M. Ruiz-Linares, Vsevolod Fedoseev, C. Solana, Cecilia Muñoz-Sandoval, C. Ferrer-Luque
Background: Using endodontic sealers with long-term antimicrobial properties can increase the success of endodontic treatment. This study aimed to assess the antimicrobial activity over time of two calcium silicate (CS)-based sealers, AH Plus Bioceramic and BioRoot RCS, and to compare them with an epoxy resin-based sealer, AH Plus Jet, against mature polymicrobial biofilms grown on human radicular dentin. Methods: The antimicrobial activity of the sealers was tested using a direct contact test after 1 and 6 weeks of contact with the biofilms. Cell viability was determined by the adenosine triphosphate (ATP) method and flow cytometry (FC). The results of the ATP test were analyzed using an ANOVA with Welch’s correction, followed by the Games–Howell test. The number of cells with damaged membranes obtained by FC in each period was compared by means of an ANOVA and Duncan’s test. For the comparison between times, a Student’s t-test was used. Results: Globally, after a week of contact, the epoxy resin-based sealer obtained the best results. However, at 6 weeks, the two CSs showed the highest antimicrobial efficacy, with a significant increase in this activity over time. Conclusions: Calcium silicate-based sealers exert long-term antimicrobial activity against endodontic biofilms.
背景：使用具有长期抗菌特性的牙髓封闭剂可以提高牙髓治疗的成功率。本研究旨在评估两种基于硅酸钙（CS）的封闭剂（AH Plus Bioceramic 和 BioRoot RCS）的长期抗菌活性，并将它们与基于环氧树脂的封闭剂（AH Plus Jet）对生长在人类根尖牙本质上的成熟多微生物生物膜的抗菌活性进行比较。方法在与生物膜接触 1 周和 6 周后，采用直接接触测试法检测封闭剂的抗菌活性。细胞活力通过三磷酸腺苷（ATP）法和流式细胞仪（FC）测定。ATP 测试结果采用韦尔奇校正方差分析，然后进行 Games-Howell 检验。通过方差分析和邓肯检验比较了 FC 在每个时期获得的膜受损细胞的数量。时间间的比较采用学生 t 检验。结果总体而言，接触一周后，环氧树脂密封剂的效果最好。但是，在 6 周后，两种 CS 的抗菌效果最高，而且随着时间的推移，抗菌活性显著增强。结论基于硅酸钙的封闭剂对牙髓生物膜具有长期抗菌活性。
{"title":"Antibiofilm Efficacy of Calcium Silicate-Based Endodontic Sealers","authors":"M. Ruiz-Linares, Vsevolod Fedoseev, C. Solana, Cecilia Muñoz-Sandoval, C. Ferrer-Luque","doi":"10.3390/ma17163937","DOIUrl":"https://doi.org/10.3390/ma17163937","url":null,"abstract":"Background: Using endodontic sealers with long-term antimicrobial properties can increase the success of endodontic treatment. This study aimed to assess the antimicrobial activity over time of two calcium silicate (CS)-based sealers, AH Plus Bioceramic and BioRoot RCS, and to compare them with an epoxy resin-based sealer, AH Plus Jet, against mature polymicrobial biofilms grown on human radicular dentin. Methods: The antimicrobial activity of the sealers was tested using a direct contact test after 1 and 6 weeks of contact with the biofilms. Cell viability was determined by the adenosine triphosphate (ATP) method and flow cytometry (FC). The results of the ATP test were analyzed using an ANOVA with Welch’s correction, followed by the Games–Howell test. The number of cells with damaged membranes obtained by FC in each period was compared by means of an ANOVA and Duncan’s test. For the comparison between times, a Student’s t-test was used. Results: Globally, after a week of contact, the epoxy resin-based sealer obtained the best results. However, at 6 weeks, the two CSs showed the highest antimicrobial efficacy, with a significant increase in this activity over time. Conclusions: Calcium silicate-based sealers exert long-term antimicrobial activity against endodontic biofilms.","PeriodicalId":503043,"journal":{"name":"Materials","volume":"18 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141926909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The phenomenon of rate-dependent adhesion has long been recognized as an intricate problem, and the so-far-developed physics and mechanics-based approaches resulted in analytical relations between the implicit form between the work of adhesion and the contact front velocity which are difficult to implement in practice. To address this issue in the framework of spherical indentation, the adhesion relaxation test in a nominal point contact is introduced to estimate the rate-dependent adhesion. Based on a stretched exponent approximation for the contact radius evolution with time, a relatively simple four-parameter model is proposed for the functional relation between the work of adhesion and the contact front velocity, and its fitting performance is compared to that of the known Greenwood–Johnson and Persson–Brener models.
