Alvaro Seijas-Da Silva , Víctor Oestreicher , José Rafael Ruiz , Daniel Cosano , Gonzalo Abellán
{"title":"Influence of Al-clustering in the catalytic activity of layered double hydroxides for the Baeyer-Villiger oxidation","authors":"Alvaro Seijas-Da Silva , Víctor Oestreicher , José Rafael Ruiz , Daniel Cosano , Gonzalo Abellán","doi":"10.1016/j.clay.2024.107542","DOIUrl":"10.1016/j.clay.2024.107542","url":null,"abstract":"<div><p>The utilization of efficient and environmentally friendly heterogeneous catalysts in the Baeyer-Villiger (BV) reaction gained significant importance in the field of green chemistry. In this study, the catalytic properties of magnesium-aluminium hydrotalcite in the BV oxidation of cyclic ketones using H<sub>2</sub>O<sub>2</sub> were investigated. The research focused on the influence of two different synthetic routes on the clustering of aluminium centers and its impact on catalytic activity in the Baeyer-Villiger reaction. Surprisingly, the catalyst with a high degree of aluminium clustering exhibited superior performance compared to the ordered aluminium solid. Moreover, the most active catalyst displayed sustained activity even after three successive reaction cycles. This study presented the first report on the influence of trivalent metals in the BV reaction, thus opening up a new avenue for further exploration of such catalysts in the context of Baeyer-Villiger oxidation.</p></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"260 ","pages":"Article 107542"},"PeriodicalIF":5.3,"publicationDate":"2024-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0169131724002904/pdfft?md5=adb4e46941b8f7dd7b2608fa560be32b&pid=1-s2.0-S0169131724002904-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142087366","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Enhanced OSL emission from α- Al2O3 produced in the presence of halloysite nanocrystals","authors":"C.B.B.M. Ferreira , H.P. Labaki , R.R. Gonçalves , E.J. Guidelli","doi":"10.1016/j.clay.2024.107543","DOIUrl":"10.1016/j.clay.2024.107543","url":null,"abstract":"<div><p>Aluminum oxide (Al<sub>2</sub>O<sub>3</sub>) compounds are extensively used in ionizing radiation dosimetry due to their high sensitivity when doped with carbon. However, their production is difficult and expensive, leading to much research on alternative ways to increase its sensitivity. This paper proposes a seed-mediated synthesis of α-Al<sub>2</sub>O<sub>3</sub> by the combustion method with halloysite nanocrystals as seeds, which also have the ability to scavenge heavy metal ions. The dosimetric features were studied by radioluminescence (RL), thermoluminescence (TL), and optically stimulated luminescence (OSL). Scanning electron microscopy images and X-ray diffraction patterns pointed to the halloysite nanotubes (HNT) acting as heterogeneous nucleation seeds, and as adsorber centers for the chromium ions (Cr<sup>3+</sup>), as evidenced by the decreased crystallite size and Cr<sup>3+</sup> RL emission. Decreased TL intensity upon increasing HNT content in addition to the RL data suggested that the Cr<sup>3+</sup> ions strongly participate in the TL emission process as a luminescent center. Remarkable 6-fold enhanced OSL area intensity and 69-fold OSL initial intensity enhancement were registered from the samples seed-mediated by HNT, revealing that, by scavenging Cr<sup>3+</sup>, the HNT eliminated a luminescent center that competes with the OSL emission. Therefore, HNTs are promising nanomaterials to enhance the sensitivity of Al<sub>2</sub>O<sub>3</sub> dosimeters with potential application in medical physics, where a decrease in the density of concurrent luminescent centers and an increase in OSL intensity were evidenced by the presence of HNT in Al<sub>2</sub>O<sub>3</sub>.</p></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"260 ","pages":"Article 107543"},"PeriodicalIF":5.3,"publicationDate":"2024-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142083933","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lihan Kuang , Guanghua Li , Wenjing Ma , Leping Liu , Xuemin Cui
