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Influence of Cement Matrix Composition and Fiber Geometric Properties on the High-Temperature Resistance of the Ultra High-Performance Concrete (Uhpc)

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SSRN 2023年

作者： Ma, Wenbo Yang, Ke Deng, Peng Zhang, Chao Chen, Renpeng Guo, Shuaicheng School of Mechanical Engineering and Mechanics Xiangtan University Xiangtan411105 China College of Civil Engineering Xiangtan University Xiangtan411105 China Key Laboratory of Building Safety and Energy Efficiency of the Ministry of Education Hunan University Changsha410082 China International Science Innovation Collaboration Base for Green & Advanced Civil Engineering Materials of Hunan Province Hunan University Changsha410082 China Key Laboratory for Green & Advanced Civil Engineering Materials and Application Technology of Hunan Province College of Civil Engineering Hunan University Changsha410082 China

Ultra High-Performance Concrete (UHPC) owns a broad application prospect in engineering construction due to its superior mechanical and durability performance. However, the inappropriate high-temperature resistance of UHPC due to its densified internal structure restricts its application in structural engineering and underground construction. This study aims to investigate the influence of cement matrix composition and fiber geometric properties on the high-temperature resistance of the UHPC. The UHPC is designed and prepared with the Cement-FA-SF cement matrix and steel fiber. Polypropylene fibers with different diameters and lengths are incorporated to enhance the high-temperature resistance. The high-temperature resistance is characterized by measuring the changes in compressive strength and flexural and tensile strength after high-temperature exposure. It is found that the high-temperature resistance of UHPC first increases and then decreases with the FA content. Meanwhile the resistance generally decreases with the SF content, and the influence of cement content on the resistance is not obvious. It is further indicated that the high-temperature resistance of UHPC first increases and then decreases with the length of the incorporated Polypropylene fiber. Meanwhile, the influence of Polypropylene fiber diameter on the high-temperature resistance changes with its diameter. The influence of high-temperature exposure on the fracture toughness of UHPC is characterized by the Crack Mouth Opening Displacement (CMOD) test. It is found that exposure to high-temperature can reduce the fracture toughness, depth of the propagated crack, energy consumption and ductility of the UHPC materials. This study can serve as a solid base to enhance the high-temperature resistance of the UHPC materials and broaden its application. © 2023, The Authors. All rights reserved.

关键词： Fracture toughness

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Design and Characterization of Low-Carbon Supersulfated Cement Prepared Using As-Received Electrolysis Manganese Dioxide Residue

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SSRN 2023年

作者： Ma, Wenbo Bai, Tianwen Zhu, Wei Guo, Shuaicheng School of Mechanical Engineering and Mechanics Xiangtan University Xiangtan411105 China College of Civil Engineering Xiangtan University Xiangtan411105 China Hunan Key Laboratory for Computation and Simulation in Science and Engineering Xiangtan University Xiangtan411105 China Key Laboratory of Building Safety and Energy Efficiency of the Ministry of Education Hunan University Changsha410082 China International Science Innovation Collaboration Base for Green & Advanced Civil Engineering Materials of Hunan Province Hunan University Changsha410082 China Key Laboratory for Green & Advanced Civil Engineering Materials and Application Technology of Hunan Province College of Civil Engineering Hunan University Changsha410082 China

Utilizing electrolysis manganese dioxide residue (EMDR) to prepare the supersulfated cement can achieve effective waste recycling, and its application can reduce the carbon emission caused by Portland cement. This study aims to quantitatively build the correlation between the mechanical performance and cementitious matrix composition of EMDR-based supersulfated cement. The supersulfated cement containing clinker, slag and as received EMDR is designed and prepared based on the simplex centroid design method. The compressive strength, tensile strength and flexural strength of the EMDR based supersulfated cement paste were measured at 3-day, 7-day and 28-day ages. The compressive strength of the electrolysis manganese dioxide residue (EMDR) based supersulfated cement first increases and then decreases with the mass ratio between slag and EMDR. The added cement clinker can increase the compressive strength at 3-day and 7-day ages, but the 28-day age strength first decrease and then increase with the cement clinker content. Meanwhile, the flexural and tensile performances of the EMDR based supersulfated cement generally increase with the clinker content. The measured elastic modulus results indicated the added clinker could enhance the stiffness of the stiffness development. Then the strength development mechanisms of EMDR-based supersulfated cement are analyzed based on phase and microstructure characterization. It is found the clinker can accelerate the reaction rate between the slag and EMDR, and the consumption rate of the gypsum contained in EMDR. The calcium silicate hydrate (CSH) gel phase's contribution to tensile strength is more significant than that of ettringite phase. Based on the mechanism analysis, the index of [SO3]/[Al2O3] molar ratio is proposed for the matrix design of EMDR based SSC. This study can support the design and application of EMDR-based supersulfated cement. © 2023, The Authors. All rights reserved.

