Continual improvement of compressive strength of the geopolymers with increasing slag content is explained with higher degree of reaction, formation of more reaction products and development of compact microstructure. According to toxicity characteristic leaching procedure (TCLP), toxic metals leaching is within permissible limit. Paver blocks using 40-80 wt% ZS has been developed, which meets IS 15,658: 2006 standard and comply with US-EPA specification.
本文研究了粉煤灰、锌渣及其混合物在环境温度下合成地质聚合物的实际应用潜力。粉煤灰是一种适合地质聚合物反应的铝硅酸盐副产品，但在环境条件下其低反应性是其大量利用的限制。通过与锌渣（ZS）混合可以克服这一限制。此外，ZS 含有重金属和有毒金属（Pb、Zn、Cr、Cd、As），这些金属可以在 Al-Si 基地质聚合物网络结构中稳定下来。等温传导量热法（ICC）用于监测地质聚合物随时间的反应。富含矿渣的试样具有更高的反应速率和增强的峰值。通过 X 射线衍射和扫描电子显微镜对地质聚合物的矿物学和微观结构进行了研究。检测到的主要反应产物是 N-(C)-A-S-H 和 C-(N)-A-S-H 型水合凝胶。随着渣含量的增加，地质聚合物抗压强度不断提高，这可以用更高的反应程度、更多反应产物的形成和更致密的微观结构来解释。根据毒性特征浸出程序（TCLP），有毒金属的浸出在允许范围内。已开发出使用 40-80wt% ZS 的铺路砖，符合 IS 15,658:2006 标准和美国环保署规范。