{"title":"Effect of metakaolin on the chloride diffusion properties of alkali-activated slag in an acidic environment","authors":"Lihan Kuang , Guanghua Li , Wenjing Ma , Leping Liu , Xuemin Cui","doi":"10.1016/j.clay.2024.107544","DOIUrl":"10.1016/j.clay.2024.107544","url":null,"abstract":"<div><p>Alkali-activated materials (AAMs) have good resistance to chemical corrosion compared to silicate cements, but the effect of the pH of chloride-containing solutions on the resistance of AAMs to chloride diffusion is not clear. In this paper, the resistance of alkali-activated slag (AAS) with different metakaolin replacement rate to chloride diffusion in HCl/NaCl solution was investigated in terms of mechanical properties, hydration product composition and pore structure. The experimental results show that acidic solutions lead to alkali leaching, and dissolution of gel and hydrotalcite. The capillary pores that appeared in the AAS after the replacement rate of 10% metakaolin resulted in a decrease in the average pore size of the AAS and low depth of chloride diffusion. 30% metakaolin replacement led to a decrease in the diffusion resistance. In HCl solution, the high [AlO<sub>4</sub>]<sup>5−</sup> retention corroded layer was observed in the AAS with 30% metakaolin replacement and this layer slowed down the migration rate of [Cl<sup>−</sup>]. This study shows the promising application of alkali-activated slag/metakaolin in complex chloride solution environments.</p></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"260 ","pages":"Article 107544"},"PeriodicalIF":5.3,"publicationDate":"2024-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142076674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Zhi Li , Guan-Bin Huang , Han Li , Lei Zhang , Zhiqi Liu , Jimena De La Vega , Raquel Sánchez Díaz , Qingwen Zeng , De-Yi Wang
{"title":"Fire-safe and multifunctional epoxy/layered double hydroxide composites via an interfacial catalysis","authors":"Zhi Li , Guan-Bin Huang , Han Li , Lei Zhang , Zhiqi Liu , Jimena De La Vega , Raquel Sánchez Díaz , Qingwen Zeng , De-Yi Wang","doi":"10.1016/j.clay.2024.107545","DOIUrl":"10.1016/j.clay.2024.107545","url":null,"abstract":"<div><p>Aiming to impart epoxy with a phosphorous-free super-efficient fire safety and multifunctions via a facile interface-manipulation protocol, we innovatively proposed a proof of concept of a two-in-one catalytic function via covalently inducing an interfacial supramolecular assembly of Salen-Fe complex on organic layered double hydroxide (LDH-DBS). Various characterizations confirmed the target LDH-DBS@Salen-Fe with a surface-located uniform and ultrathin deposition of Salen-Fe complex, which was conducive to a better nanodispersion in epoxy matrix. An exceptionally low loading of 2 wt% LDH-DBS@Salen-Fe (<em>i.e.</em>, 0.6 % Salen-Fe) endowed epoxy with a UL-94 <em>V</em>-0 level and intensive fire protection with a suppressed peak heat release rate by 45.0 %. An insightful mechanism investigation demonstrated that the interface-located Salen-Fe rapidly catalyzed a charring reaction with an ultrafast formation of protective fire chars to resist an early-stage fire attack. Additionally, relative to EP/2LDH-DBS, a mere 0.6 % Salen-Fe increased the tensile, flexural and impact strength by 39.6 %, 31.5 % and 37.0 %, respectively based on the optimized interface compatibilization. Interestingly, an ultralow loading of Salen-Fe significantly contributed to a degradation recycling of epoxy under a mild condition with mass loss after 7 h treatment 392.8 % higher than its counterpart via catalytically promoting the generation of CHCOO∙ and HO∙ at the interface. In perspective, an interfacial supramolecular assembly of two-in-one catalysts exploits a novel route towards a phosphorous-free fire-safe and multifunctionally reinforced polymers.</p></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"260 ","pages":"Article 107545"},"PeriodicalIF":5.3,"publicationDate":"2024-08-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142058242","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Efficient removal of organic pollutants on sponge-type inorganic adsorbent derived from spent cotton fiber/layered double hydroxides","authors":"Chaoyang Wang , De Yin , Ran Zhang , Feifei Chen","doi":"10.1016/j.clay.2024.107541","DOIUrl":"10.1016/j.clay.2024.107541","url":null,"abstract":"<div><p>For the whole life cycle of the textile industry, the disposal of printing and dyeing wastewater and the reuse of spent fibers were two of the main environmental problems. In this work, activated carbon fiber/layered double oxides (ACF/LDO) were prepared by the pyrolysis of spent cotton fiber/layered double hydroxides (LDH) composite. Compared to 2D structure LDH, 3D hierarchical ACF/LDO was formed by introducing activated carbon nanofibers as a skeleton. ACF/LDO had excellent adsorption properties for organic dye