Optimization of microstructure and mechanical performance of clay-rich sand-washing slurry-based geopolymers

IF 5.3 2区 地球科学 Q2 CHEMISTRY, PHYSICAL
Weijie Chen , Biqin Dong , Kai-Di Peng , Qingrui Yang , Yanshuai Wang , Shuxian Hong
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Abstract

As a byproduct of sand-washing process, sand-washing slurry (SWS) showed a potential geopolymer precursor due to the abundant clay minerals. This study investigated the impact of calcination temperature of SWS and SiO2/Na2O ratio of alkaline solution on the microstructure and mechanical properties of SWS-based geopolymers. The analysis results indicated that at a calcination temperature of 550 °C, some clay minerals in SWS underwent a transition from crystalline to amorphous phases, resulting in increased amounts of amorphous Si and Al, thereby enhancing their alkaline reactivity. However, due to the low content of amorphous phases, the formed geopolymer structure was loose, leading to lower compressive strength. Compared to geopolymer treated at 550 °C, the geopolymer produced under temperatures ranging from 650 °C to 750 °C exhibited denser microstructures and higher compressive strength. The improvement in performance was attributed to more clay minerals undergoing dehydroxylation reactions, resulting in more amorphous Si and Al participating in the polymerization reaction. Nevertheless, upon reaching a calcination temperature of 850 °C, the microstructure of the formed geopolymers became loose with diminished compressive strength due to reduced activity of Si and Al in the amorphous phase.

Furthermore, under a calcination temperature of 750 °C, the amorphous content in geopolymers with SiO2/Na2O ratios in the alkaline solution of 0.8 and 1.4 was 62.4 % and 64.5 %, respectively, while decreasing to 54.5 % in geopolymers with a ratio of 2. Geopolymers with a SiO2/Na2O ratio of 1.4 exhibited denser microstructures and higher compressive strength, indicating that alkaline solutions with this ratio promoted the formation of more amorphous materials and enhanced geopolymer strength. These findings suggested that calcination around 750 °C improved the microstructure and mechanical properties of SWS-based geopolymers, with the appropriate SiO2/Na2O ratio in alkaline solutions facilitating geopolymerization.

优化富含粘土的洗砂浆基土工聚合物的微观结构和机械性能
作为洗砂工艺的副产品,洗砂浆(SWS)因含有丰富的粘土矿物而成为一种潜在的土工聚合物前体。本研究探讨了洗砂浆的煅烧温度和碱性溶液中 SiO2/Na2O 的比例对洗砂浆基土工聚合物微观结构和力学性能的影响。分析结果表明,在煅烧温度为 550 ℃ 时,SWS 中的一些粘土矿物发生了从结晶相到无定形相的转变,导致无定形 Si 和 Al 的含量增加,从而提高了它们的碱性反应活性。然而,由于非晶相含量较低,形成的土工聚合物结构松散,导致抗压强度较低。与在 550 °C 温度下处理的土工聚合物相比,在 650 °C 至 750 °C 温度下生产的土工聚合物显示出更致密的微观结构和更高的抗压强度。性能的提高归因于更多的粘土矿物发生了脱羟基反应,导致更多的无定形硅和铝参与聚合反应。然而,当煅烧温度达到 850 ℃ 时,由于无定形相中 Si 和 Al 的活性降低,形成的土工聚合物的微观结构变得疏松,抗压强度降低。SiO2/Na2O 比率为 1.4 的土工聚合物显示出更致密的微观结构和更高的抗压强度,表明该比率的碱性溶液促进了更多无定形材料的形成并提高了土工聚合物的强度。这些研究结果表明,750 ℃左右的煅烧可改善基于SWS的土工聚合物的微观结构和机械性能,碱性溶液中适当的SiO2/Na2O比例可促进土工聚合物的形成。
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来源期刊
Applied Clay Science
Applied Clay Science 地学-矿物学
CiteScore
10.30
自引率
10.70%
发文量
289
审稿时长
39 days
期刊介绍: Applied Clay Science aims to be an international journal attracting high quality scientific papers on clays and clay minerals, including research papers, reviews, and technical notes. The journal covers typical subjects of Fundamental and Applied Clay Science such as: • Synthesis and purification • Structural, crystallographic and mineralogical properties of clays and clay minerals • Thermal properties of clays and clay minerals • Physico-chemical properties including i) surface and interface properties; ii) thermodynamic properties; iii) mechanical properties • Interaction with water, with polar and apolar molecules • Colloidal properties and rheology • Adsorption, Intercalation, Ionic exchange • Genesis and deposits of clay minerals • Geology and geochemistry of clays • Modification of clays and clay minerals properties by thermal and physical treatments • Modification by chemical treatments with organic and inorganic molecules(organoclays, pillared clays) • Modification by biological microorganisms. etc...
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