关键词： Aluminum oxide

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Thickness-dependent atomic structures of two-dimensional few-layer ZnO: A density functional theory study

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Physical Review B 2024年第1期109卷 014105-014105页

作者： Dong Han Xian-Bin Li Nian-Ke Chen Dan Wang Sheng-Yi Xie Xue-Jiao Chen De-Zhen Shen State Key Laboratory of Luminescence and Applications Changchun Institute of Optics Fine Mechanics and Physics Chinese Academy of Sciences Changchun 130033 People's Republic of China State Key Laboratory of Integrated Optoelectronics College of Electronic Science and Engineering Jilin University Changchun 130012 People's Republic of China School of Materials Science and Engineering Beijing Institute of Technology Beijing 100081 People's Republic of China School of Physics and Electronics Hunan University Changsha 410082 People's Republic of China CAS Key Laboratory of Magnetic Materials Devices and Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Ningbo 315201 People's Republic of China

The thickness-dependent atomic structures of two-dimensional (2D) few-layer (FL) ZnO are systematically investigated by the first-principles calculations. It is found that the structural transformation between thinner FL ZnO with graphitic structure (FL gZnO) and thicker FL ZnO with wurtzite structure (FL wZnO) takes place at the critical thickness of 9–12 Zn-O atomic layers. At the thickness of 9–12 layers, both graphitic and wurtzite structures can coexist at room temperature. In FL gZnO, the interlayer interaction is a long-range Coulomb interaction, and the charge population of Zn and O inside does not change during the structural transformation. Moreover, we demonstrate that the structural transformation of FL ZnO originates from the competition between the high energy of the O 2pz orbital in the graphitic structure and the polar-surface-induced dipole energy in the wurtzite structure. Our microscopic understanding guides a clear direction of regulating the atomic structure of FL ZnO, further optimizing its electronic properties, which benefits developing function-advanced 2D stacked devices.

关键词： Crystal structure II-VI semiconductors Multilayer thin films Density functional calculations

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PVPUFormer: Probabilistic Visual Prompt Unified Transformer for Interactive Image Segmentation

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arXiv 2023年

作者： Zhang, Xu Yang, Kailun Lin, Jiacheng Yuan, Jin Li, Zhiyong Li, Shutao College of Computer Science and Electronic Engineering Hunan University Changsha410082 China School of Robotics The National Engineering Research Center of Robot Visual Perception and Control Technology Hunan University Changsha410082 China College of Electrical and Information Engineering The Key Laboratory of Visual Perception and Artificial Intelligence of Hunan Province Hunan University Changsha410082 China

Integration of diverse visual prompts like clicks, scribbles, and boxes in interactive image segmentation significantly facilitates users’ interaction as well as improves interaction efficiency. However, existing studies primarily encode the position or pixel regions of prompts without considering the contextual areas around them, resulting in insufficient prompt feedback, which is not conducive to performance acceleration. To tackle this problem, this paper proposes a simple yet effective Probabilistic Visual Prompt Unified Transformer (PVPUFormer) for interactive image segmentation, which allows users to flexibly input diverse visual prompts with the probabilistic prompt encoding and feature post-processing to excavate sufficient and robust prompt features for performance boosting. Specifically, we first propose a Probabilistic Prompt-unified Encoder (PPuE) to generate a unified one-dimensional vector by exploring both prompt and non-prompt contextual information, offering richer feedback cues to accelerate performance improvement. On this basis, we further present a Prompt-to-Pixel Contrastive (P2C) loss to accurately align both prompt and pixel features, bridging the representation gap between them to offer consistent feature representations for mask prediction. Moreover, our approach designs a Dual-cross Merging Attention (DMA) module to implement bidirectional feature interaction between image and prompt features, generating notable features for performance improvement. A comprehensive variety of experiments on several challenging datasets demonstrates that the proposed components achieve consistent improvements, yielding state-of-the-art interactive segmentation performance. Our code is available at https://***/XuZhang1211/PVPUFormer. Copyright © 2023, The Authors. All rights reserved.