and the maximum adsorption capacity of acid red 27 (AR27) exceeded 800 mg/g. Due to the memory effect of LDH, the interconversion of ACF/LDO to ACF/LDH was observed during the adsorption and regeneration process. Meanwhile, the shrinkage and expansion of adsorbent occurred, which was similar to that of a sponge absorbing water. During the adsorption process, the average pore diameter of the adsorbent increased as ACF/LDO was converted to ACF/LDH, which increased the diffusion of organic dye inside the pores. On the contrary, the specific surface area and pore structure were restored during the regeneration process. Therefore, this composite displayed excellent adsorption capacity and repeatability, with no significant decrease was observed in adsorption capacity even after five consecutive cycles. The adsorption mechanism revealed that the removal of AR27 was dominated by electrostatic attraction and π-π interactions. The experiment provided a new strategy of treating wastewater with waste fiber.</p></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"260 ","pages":"Article 107541"},"PeriodicalIF":5.3,"publicationDate":"2024-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142049041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yue Sun , Aifang Pan , Yuzhao Ma , Jianwu Zhang , Jie Chang , Zhi Wang
{"title":"Kinetics of kaolinite dissolution and hydrosodalite precipitation during alkali leaching of diasporic bauxite","authors":"Yue Sun , Aifang Pan , Yuzhao Ma , Jianwu Zhang , Jie Chang , Zhi Wang","doi":"10.1016/j.clay.2024.107537","DOIUrl":"10.1016/j.clay.2024.107537","url":null,"abstract":"<div><p>Alkali leaching is an effective desilication method for improving the alumina-silica mass ratio (A/S) of bauxite. The paper aims to study the kinetics of kaolinite dissolution and hydrosodalite precipitation during alkali leaching of kaolinite-rich diasporic bauxite. Alkali leaching of bauxite in NaOH solutions was studied at Na<sub>2</sub>O concentrations of 200–260 g/L, temperatures of 90–105 °C, and times of 30–150 min. The leached bauxites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) techniques. The rate equations describing kaolinite dissolution and hydrosodalite precipitation were derived by fitting the Avrami model. The results show that kaolinite with finer particle sizes was preferentially dissolved during alkali leaching, providing a material basis for the precipitation of hydrosodalite. Hydrosodalite was heterogeneously nucleated on the dissolved edges of some kaolinite and grew in both one- and two-dimensions, presenting acicular and lamellar morphology. The dissolution rate of kaolinite and the crystallization mechanism of hydrosodalite were primarily influenced by Na<sub>2</sub>O concentration and temperature. Both kaolinite dissolution and hydrosodalite precipitation were controlled by chemical reactions with activation energies of 70.152 (± 1.429) kJ/mol and 289.089 (± 2.063) kJ/mol, respectively, and the orders of reaction with respect to Na<sub>2</sub>O of 0.733 (± 0.070) and 7.165 (± 0.047), respectively. The kinetic equations describing kaolinite dissolution, hydrosodalite precipitation and even the leaching of SiO<sub>2</sub> were eventually modeled with Na<sub>2</sub>O concentration, temperature and time as variables.</p></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"260 ","pages":"Article 107537"},"PeriodicalIF":5.3,"publicationDate":"2024-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142049040","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Fast and efficient chromium(VI) extraction by colloidal Mg/Al layered double hydroxide nanoparticles","authors":"Abdelhak Fezraoui, Damien Cornu, Marc Hébrant","doi":"10.1016/j.clay.2024.107536","DOIUrl":"10.1016/j.clay.2024.107536","url":null,"abstract":"<div><p>Due to the constraints associated with diffusion and mixing time, traditional kinetic and thermodynamic approaches were inadequate for probing the true mechanism of interaction between chromate and Layered Double Hydroxide (LDH). To circumvent these limitations, colloidal suspensions of Mg/Al-NO<sub>3</sub> LDH, characterized by a positively charged surface (approximately +50 mV) in ultrapure water and a mean average diameter of 140 nm, allowing the formation of stable suspensions for days, were swiftly mixed with Cr(VI) suspensions at both pH = 4 and 9 using a stopped flow technique. This rapid mixing, accomplished in <5 milliseconds, enabled the examination of the initial stages of