Geomechanical Properties of Clay Stabilised with Fly Ash-Based Geopolymer Subjected to Long-Term Sulfate Attack

IF 2.3 Q2 ENGINEERING, GEOLOGICAL
Hayder H. Abdullah, Mohamed A. Shahin
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引用次数: 0

Abstract

Abstract Fly ash-based geopolymers have emerged as an eco-friendly alternative binder compared to conventional Portland cement for soil stabilisation. However, the gap in the current literature is the lack of a comprehensive study regarding the geomechanical behaviour of fly ash geopolymer-treated clay subjected to long-term sulfate attack, particularly in terms of potential ettringite formation and the corresponding impact on cementitious soil structure. The goal of this paper is to address this knowledge gap and provide a comprehensive study to fulfil it. In this work, sulfate attack was simulated by submerging geopolymer-treated clay specimens in two distinct sulfate-based solutions (i.e., sodium and magnesium), for one year. Subsequently, comparative analyses of the geomechanical and microstructural changes in geopolymer-treated clay under various curing conditions were conducted through unconfined compressive strength, direct shear, volume change and microscopic tests. The findings indicate that the addition of geopolymer for the stabilisation of clay soil significantly improves soil strength without affecting the soil volumetric response. Although the clay used exhibited similar qualitative stress–strain behaviour across all simulated attacks, notable quantitative differences emerged in the peak strength, stiffness and shear strength parameters. Such discrepancies can primarily be attributed to the varying buffering capacities (i.e., pH changes associated with acidification) of the sulfate solutions and the subsequent residual pH, cementitious product formation and strength enhancement within the treated clay.
硫酸盐长期侵蚀下粉煤灰基地聚合物稳定粘土的地质力学特性
与传统的波特兰水泥相比,粉煤灰基地聚合物已经成为一种环保的替代粘合剂,用于土壤稳定。然而,目前文献的空白是缺乏关于粉煤灰地聚合物处理粘土在长期硫酸盐侵蚀下的地质力学行为的全面研究,特别是在潜在的钙矾石形成和对胶凝土结构的相应影响方面。本文的目标是解决这一知识差距,并提供一个全面的研究,以满足它。在这项工作中,通过将经地聚合物处理的粘土样品浸泡在两种不同的硫酸盐基溶液(即钠和镁)中一年来模拟硫酸盐的侵蚀。随后,通过无侧限抗压强度、直剪、体积变化和细观试验,对比分析了不同养护条件下地聚合物处理粘土的地质力学和微观结构变化。研究结果表明,在不影响土壤体积响应的情况下,添加地聚合物稳定粘土可显著提高土壤强度。尽管所使用的粘土在所有模拟攻击中表现出类似的定性应力-应变行为,但在峰值强度、刚度和抗剪强度参数中出现了显著的定量差异。这种差异主要归因于硫酸盐溶液的不同缓冲能力(即与酸化相关的pH值变化)以及随后的残余pH值、胶凝产物的形成和处理后粘土的强度增强。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
CiteScore
4.20
自引率
17.20%
发文量
68
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