Because long-term leachate migration through a hydraulic barrier is inevitable, compacted clay and cementitious liners are commonly used as ‘active-passive’ liners to attenuate percolated leachate. The scarcity of suitable clay and because of the CO2 emitted during the production of Portland cement as well as drying shrinkage, flow rate due to consolidation, limited attenuation capacity, and chemical instability may mean that these are not the best choices of materials to use for this purpose. An environmentally friendly method to improve the properties of local clay and provision for a long-term physical and chemical containment are essential. Geopolymers can be environmentally friendly substitutes for Portland cement to improve soil properties, not just because of the reduced carbon dioxide emission, but also because of its superior physical and chemical properties, as well as significant early strength, reduced shrinkage, freeze-thaw resistance, long-term durability, and attenuation capacity. According to previous studies, class-F fly ash-based geopolymers activated with NaOH exhibit superior attenuation capacity and long-term durability. The presence of silica, alumina, and iron oxides and the lack of calcium oxide play pivotal roles in the acceptable attenuation capacity and chemical stability of class-F fly ash. Accordingly, a clay-fly ash geopolymer may also work as a sustainable liner with appropriate physical and chemical performance. Clay can also participate in the geopolymerization process as an alumino-silicate precursor. All components of clay-fly ash geopolymers possess acceptable adsorption capacity. The type and percentage of the constituent raw materials control the attenuation capacity and physical properties of final products, however. The porosity and conductivity of typical geopolymers are related to the activator type and concentration, water content, and curing condition. Furthermore, the properties of liner materials can be adjusted with respect to the target contaminants. The present study aimed to present a comprehensive review of the relevant studies to highlight the properties required.

中文翻译：

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粉煤灰地质聚合物在主动-被动衬管设计中的潜在用途：综述

由于通过水力屏障的长期渗滤液迁移是不可避免的，压实粘土和水泥衬里通常用作“主动-被动”衬里以减弱渗滤液。合适粘土的稀缺性以及由于波特兰水泥生产过程中排放的 CO2 以及干燥收缩、固结导致的流速、有限的衰减能力和化学不稳定性可能意味着这些不是用于生产的最佳材料选择这个目的。一种环境友好的方法来改善当地粘土的特性并提供长期的物理和化学遏制是必不可少的。地质聚合物可以作为波特兰水泥的环保替代品来改善土壤性质，不仅仅是因为减少了二氧化碳排放，还因为其优越的物理和化学性能，以及显着的早期强度、降低的收缩率、抗冻融性、长期耐用性和衰减能力。根据之前的研究，用 NaOH 活化的 F 类粉煤灰基地质聚合物表现出优异的衰减能力和长期耐久性。二氧化硅、氧化铝和氧化铁的存在以及氧化钙的缺乏对 F 级飞灰可接受的衰减能力和化学稳定性起着关键作用。因此，粘土粉煤灰地质聚合物也可以作为具有适当物理和化学性能的可持续衬垫。粘土也可以作为铝硅酸盐前体参与地质聚合过程。粘土粉煤灰地质聚合物的所有组分都具有可接受的吸附能力。然而，组成原材料的类型和百分比控制着最终产品的衰减能力和物理特性。典型地质聚合物的孔隙率和电导率与活化剂类型和浓度、含水量和固化条件有关。此外，衬里材料的特性可以根据目标污染物进行调整。本研究旨在对相关研究进行全面审查，以突出所需的特性。衬里材料的特性可以根据目标污染物进行调整。本研究旨在对相关研究进行全面审查，以突出所需的特性。衬里材料的特性可以根据目标污染物进行调整。本研究旨在对相关研究进行全面审查，以突出所需的特性。