interaction between the toxic anion and the host compound. Two distinct steps in the adsorption process were identified: a very fast step (completed in <5 ms), representing up to 80% of the measured variation, and a slower step lasting up to 100 s. The fast step assumed to be driven by electrostatic interaction (ζ ∼ +50 mV) with the surface, and sites close to the surface are easily accessible to the chromate anions. The slower step corresponded to a diffusion process close or inside the particles. Chromate extraction efficiency was investigated through ultrafiltration tests, varying the LDH and chromate amounts, indicating that 2 nitrate ions are exchanged for 1 chromate, regardless of the pH considered, and a total exchange can be fulfilled with 0.1 g L<sup>−1</sup> of LDH within the explored concentration range.</p></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"260 ","pages":"Article 107536"},"PeriodicalIF":5.3,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142040922","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yun Li , Xuechi Liu , Meng Han , Zhouhua Wang , Ruixin Shi , Haoqi Liao , Bao Yuan , Pengfei Wang , Songbai Han , Jinlong Zhu
{"title":"Methane hydrate formation in amino acids / sodium montmorillonite systems","authors":"Yun Li , Xuechi Liu , Meng Han , Zhouhua Wang , Ruixin Shi , Haoqi Liao , Bao Yuan , Pengfei Wang , Songbai Han , Jinlong Zhu","doi":"10.1016/j.clay.2024.107538","DOIUrl":"10.1016/j.clay.2024.107538","url":null,"abstract":"<div><p>To understand the occurrence of natural gas hydrates in seabed sediments, it is crucial to examine the mechanisms of methane (CH<sub>4</sub>) hydrate formation in sodium montmorillonite (Na-Mt) systems in the presence of amino acid. Accordingly, this study employed kinetics experiments and molecular dynamics simulations to investigate CH<sub>4</sub> hydrate nucleation and growth in an <img>Na-Mt system containing alanine (Ala), leucine (Leu), and phenylalanine (Phe), respectively. Kinetics and Raman experiments showed that, compared with Ala, Leu and Phe enhanced hydrogen bonding between water molecules surrounding <img>Na-Mt. This enhancement was due to the long carbon chain of Leu and the phenyl ring of Phe and facilitated CH<sub>4</sub> hydrate formation. Moreover, in the <img>Na-Mt system, Ala reduced CH<sub>4</sub> consumption, whereas Leu and Phe increased CH<sub>4</sub> consumption. Molecular dynamics simulations revealed that the strength of electrostatic interactions between the negatively charged <img>Na-Mt surface and the functional groups of amino acids affected the distribution of amino acids, thereby altering CH<sub>4</sub> aggregation and CH<sub>4</sub> hydrate nucleation processes. The strong interaction between <img>Na-Mt and Ala significantly disrupted interfacial interactions between <img>Na-Mt and water molecules. In contrast, the weaker interactions between <img>Na-Mt and Leu and Phe, respectively, meant that these amino acids affected CH<sub>4</sub> hydrate nucleation in the bulk-like solution by influencing the arrangement of water molecules. These findings indicate that interfacial interactions between <img>Na-Mt and amino acids play a crucial role in CH<sub>4</sub> hydrate formation. Overall, this study generated insights into the formation kinetics and nucleation properties of CH<sub>4</sub> hydrates in clay mineral–amino acid complexes that may increase understanding about the occurrence of natural gas hydrates in marine sediments.</p></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"260 ","pages":"Article 107538"},"PeriodicalIF":5.3,"publicationDate":"2024-08-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142044424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Reza Taherdangkoo, Thomas Nagel, Chaofan Chen, Mostafa Mollaali, Mehran Ghasabeh, Olivier Cuisinier, Adel Abdallah, Christoph Butscher
