247 results on '"Luping Tang"'
Search Results
52. Application potential analysis of biochar as a carbon capture material in cementitious composites: A review
- Author
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Jun Liu, Guang Liu, Weizhuo Zhang, Zhenlin Li, Feng Xing, and Luping Tang
- Subjects
General Materials Science ,Building and Construction ,Civil and Structural Engineering - Published
- 2022
53. Valorization of municipal solid waste incineration bottom ash (MSWIBA) into cold-bonded aggregates (CBAs): Feasibility and influence of curing methods
- Author
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Jun, Liu, Zhenlin, Li, Weizhuo, Zhang, Hesong, Jin, Feng, Xing, Chaoyun, Chen, Luping, Tang, and Yanshuai, Wang
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Environmental Engineering ,Metals, Heavy ,Feasibility Studies ,Water ,Environmental Chemistry ,Incineration ,Solid Waste ,Coal Ash ,Pollution ,Waste Management and Disposal ,Carbon ,Refuse Disposal - Abstract
The municipal solid waste incineration bottom ash (MSWIBA) contains amounts of hazardous elements or composition, and its disposal to landfills may pose a serious threat to the ground water and soil. To reduce the environmental impact of MSWIBA, a novelty application into the utilization of MSWIBA for the manufacture of cold-bonded aggregates (CBAs) was investigated in this study. This study explored the impacts of curing systems on the comprehensive properties of CBAs. Furthermore, the hydrating phases of the designed CBAs were studied by X-ray diffractometer, and the micro characteristics of CBAs was analyzed by Scanning Electron Microscopy. The results show that CBAs produced from the MSWIBA had good properties with density of 1.75-1.98 g/cm
- Published
- 2022
54. Co-utilization of quarry tailings and fly ash for non-sintered ultra-lightweight aggregates (ULWAs) by autoclave technology
- Author
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Shunfeng Wang, Long Yu, Fei Yang, Weikang Zhang, Linglin Xu, Kai Wu, Luping Tang, and Zhenghong Yang
- Subjects
General Materials Science ,Building and Construction ,Civil and Structural Engineering - Published
- 2022
55. Real-time monitoring the electrical properties of pastes to map the hydration induced microstructure change in cement-based materials
- Author
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Liming Huang, Luping Tang, Ingemar Löfgren, Nilla Olsson, and Zhenghong Yang
- Subjects
General Materials Science ,Building and Construction - Published
- 2022
56. Novel recycling application of high volume municipal solid waste incineration bottom ash (MSWIBA) into sustainable concrete
- Author
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Jun Liu, Xu Fan, Zhenlin Li, Weizhuo Zhang, Hesong Jin, Feng Xing, and Luping Tang
- Subjects
Environmental Engineering ,Environmental Chemistry ,Pollution ,Waste Management and Disposal - Abstract
Since municipal solid waste incineration bottom ash (MSWIBA) contains some heavy metals that are harmful to the groundwater and soil, this study proposes an effective and new approach to deal with high-volume MSWIBA. Selecting 70% MSWIBA, 10% ordinary Portland cement (OPC), 10% fly ash/ground granulated blast furnace slag (FA/GGBFS), and 1% volume of polypropylene (PP) fiber as the raw materials, this project designed and manufactured cold-bonded fiber aggregates (CBFAs) and applied them into sustainable concrete. It was found that the water absorption of CBFAs was between 12 and 14%, the bulk density was between 900 and 1100 kg/m
- Published
- 2022
57. Investigating the influence of fly ash on the hydration behavior of cement using an electrochemical method
- Author
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Luping Tang, Jianchao Zhang, Biqin Dong, Li Gui, Shuxian Hong, Weiwen Li, Feng Xing, and Teng Xiaojuan
- Subjects
musculoskeletal diseases ,Cement ,Materials science ,fungi ,technology, industry, and agriculture ,0211 other engineering and technologies ,020101 civil engineering ,Blended cement ,02 engineering and technology ,Building and Construction ,Electrochemistry ,Positive correlation ,0201 civil engineering ,Dielectric spectroscopy ,Compressive strength ,Fly ash ,021105 building & construction ,General Materials Science ,Composite material ,Civil and Structural Engineering - Abstract
Fly ash is an industrial by-product that is widely used in the cement industry. Traditional methods used to investigate the influence of fly ash on the hydration behavior of cement are destructive and cannot accomplish a continuous tracing of the hydration process. In this study, the influence of fly ash incorporation on the hydration process of cement is evaluated using measured electrochemical data obtained from the electrochemical impedance spectroscopy approach. A novel equivalent circuit model that considers the electrochemical characteristics of cement during the hydration process is proposed to investigate the electrochemical property of the blended cement. The resistance parameter of the model, Rct1, was found to have a positive correlation with hydration degree and compressive strength during hydration. With this parameter, the method can be used to non-destructively trace and characterize the effects of fly ash incorporation on the cement hydration process.