{"title":"Ad Hoc Modeling of Rate-Dependent Adhesion in Indentation Relaxation Testing","authors":"I. Argatov, I. Lyashenko, V. L. Popov","doi":"10.3390/ma17163944","DOIUrl":"https://doi.org/10.3390/ma17163944","url":null,"abstract":"The phenomenon of rate-dependent adhesion has long been recognized as an intricate problem, and the so-far-developed physics and mechanics-based approaches resulted in analytical relations between the implicit form between the work of adhesion and the contact front velocity which are difficult to implement in practice. To address this issue in the framework of spherical indentation, the adhesion relaxation test in a nominal point contact is introduced to estimate the rate-dependent adhesion. Based on a stretched exponent approximation for the contact radius evolution with time, a relatively simple four-parameter model is proposed for the functional relation between the work of adhesion and the contact front velocity, and its fitting performance is compared to that of the known Greenwood–Johnson and Persson–Brener models.","PeriodicalId":503043,"journal":{"name":"Materials","volume":"16 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141926025","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Hundreds of nanometer-thick metal layers are used as electrical conductors in various technologies and research fields. The intensity of the radiation transmitted by such devices is a small fraction and is often neglected. Here, it is shown that intense terahertz time-domain spectroscopy can probe the absolute electro-optical properties of a 100 nm thick gold sample in transmission geometry without the need to apply electrical contacts or handle wires. The terahertz conductivity of the metal film agrees with that obtained from standard contact measurements of the static component within the error bars. This experimental approach can help to quantify the electrical properties of opaque and conductive materials such as the composite electrodes used in photovoltaic or electrochemical applications, and in the quality control of metal films.
{"title":"Terahertz Transmission through a Gold Mirror or Electrode","authors":"F. Novelli","doi":"10.3390/ma17163942","DOIUrl":"https://doi.org/10.3390/ma17163942","url":null,"abstract":"Hundreds of nanometer-thick metal layers are used as electrical conductors in various technologies and research fields. The intensity of the radiation transmitted by such devices is a small fraction and is often neglected. Here, it is shown that intense terahertz time-domain spectroscopy can probe the absolute electro-optical properties of a 100 nm thick gold sample in transmission geometry without the need to apply electrical contacts or handle wires. The terahertz conductivity of the metal film agrees with that obtained from standard contact measurements of the static component within the error bars. This experimental approach can help to quantify the electrical properties of opaque and conductive materials such as the composite electrodes used in photovoltaic or electrochemical applications, and in the quality control of metal films.","PeriodicalId":503043,"journal":{"name":"Materials","volume":"43 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141929669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
To address the challenges of slow curing speed and suboptimal microwave absorption during the paving of cold-mixed and cold-laid asphalt mixtures, this study introduces SiC-Fe3O4 composite material (SF) into emulsified asphalt mixtures to enhance microwave absorption and accelerate curing via microwave heating. Initially, based on the maximum density curve theory, an appropriate mineral aggregate gradation was designed, and the optimal ratio of emulsified asphalt mixture was determined through mixing tests, cohesion tests, wet wheel wear tests, and load wheel sand adhesion tests. Subsequently, the influence of SF content on the mixing performance of emulsified asphalt mixtures was analyzed through mixing and consistency tests. Finally, the microwave absorption performance of the mixture was evaluated by designing microwave heating tests under different conditions, using temperature indicators and quality indicators. The experimental results indicate that when SF content ranges from 0% to 4%, the mixing performance of the emulsified asphalt mixture meets specification requirements. The dosage of SF, SF composite ratio, and microwave power significantly impact microwave absorption performance, whereas environmental temperature has a relatively minor effect. The optimal mix ratio for the emulsified asphalt mixture is mineral aggregate:modified emulsified asphalt:water:cement = 100:12.8:6:1. The ideal SF dosage is 4%, with an optimal SiC to Fe3O4 composite ratio of 1:1, and a suitable microwave power range of 600–1000 W.