{"title":"Modeling unsaturated hydraulic conductivity of compacted bentonite using a constrained CatBoost with bootstrap analysis","authors":"Reza Taherdangkoo, Thomas Nagel, Chaofan Chen, Mostafa Mollaali, Mehran Ghasabeh, Olivier Cuisinier, Adel Abdallah, Christoph Butscher","doi":"10.1016/j.clay.2024.107530","DOIUrl":"https://doi.org/10.1016/j.clay.2024.107530","url":null,"abstract":"Accurately determining the hydraulic conductivity of unsaturated bentonite is important for modeling subsurface thermo-hydro-mechanical and chemical processes. This study introduced a new hybrid model that employs a constrained categorial boosting (CatBoost) algorithm, combined with a genetic algorithm for hyperparameter tuning, to estimate the hydraulic conductivity of unsaturated compacted bentonite The performance of the constrained CatBoost model was benchmarked against a diverse set of data-driven baseline regression models, including lasso, elastic net, polynomial, k-nearest neighbors, decision tree, bagging tree, random forest, and CatBoost. The results indicated that the constrained CatBoost model offers a superior balance between model robustness and predictive accuracy in estimating the hydraulic conductivity of compacted bentonite-based materials during the wetting phase. The model effectively captured the U-shape relationship between hydraulic conductivity and suction, a key characteristic of bentonite behavior. Additionally, bootstrapping analyses confirmed the model's reliability under data variability, further validating its applicability in environmental and geotechnical applications.","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"49 1","pages":""},"PeriodicalIF":5.6,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142200034","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Peng-Ju Qin , Marsheal Fisonga , Yong-Feng Deng , Yu-Jun Cui , Wei-Min Ye
{"title":"Mechanical properties of teguline clay pellet mixtures during continuous oedometric compression","authors":"Peng-Ju Qin , Marsheal Fisonga , Yong-Feng Deng , Yu-Jun Cui , Wei-Min Ye","doi":"10.1016/j.clay.2024.107535","DOIUrl":"10.1016/j.clay.2024.107535","url":null,"abstract":"<div><p>Clay pellet mixtures are generally compressed to improve their engineering performance. Deepening the comprehension of the mechanical properties of these mixtures in the complete compression process facilitates the benefit to the engineering design and their utilization. In this study, the effects of soil grain size distribution, water content and dry density on the mechanical properties and microstructure of Teguline clay pellet mixtures during a continuous oedometric compression process are explored. Three types of soil pellet mixtures, including mixture A (grain size ≤5 mm), mixture B (≤ 0.4 mm) and mixture C (2–5 mm), were prepared with different water contents of 7%, 8% and 12% respectively. Subsequently, continuous oedometeric compression was undertaken to explore their mechanical behaviours of the soil pellet mixtures. After that, the microstropic structures of the compacted pellet mixtures were investigated using mercury intrusion porosimetry (MIP). The results indicated that mixture A has a minimal initial packing density of pellet mixtures, while mixture C has a maximum one at the initial compression stage. After completion of compression, the compression curves of the pellet mixtures tended to converge uniformity at a semilogarithm coordinate as the vertical stress increased. All of the compression curves presented a concave shape at the plastic compression stage, which is significantly influenced by grain size distribution and water content. In contrast, the elastic compression and rebound behaviours are little affected by the grain size distribution and water content. As far as the microstructure is concerned, compacted samples prepared by mixture A or C presented a unimodal pore structure, while those by mixture B showcased a bimodal pore structure. In comparison with the unimodal pore distribution of the undisturbed stiff clay, the compacted samples displayed a pseudo-unimodal pore distribution because the inter-aggregate pores still existed. A double tangent method was proposed to determine the delimiting pore diameter of the pseudo-unimodal pore distribution curves and found that the delimiting pore diameter decreased with the increase of dry density and water content. Moreover, the inflexion point for the pore diameter of compacted samples prepared by coarse soil was larger than that of fine soil. Combining this work with previous research, it was found that the high compression of coarse soil easily causes the pseudo-unimodal shape, which is also impacted by water content and particle properties. This work could help deepen the understanding of the mechanical characteristics and microstructure of the stiff clay pellet mixtures during continuous oedometric compression.</p></div>","PeriodicalId":245,"journal":{"name":"Applied Clay Science","volume":"260 ","pages":"Article 107535"},"PeriodicalIF":5.3,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142012555","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}