- Published
- 2019
58. Water distribution modelling of capillary absorption in cementitious materials
- Author
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Jianchao Zhang, Biqin Dong, Luping Tang, Zhichao Liu, Chen Lin, Shuxian Hong, and Feng Xing
- Subjects
Cement ,Materials science ,medicine.diagnostic_test ,Capillary action ,Computed tomography ,Building and Construction ,Tortuosity ,Cement paste ,medicine ,General Materials Science ,Cementitious ,Composite material ,Absorption (electromagnetic radiation) ,Water content ,Civil and Structural Engineering - Abstract
In this paper, a novel capillary absorption model is proposed to investigate the capillary absorption process of cementitious materials. This model mainly consider the influence of tortuosity of the capillary pores of cement paste, which is the key factor affecting the capillary absorption process. The proposed model is verified by the capillary absorption process of paste samples with different water/cement ratios. The absorption height and water content profile of testing samples are measured by X-ray computed tomography. The results show that the proposed capillary absorption model that takes the tortuosity of capillary pores into consideration is suitable for investigating the capillary absorption process of water in cementitious materials.
- Published
- 2019
59. Temperature evolution during the compaction of calcium silicate hydrate powders using a compression calorimeter
- Author
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Zhi Jun Dong, Shuping Wang, Luping Tang, Xiaoqin Peng, Lin Lin, and Lu Zeng
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business.product_category ,Materials science ,Multiphysics ,Compaction ,Condensed Matter Physics ,Compression (physics) ,Calorimeter ,Amorphous solid ,Condensed Matter::Materials Science ,chemistry.chemical_compound ,Compressive strength ,chemistry ,Die (manufacturing) ,Physical and Theoretical Chemistry ,Composite material ,Calcium silicate hydrate ,business - Abstract
Amorphous calcium silicate hydrate (CSH) undergoes contact-hardening property, i.e. the powder can be hardened by compression. A compression calorimeter was designed to determine the temperature evolution during the compaction of the powder. A platinum sensor (Pt100) was used as the temperature sensor and was positioned in the powder as well as in the compression die. A resolution of 0.01 °C with a sampling time of every second was used to monitor the temperature. Both theoretical calculation and simulations by COMSOL multiphysics showed that the device reliably evaluated the temperature during the compaction of CSH powders. The measurement was taken under semi-adiabatic conditions. The temperature profiles obtained from the measurement revealed the compression process and bonding development during the compaction of the powders. Finally, a linear relationship was observed between the compressive strength and the maximum temperature increase. This provides insight into the contact-hardening mechanism during the compaction of CSH powders.
- Published
- 2019
60. XRD and 29Si MAS NMR study on carbonated cement paste under accelerated carbonation using different concentration of CO2
- Author
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Wei Liu, Yong-Qiang Li, Zhijun Dong, and Luping Tang
- Subjects
Cement ,Calcite ,Materials science ,Silica gel ,Carbonation ,Aragonite ,02 engineering and technology ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,chemistry.chemical_compound ,Calcium carbonate ,chemistry ,Mechanics of Materials ,Vaterite ,Materials Chemistry ,Magic angle spinning ,engineering ,General Materials Science ,0210 nano-technology ,Nuclear chemistry - Abstract
In this study, the chemical composition of cement pastes, exposed to accelerated carbonation using different concentration of CO2 (3%, 10%, 20%, 50%,100%), have been determined and compared with those of natural carbonation (0.03%). Quantitative X-ray diffraction (QXRD) and( 29)Si Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR) were used for characterisation and quantitative analysis of the carbonated phases. The obtained QXRD results revealed that the complete carbonation was hardly attained. Calcite, aragonite and vaterite were in co-existence after accelerated carbonation, while vaterite was dominant. The preferential polymorphic precipitation of the three crystal forms of calcium carbonate was affected by the carbonation degree of C-S-H and the duration of the carbonation process, but not by the concentration of CO2. The NMR results indicated that C-S-H gel was strongly decalcified, and calcium modified silica gel was formed after carbonation. The C-S-H decalcification, under all the accelerated carbonation conditions, was clearly more pronounced than that under the natural carbonation conditions. When the concentration of CO2 was in the range of 3%-20%, the ratio of decalcified to remaining C-S-H was similar, in a range of 5-6, while under the higher concentration of CO2 this ratio was increased to > 8. Therefore, in consideration of both acceleration rate and measurement uncertainty, the higher concentration, up to 20%, of CO2 in an accelerated carbonation should be applicable.