关键词： Pixels

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Corrosion Mechanism of Cement-Fly Ash-Slag Ternary Mortars Under Carbonic Acid Water Containing Chloride Ions

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SSRN 2024年

作者： Zhang, Shuqing Liu, Jianhui Wei, Junfeng Liu, Leping Chen, Zheng Shi, Caijun Key Laboratory of Disaster Prevention and Structural Safety of China Ministry of Education School of Civil Engineering and Architecture Guangxi University Nanning530004 China State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures Guangxi University Nanning530004 China College of Chemistry and Materials Nanning Normal University Nanning530100 China Key Laboratory for Green & Advanced Civil Engineering Materials and Application Technology of Hunan Province College of Civil Engineering Hunan University Changsha410082 China

This study investigated the corrosion behavior of cement-fly ash-slag ternary mortars under carbonic acid water containing chloride ions and the impact of carbonic acid water corrosion on the redistribution of chloride ions in the mortars. Test results indicated that the pozzolanic reaction of slag significantly reduced compressive strength loss and the corrosion depth. The fly ash, in contrast, with inadequate activity, thereby failing to effectively enhance the mortar's resistance against carbonic acid water corrosion. Additionally, carbonic acid water corrosion promoted the decomposition of Friedel's salt, reducing the chloride ions binding capacity of the mortars. The precipitation and dissolution of calcium carbonate initially decreased and then increased the diffusion rate of free chloride ions. The interaction mechanisms between carbonic acid water corrosion and chloride ion penetration are demonstrated by chloride ions diffusion, low field NMR and mineral composition analysis. © 2024, The Authors. All rights reserved.

关键词： Mortar

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Building national eco-cultural protection areas and the Xiangxi practice in hunan province

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Journal of Geographical Sciences 2020年第12期30卷 2076-2092页

作者： LIU Chunla WU Liping XU Mei ZENG Fanchao JIAO Lipeng College of Resources and Environment Sciences Hunan Normal UniversityChangsha 410081China Key Laboratory of Geospatial Big Data Mining and Application Hunan ProvinceChangsha 410081China College of Tourism Central South University of Forestry and TechnologyChangsha 410004China

Since 2007,the Chinese government has initiated the building of national eco-cultural protection areas(NECPAs),thereby embarking on a significant transformation of the model of intangible cultural heritage(IC H)protection in *** understand the origin and outputs of this policy,this paper demonstrates the context of China's *** proposes a conceptual NECPA framework that mainly features regional overall ICH *** is followed by an examination of the case of Xiangxi in Western hunan as a pilot zone for China’s eco-cultural *** has performed much related work to promote NECPAs and made great progress in regional overall ICH *** insight suggests that there are benefits and costs associated with promotion of China's NECPAs and regional overall ICH *** the advantages of institutional innovation,the unexpected side effects actually undermine the success of plan implementation.

关键词： national eco-cultural protection area intangible cultural heritage regional overall protection Xiangxi China

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Study on the Corrosion of Portland Cement-Fly Ash-Slag Ternary Mortars In Carbonic Acid Water With Chloride Ions

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SSRN 2024年

作者： Liu, Leping Zhang, Shuqing Wei, Junfeng Chen, Zheng Shi, Caijun Liu, Jianhui Key Laboratory of Disaster Prevention and Structural Safety of China Ministry of Education School of Civil Engineering and Architecture Guangxi University Nanning530004 China State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures Guangxi University Nanning530004 China College of Chemistry and Materials Nanning Normal University Nanning530100 China Key Laboratory for Green & Advanced Civil Engineering Materials and Application Technology of Hunan Province College of Civil Engineering Hunan University Changsha410082 China

In this paper, the effect of slag and fly ash on the corrosion process of cement mortars by carbonic acid water with chloride ions and the interaction between carbonic acid water and chloride ions were studied. The changes of mineral composition and pore structure of ternary mortars caused by corrosion were analyzed. The influence of chloride ions permeability in carbonic acid water was discussed. The results showed that the corrosion of carbonic acid water with chloride ions can be divided into three stages: CaCO3 precipitation stage, chloride binding stage and calcium leaching with chloride-debinding stage. The addition of slag delays the corrosion of carbonic acid water. It also decreases the penetration depth of free chloride ions and enhances their binding capability. On the other hand, the addition of fly ash promotes the corrosion caused by carbonic acid water. While fly ash improved chloride ions-binding capability in a single chloride ions environment due to slow secondary hydration reaction, this effect is inhibited in carbonic acid water. Furthermore, there is an interaction between carbonic acid water and chloride ions. The refined pore structure created by Friedel's salt delayed carbonic acid corrosion;however, it decomposes when calcium hydroxide was consumed under carbonic acid conditions which leads to release of free chloride ions. The formation of a calcium carbonate layer hindered external chloride ion diffusion initially but promoted the diffusion upon dissolution during the stage where calcium leaches out. © 2024, The Authors. All rights reserved.

关键词： Fly ash

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Research on the Source-Load Interactive Scheduling Strategy for Modern Industrial Parks 2

Research on the Source-Load Interactive Scheduling Strategy ...