为解决冷拌和冷铺沥青混合料摊铺过程中固化速度慢和微波吸收不理想的难题，本研究在乳化沥青混合料中引入 SiC-Fe3O4 复合材料（SF），通过微波加热增强微波吸收并加速固化。首先，根据最大密度曲线理论，设计了合适的矿料级配，并通过拌和试验、粘聚试验、湿轮磨损试验和荷载轮砂粘附试验，确定了乳化沥青混合料的最佳配比。随后，通过拌和试验和稠度试验分析了 SF 含量对乳化沥青混合料拌和性能的影响。最后，通过设计不同条件下的微波加热试验，利用温度指标和质量指标评估了混合料的微波吸收性能。实验结果表明，当 SF 含量在 0% 至 4% 之间时，乳化沥青混合料的搅拌性能符合规范要求。SF用量、SF复合比例和微波功率对微波吸收性能有显著影响，而环境温度的影响相对较小。乳化沥青混合料的最佳混合比为矿物集料:改性乳化沥青:水:水泥=100:12.8:6:1。理想的 SF 用量为 4%，SiC 与 Fe3O4 的最佳复合比例为 1:1，合适的微波功率范围为 600-1000 W。
{"title":"Design and Microwave Absorption Performance Study of SiC-Fe3O4 Emulsified Asphalt Mixture","authors":"Xiangyu Jiang, Wen Xu, Yixing Chen, Jiaqi Li","doi":"10.3390/ma17163935","DOIUrl":"https://doi.org/10.3390/ma17163935","url":null,"abstract":"To address the challenges of slow curing speed and suboptimal microwave absorption during the paving of cold-mixed and cold-laid asphalt mixtures, this study introduces SiC-Fe3O4 composite material (SF) into emulsified asphalt mixtures to enhance microwave absorption and accelerate curing via microwave heating. Initially, based on the maximum density curve theory, an appropriate mineral aggregate gradation was designed, and the optimal ratio of emulsified asphalt mixture was determined through mixing tests, cohesion tests, wet wheel wear tests, and load wheel sand adhesion tests. Subsequently, the influence of SF content on the mixing performance of emulsified asphalt mixtures was analyzed through mixing and consistency tests. Finally, the microwave absorption performance of the mixture was evaluated by designing microwave heating tests under different conditions, using temperature indicators and quality indicators. The experimental results indicate that when SF content ranges from 0% to 4%, the mixing performance of the emulsified asphalt mixture meets specification requirements. The dosage of SF, SF composite ratio, and microwave power significantly impact microwave absorption performance, whereas environmental temperature has a relatively minor effect. The optimal mix ratio for the emulsified asphalt mixture is mineral aggregate:modified emulsified asphalt:water:cement = 100:12.8:6:1. The ideal SF dosage is 4%, with an optimal SiC to Fe3O4 composite ratio of 1:1, and a suitable microwave power range of 600–1000 W.","PeriodicalId":503043,"journal":{"name":"Materials","volume":"18 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141925570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Milica Išljamović, D. Bonvin, Milena Milojević, Simona Stojanović, M. Spasić, B. Stojković, P. Janošević, Suzana A Otasevic, M. M. Ebersold
The control of Candida albicans biofilm formation on dentures made of poly(methyl methacrylate) (PMMA) is an important challenge due to the high resistance to antifungal drugs. Interestingly, the natural compounds undecylenic acid (UDA) and farnesol (FAR) both prevent C. albicans biofilm formation and could have a synergetic effect. We therefore modified PMMA with a combination of UDA and FAR (UDA+FAR), aiming to obtain the antifungal PMMA_UDA+FAR composites. Equal concentrations of FAR and UDA were added to PMMA to reach 3%, 6%, and 9% in total of both compounds in composites. The physico-chemical properties of the composites were characterized by Fourier-transform infrared spectroscopy and water contact angle measurement. The antifungal activity of the composites was tested on both biofilm and planktonic cells with an XTT test 0 and 6 days after the composites’ preparation. The effect of the UDA+FAR combination on C. albicans filamentation was studied in agar containing 0.0125% and 0.4% UDA+FAR after 24 h and 48 h of incubation. The results showed the presence of UDA and FAR on the composite and decreases in the water contact angle and metabolic activity of both the biofilm and planktonic cells at both time points at non-toxic UDA+FAR concentrations. Thus, the modification of PMMA with a combination of UDA+FAR reduces C. albicans biofilm formation on dentures and could be a promising anti-Candida strategy.
{"title":"Antifungal Effect of Poly(methyl methacrylate) with Farnesol and Undecylenic Acid against Candida albicans Biofilm Formation","authors":"Milica Išljamović, D. Bonvin, Milena Milojević, Simona Stojanović, M. Spasić, B. Stojković, P. Janošević, Suzana A Otasevic, M. M. Ebersold","doi":"10.3390/ma17163936","DOIUrl":"https://doi.org/10.3390/ma17163936","url":null,"abstract":"The control of Candida albicans biofilm formation on dentures made of poly(methyl methacrylate) (PMMA) is an important challenge due to the high resistance to antifungal drugs. Interestingly, the natural compounds undecylenic acid (UDA) and farnesol (FAR) both prevent C. albicans biofilm formation and could have a synergetic effect. We therefore modified PMMA with a combination of UDA and FAR (UDA+FAR), aiming to obtain the antifungal PMMA_UDA+FAR composites. Equal concentrations of FAR and UDA were added to PMMA to reach 3%, 6%, and 9% in total of both compounds in composites. The physico-chemical properties of the composites were characterized by Fourier-transform infrared spectroscopy and water contact angle measurement. The antifungal activity of the composites was tested on both biofilm and planktonic cells with an XTT test 0 and 6 days after the composites’ preparation. The effect of the UDA+FAR combination on C. albicans filamentation was studied in agar containing 0.0125% and 0.4% UDA+FAR after 24 h and 48 h of incubation. The results showed the presence of UDA and FAR on the composite and decreases in the water contact angle and metabolic activity of both the biofilm and planktonic cells at both time points at non-toxic UDA+FAR concentrations. Thus, the modification of PMMA with a combination of UDA+FAR reduces C. albicans biofilm formation on dentures and could be a promising anti-Candida strategy.","PeriodicalId":503043,"journal":{"name":"Materials","volume":"25 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141927220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The rapid development of new energy vehicles demands significant improvements in connector structures and performance standards. Wire harness connectors, crucial for linking various electrical components, face challenges due to their small size and thin-walled structure, which can lead to dimensional shrinkage and warping during injection molding. To address these issues, this study optimizes the injection molding process by fine-tuning parameters such as melt temperature, mold temperature, injection time, holding pressure/time, and cooling time. By integrating the Taguchi method with grey relational analysis, the study enhances the molding process for thin-walled composite connectors. This combined approach provides a comprehensive framework for optimizing multiple quality objectives and improving the overall performance of injection-molded composite components.
