The Influence of Particle Size and Calcium Content on Performance Characteristics of Metakaolin- and Fly-Ash-Based Geopolymer Gels.

IF 5 3区 化学 Q1 POLYMER SCIENCE
Gels Pub Date : 2024-10-07 DOI:10.3390/gels10100639
Yefan Li, Yanhui Dong, Mohamed R El-Naggar, Fucheng Wang, Yixin Zhao
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Abstract

This research systematically investigates the influence of raw material particle size and calcium content on the geopolymerization process to gain insight into the physical and mechanical properties of geopolymer gels, including setting time, fluidity, pore structure, compressive strength, and leaching characteristics of encapsulated Cr3+ heavy metal ions. Utilizing a diverse range of particle sizes of metakaolin (MK; 3.75, 7.5, and 12 µm) and fly ash (FA; 18, 45, and 75 µm), along with varied calcium levels, this study assesses the dual impact of these factors on the final properties of both metakaolin- and fly-ash-based geopolymers. Employing sophisticated analytical techniques such as Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and Nuclear Magnetic Resonance (NMR), the research meticulously documents alterations in chemical bonding, micro-morphology, and pore structures. Key findings reveal that reducing the size of MK and FA particles to 3.75 and 18 µm, respectively, enhances the compressive strength of their matrices by 128.37 and 297.58%, respectively, compared to their original values (63.59 and 33.87 MPa, respectively) at larger particle sizes. While smaller particle sizes significantly bolster compressive strength, they adversely affect slurry flow and reduce the leaching rates of Cr3+ from MK- and FA-based matrices, reaching 0.42 and 0.75 mg/L at 3.75 and 18 µm, respectively. Conversely, increased calcium content markedly enhances setting times and contributes to the formation of dense microstructures through the production of calcium aluminate silicate hydrate (C-A-S-H) gels, thus improving the overall curing performance and durability of the materials. These insights underline the importance of fine-tuning particle size and calcium content to optimize geopolymer formulations, offering substantial benefits for varied engineering applications and promoting more sustainable construction practices.

粒度和钙含量对偏高岭土和粉煤灰基土工聚合物凝胶性能特征的影响
本研究系统地探讨了原材料粒度和钙含量对土工聚合过程的影响,以深入了解土工聚合凝胶的物理和机械特性,包括凝结时间、流动性、孔隙结构、抗压强度和包裹 Cr3+ 重金属离子的浸出特性。本研究利用不同粒径的偏高岭土(MK;3.75、7.5 和 12 µm)和粉煤灰(FA;18、45 和 75 µm)以及不同的钙含量,评估了这些因素对偏高岭土和粉煤灰基土工聚合物最终特性的双重影响。研究采用扫描电子显微镜 (SEM)、傅立叶变换红外光谱 (FTIR) 和核磁共振 (NMR) 等精密分析技术,细致记录了化学键、微观形态和孔隙结构的变化。主要研究结果表明,将 MK 和 FA 颗粒的尺寸分别减小到 3.75 微米和 18 微米后,其基质的抗压强度分别提高了 128.37% 和 297.58%,而在较大颗粒尺寸时,其原始值分别为 63.59 MPa 和 33.87 MPa。虽然较小的颗粒尺寸可显著提高抗压强度,但它们会对泥浆流动产生不利影响,并降低基于 MK 和 FA 的基质中 Cr3+ 的浸出率,在 3.75 和 18 µm 时分别达到 0.42 和 0.75 mg/L。相反,钙含量的增加会明显延长凝固时间,并通过生成水合铝酸硅酸钙(C-A-S-H)凝胶促进致密微结构的形成,从而改善材料的整体固化性能和耐久性。这些见解强调了微调粒度和钙含量对优化土工聚合物配方的重要性,可为各种工程应用带来巨大益处,并促进更可持续的建筑实践。
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
Gels
Gels POLYMER SCIENCE-
CiteScore
4.70
自引率
19.60%
发文量
707
审稿时长
11 weeks
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