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2019 2nd International Symposium on Power Electronics and Control Engineering, ISPECE 2019

作者： Haibo, Tan Kai, Li Mouhai, Liu Haiyuan, Wang Cong, Tan Zhiguo, Liu Changsha410004 China Hunan Province Key Laboratory of Intelligent Electrical Measurement and Application Technology Changsha410004 China

Aiming at the problems of diversified demand for electricity, high rate of load growth, limited distribution network corridor and single power supply mode in industrial parks, this paper explores a new scheduling strategy, studies a mechanism of source-load interactive scheduling for modern industrial parks, and puts forward three scheduling strategies, namely, optimal electricity price, friendly power grid and enhanced production. The strategy has been applied in a smart industrial park of hunan Power Grid. The application results show that the method can effectively improve the power supply capacity of the modern industrial parks, reduce the total cost of electricity, and enhance the load rate of distribution transformers, and it also has high economic and practical value. © Published under licence by IOP Publishing Ltd.

关键词： Scheduling

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Mixture Design and Environmental Impact Analysis of Cement-Metakaolin-Sugarcane Bagasse Ash Ternary Composite

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SSRN 2024年

作者： Liu, Zhihua Liu, Jianhui Liu, Leping Li, Mingtao Chen, Zheng Shi, Caijun Key Laboratory of Disaster Prevention and Structural Safety of China Ministry of Education School of Civil Engineering and Architecture Guangxi University Nanning530004 China State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures Guangxi University Nanning530004 China College of Chemistry and Materials Nanning Normal University Nanning530100 China Key Laboratory for Green & Advanced Civil Engineering Materials and Application Technology of Hunan Province College of Civil Engineering Hunan University Changsha410082 China

The use of supplementary cementitious materials (SCMs) is an effective way to reduce CO2 emissions within the cement industry. In this paper, the Cement-Metakaolin (MK)-Sugarcane Bagasse ash (SCBA) ternary composite was designed based on the simplex centroid design method. The influence of MK and SCBA on mechanical properties of ternary composite was investigated. In addition, the hydration products and microstructure of ternary composite were analyzed by Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), low-field nuclear magnetic resonance (1H NMR). At the same time, the life cycle assessment (LCA) method was used to quantitatively analyze the environmental impact and economic cost of the ternary composite system. A multi-performance indicator was used to optimize the mix ratio of the ternary composite based on the simplex centroid design method, and it was concluded that the Cement: MK: SCBA ratio was 75%: 20%: 5% (by weight) to achieve the optimal synergistic effect. The findings of this study can offer a design methodology that considers both performance and environmental factors, while also providing a theoretical foundation for the utilization of SCBA in cement-based materials. © 2024, The Authors. All rights reserved.

关键词： Life cycle

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Localized Corrosion Propagation and Long-Term Corrosion Monitor of Steel Reinforcement in Cracked Concrete Exposed to Marine Environment

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SSRN 2023年

作者： Feng, Guangyan Jin, Zuquan Zhu, Deju Jiang, Yudan Wang, Xiaoxian Key Laboratory for Green & Advanced Civil Engineering Materials and Application Technology of Hunan Province College of Civil Engineering Hunan University Changsha410082 China Engineering Research Center of Concrete Technology in Marine Environment Ministry of Education Qingdao University of Technology Qingdao266033 China School of Material Science and Engineering Southeast University Nanjing211189 China

A novel custom-designed wire beam electrode (WBE) covered by mortar with different crack widths (0.1mm, 0.2mm, and 0.3mm) was applied to study the localized corrosion propagation of steel reinforcement exposed to marine environment. The evolution of corrosion current distribution maps and anodic areas were measured. Corrosion morphology of WBE and element distribution of cracked mortar were also recorded after 300 d seawater immersion. Additionally, cracked concrete specimens with steel reinforcedment were exposed to real marine environment for 1920 d and monitored by EIS methods. The results revealed that corrosion initiates from the crack, and then propagates to other electrodes through interface of steel-mortar measured by current mapping distribution of WBE technique. The corrosion propagation of steel covered by mortar with 0.1 mm crack is mainly induced by the diffusion of Cl. However, the corrosion propagation of steel covered by mortars with 0.2 and 0.3 mm cracks is determined by spread of corrosion products. The corrosion current density of steel reinforcement in cracked concrete increases exponentially with prolonged exposure time in real marine environment. The corrosion current density of steel reinforcement in concrete with a 0.1 mm longitudinal crack is 0.13 μA/cm2 after 1920 d exposure, while that of steel reinforcement in concrete with a 0.3 mm crack is 1.37 μA/cm2. © 2023, The Authors. All rights reserved.

关键词： Mortar

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