{"title":"Multi-Objective Optimization of Injection Molding Parameters for Manufacturing Thin-Walled Composite Connector Terminals","authors":"Mingbo Tan, Size Peng, Yingfei Huo, Maojun Li","doi":"10.3390/ma17163949","DOIUrl":"https://doi.org/10.3390/ma17163949","url":null,"abstract":"The rapid development of new energy vehicles demands significant improvements in connector structures and performance standards. Wire harness connectors, crucial for linking various electrical components, face challenges due to their small size and thin-walled structure, which can lead to dimensional shrinkage and warping during injection molding. To address these issues, this study optimizes the injection molding process by fine-tuning parameters such as melt temperature, mold temperature, injection time, holding pressure/time, and cooling time. By integrating the Taguchi method with grey relational analysis, the study enhances the molding process for thin-walled composite connectors. This combined approach provides a comprehensive framework for optimizing multiple quality objectives and improving the overall performance of injection-molded composite components.","PeriodicalId":503043,"journal":{"name":"Materials","volume":"17 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141926290","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Boyu Pan, F. Shen, Sanjay Raghav Sampathkumar, Sebastian Münstermann
This study uses a sigmoidal function to describe the plastic strain hardening of metallic materials, considering temperature and strain rate effects. The effectiveness of this approach is evaluated and systematically compared with other hardening laws. Incorporating temperature and strain rate effects into the parameters of this sigmoidal-type hardening law enables a more precise description and prediction of the plastic deformation of materials under different combinations of temperature and strain rate. The temperature effect is coupled using a simplified Arrhenius model, and the strain rate effect is coupled with a modified Johnson–Cook model. The sigmoidal-type hardening law is integrated with an asymmetric yield criterion to address complex behavior, such as anisotropy and strength differential effects. The calibration and validation of the constitutive model involve examining uniaxial tensile/compressive flow curves in various directions and biaxial tensile/compressive flow curves for diverse metallic alloys, proving the proposed model’s broad applicability.
{"title":"Modeling Strain Hardening of Metallic Materials with Sigmoidal Function Considering Temperature and Strain Rate Effects","authors":"Boyu Pan, F. Shen, Sanjay Raghav Sampathkumar, Sebastian Münstermann","doi":"10.3390/ma17163950","DOIUrl":"https://doi.org/10.3390/ma17163950","url":null,"abstract":"This study uses a sigmoidal function to describe the plastic strain hardening of metallic materials, considering temperature and strain rate effects. The effectiveness of this approach is evaluated and systematically compared with other hardening laws. Incorporating temperature and strain rate effects into the parameters of this sigmoidal-type hardening law enables a more precise description and prediction of the plastic deformation of materials under different combinations of temperature and strain rate. The temperature effect is coupled using a simplified Arrhenius model, and the strain rate effect is coupled with a modified Johnson–Cook model. The sigmoidal-type hardening law is integrated with an asymmetric yield criterion to address complex behavior, such as anisotropy and strength differential effects. The calibration and validation of the constitutive model involve examining uniaxial tensile/compressive flow curves in various directions and biaxial tensile/compressive flow curves for diverse metallic alloys, proving the proposed model’s broad applicability.","PeriodicalId":503043,"journal":{"name":"Materials","volume":"25 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141928715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mixing cement with seawater will cause the hydration process of cement to be different from that of ordinary cement, which will significantly affect cement’s mechanical properties and durability. This article investigates the effects of chloride ion concentration, curing temperature, and nano-metakaolin content on the evolution process of Friedel’s salts and ettringite (AFt) crystals in cement pastes. The study was conducted using X-ray diffraction (XRD), thermal analysis (TG), scanning electron microscopy (SEM), and mercury-intrusion porosimetry (MIP). The results show that chlorine salt can increase the production of Friedel’s salt and ettringite, and the delayed AFt production increases by up to 27.95% after the addition of chlorine salt, which has an adverse effect on cement-based materials. Increasing the curing temperature and increasing the nano-metakaolin dosage increased the generation of Friedel’s salt and decreased the delayed AFt generation, which resulted in a decrease in the length and diameter of the AFt crystals. After 28 days of high-temperature curing and the addition of nano-metakaolin, Friedel’s salt production increased by 13.40% and 14.34%, respectively, and ettringite production decreased by 9.68% and 7.93%, respectively. Increasing the curing temperature and adding nano-metakaolin can reduce the adverse effect of delayed ettringite increases due to chloride ion binding.
{"title":"Study on the Binding Behavior of Chloride Ion and Ettringite in Nano-Metakaolin Cement by Seawater Mixing and Curing Temperatures","authors":"Zhisheng Fang, Shiyi Zhang, Wenjie Qi, Yingfang Fan, Surendra P. Shah, Junjie Zheng","doi":"10.3390/ma17163943","DOIUrl":"https://doi.org/10.3390/ma17163943","url":null,"abstract":"Mixing cement with seawater will cause the hydration process of cement to be different from that of ordinary cement, which will significantly affect cement’s mechanical properties and durability. This article investigates the effects of chloride ion concentration, curing temperature, and nano-metakaolin content on the evolution process of Friedel’s salts and ettringite (AFt) crystals in cement pastes. The study was conducted using X-ray diffraction (XRD), thermal analysis (TG), scanning electron microscopy (SEM), and mercury-intrusion porosimetry (MIP). The results show that chlorine salt can increase the production of Friedel’s salt and ettringite, and the delayed AFt production increases by up to 27.95% after the addition of chlorine salt, which has an adverse effect on cement-based materials. Increasing the curing temperature and increasing the nano-metakaolin dosage increased the generation of Friedel’s salt and decreased the delayed AFt generation, which resulted in a decrease in the length and diameter of the AFt crystals. After 28 days of high-temperature curing and the addition of nano-metakaolin, Friedel’s salt production increased by 13.40% and 14.34%, respectively, and ettringite production decreased by 9.68% and 7.93%, respectively. Increasing the curing temperature and adding nano-metakaolin can reduce the adverse effect of delayed ettringite increases due to chloride ion binding.","PeriodicalId":503043,"journal":{"name":"Materials","volume":"46 9","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141929622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Aeolian sand is distributed worldwide, exhibiting poor grading, low cohesion, and loose structure. Infrastructure construction in desert areas sometimes requires stabilization of the sand, with cement as the primary curing agent. This study first employed orthogonal experiments to evaluate critical factors, e.g., curing time, cement dosage, and water dosage, affecting the unconfined compressive strength (UCS) of the aeolian sand stabilized with cement (ASC). Each of the aforementioned factors were set at five levels, namely curing time (7, 14, 28, 60, and 90 days), cement dosage (3%, 5%, 7%, 9%, and 11%), and water dosage (3%, 6%, 9%, 12%, and 15%), respectively. The water and cement dosages were percentages of the mass of the natural aeolian sand. The results indicated that the sensitivity of the influencing factors on the UCS of ASC was cement dosage, curing time, and water dosage in descending order. The UCS of ASC positively correlated with curing time and cement dosage, while it first increased and then decreased with the water dosage increase. The optimal conditions were 90 days’ curing time, 11% cement dosage, and 9% water dosage. The microscopic analyses of ASC using optical microscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) revealed that hydration products enhanced strength by bonding loose particles and filling pores, thereby improving compaction. The quantity and compactness of hydration products in the aeolian–cement reaction system increased with the increases in cement dosage and curing time, and low water dosage inhibited the hydration reaction. This study can provide insights into the stabilization mechanism of aeolian sand, aiding infrastructure development in desert regions.
{"title":"Effects of Cement Dosage, Curing Time, and Water Dosage on the Strength of Cement-Stabilized Aeolian Sand Based on Macroscopic and Microscopic Tests","authors":"Heng Yang, Zengzhen Qian, Bing Yue, Zilu Xie","doi":"10.3390/ma17163946","DOIUrl":"https://doi.org/10.3390/ma17163946","url":null,"abstract":"Aeolian sand is distributed worldwide, exhibiting poor grading, low cohesion, and loose structure. Infrastructure construction in desert areas sometimes requires stabilization of the sand, with cement as the primary curing agent. This study first employed orthogonal experiments to evaluate critical factors, e.g., curing time, cement dosage, and water dosage, affecting the unconfined compressive strength (UCS) of the aeolian sand stabilized with cement (ASC). Each of the aforementioned factors were set at five levels, namely curing time (7, 14, 28, 60, and 90 days), cement dosage (3%, 5%, 7%, 9%, and 11%), and water dosage (3%, 6%, 9%, 12%, and 15%), respectively. The water and cement dosages were percentages of the mass of the natural aeolian sand. The results indicated that the sensitivity of the influencing factors on the UCS of ASC was cement dosage, curing time, and water dosage in descending order. The UCS of ASC positively correlated with curing time and cement dosage, while it first increased and then decreased with the water dosage increase. The optimal conditions were 90 days’ curing time, 11% cement dosage, and 9% water dosage. The microscopic analyses of ASC using optical microscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD) revealed that hydration products enhanced strength by bonding loose particles and filling pores, thereby improving compaction. The quantity and compactness of hydration products in the aeolian–cement reaction system increased with the increases in cement dosage and curing time, and low water dosage inhibited the hydration reaction. This study can provide insights into the stabilization mechanism of aeolian sand, aiding infrastructure development in desert regions.","PeriodicalId":503043,"journal":{"name":"Materials","volume":"44 13","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141929649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study introduces a novel method for particle abrasion derived from fundamental natural phenomena and mechanical principles, allowing precise control over the degree of abrasion and more accurately mimicking natural processes. The method’s validity is confirmed using a specific shape index. Through conventional triaxial tests, the mechanical behavior of granular aggregates with varying degrees of abrasion was analyzed. The findings indicate that increased particle abrasion leads to a decrease in the average coordination number and sliding amount, while the rotation amount increases. This suggests an inverse relationship between the degree of abrasion and the structural stability and interlocking of the particle aggregate. The fabric anisotropy of the system is mainly attributed to the anisotropy of the contact normal force, which decreases as particle abrasion increases. The partial stress ratio of the particle system is influenced by fabric anisotropy and remains independent of particle shape. Additionally, the internal friction angle may be overestimated in conventional triaxial tests.
{"title":"Modeling of the Particle Abrasion Process and a Discrete Element Method Study of Its Shape Effect","authors":"Zhengbo Hu, Junhui Zhang, Xin Tan, Hao Yang","doi":"10.3390/ma17163947","DOIUrl":"https://doi.org/10.3390/ma17163947","url":null,"abstract":"This study introduces a novel method for particle abrasion derived from fundamental natural phenomena and mechanical principles, allowing precise control over the degree of abrasion and more accurately mimicking natural processes. The method’s validity is confirmed using a specific shape index. Through conventional triaxial tests, the mechanical behavior of granular aggregates with varying degrees of abrasion was analyzed. The findings indicate that increased particle abrasion leads to a decrease in the average coordination number and sliding amount, while the rotation amount increases. This suggests an inverse relationship between the degree of abrasion and the structural stability and interlocking of the particle aggregate. The fabric anisotropy of the system is mainly attributed to the anisotropy of the contact normal force, which decreases as particle abrasion increases. The partial stress ratio of the particle system is influenced by fabric anisotropy and remains independent of particle shape. Additionally, the internal friction angle may be overestimated in conventional triaxial tests.","PeriodicalId":503043,"journal":{"name":"Materials","volume":"51 26","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141929703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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