- Published
- 2019
61. Novel Interface in CuAg Nanostructure Induced by Size Effect
- Author
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Luping Tang, Lei Zhang, Tao Xu, Litao Sun, Qiubo Zhang, Wei Wu, Longbing He, and Kaihao Yu
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Nanostructure ,Materials science ,Annealing (metallurgy) ,Intermetallic ,Heterojunction ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Transmission electron microscopy ,Chemical physics ,Miniaturization ,General Materials Science ,Particle size ,Physical and Theoretical Chemistry ,0210 nano-technology ,Bimetallic strip - Abstract
Bimetallic Janus nanostructures (JNs) have been revealed to be valuable materials because they have unique intermetallic interfaces that enable their potential use in a range of applications. However, with the increasing miniaturization of electronic devices, particle sizes influence the structure and orientation of these heterointerfaces, which plays a significant role in their application. Our in situ annealing experiments with high-resolution transmission electron microscopy have shown that for particle sizes in the sub-10 nm range, CuAg JNs preferentially show a Cu(100)/Ag(100) interface, differing from the larger CuAg JNs, where the Cu(111)/Ag(111) interface is favored. We discuss a feasible atomic motion mechanism to explain the effect of particle size on the formation of different heterointerfaces. Our results reveal the presence of a novel sub-10 nm heterostructure with a unique Cu(100)/Ag(100) interface and also provide crucial insights into understanding the role of particle size in interfacial evolution during thermal annealing of heterostructures.
- Published
- 2019
62. Resourceful utilization of quarry tailings in the preparation of non-sintered high-strength lightweight aggregates
- Author
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Shunfeng Wang, Long Yu, Fei Yang, Weikang Zhang, Linglin Xu, Kai Wu, Luping Tang, and Zhenghong Yang
- Subjects
General Materials Science ,Building and Construction ,Civil and Structural Engineering - Published
- 2022
63. Electrically driven ionic transport in the RCM and RIM: Investigations based on experiments and numerical simulations
- Author
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Jun Liu, Chenyue Liao, Hesong Jin, Zhilu Jiang, Renbin Xie, and Luping Tang
- Subjects
General Materials Science ,Building and Construction ,Civil and Structural Engineering - Published
- 2022
64. Geopolymer Recycled Aggregate Concrete: From Experiments to Empirical Models
- Author
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Luping Tang, Hoai Bao Le, and Quoc-Bao Bui
- Subjects
Materials science ,0211 other engineering and technologies ,Sodium silicate ,Context (language use) ,recycled aggregate concrete (RAC) ,02 engineering and technology ,lcsh:Technology ,Article ,12. Responsible consumption ,chemistry.chemical_compound ,021105 building & construction ,11. Sustainability ,General Materials Science ,modified Feret’s model ,lcsh:Microscopy ,geopolymer ,lcsh:QC120-168.85 ,Cement ,Aggregate (composite) ,De Larrard’s model ,lcsh:QH201-278.5 ,lcsh:T ,Metallurgy ,Superplasticizer ,021001 nanoscience & nanotechnology ,Geopolymer ,Compressive strength ,fly ash ,chemistry ,lcsh:TA1-2040 ,13. Climate action ,Fly ash ,lcsh:Descriptive and experimental mechanics ,lcsh:Electrical engineering. Electronics. Nuclear engineering ,lcsh:Engineering (General). Civil engineering (General) ,0210 nano-technology ,lcsh:TK1-9971 - Abstract
Ordinary cement concrete is a popular material with numerous advantages when compared to other construction materials, however, ordinary concrete is also criticized from the public point of view due to the CO2 emission (during the cement manufacture) and the consumption of natural resources (for the aggregates). In the context of sustainable development and circular economy, the recycling of materials and the use of alternative binders which have less environmental impacts than cement are challenges for the construction sector. This paper presents a study on non-conventional concrete using recycled aggregates and alkali-activated binder. The specimens were prepared from low calcium fly ash (FA, an industrial by-product), sodium silicate solution, sodium hydroxide solution, fine aggregate from river sand, and recycled coarse aggregate. First, influences of different factors were investigated: the ratio between alkaline activated solution (AAS) and FA, and the curing temperature and the lignosulfonate superplasticizer. The interfacial transition zone of geopolymer recycled aggregate concrete (GRAC) was evaluated by microscopic analyses. Then, two empirical models, which are the modified versions of Feret’s and De Larrard’s models, respectively, for cement concretes, were investigated for the prediction of GRAC compressive strength, the parameters of these models were identified. The results showed the positive behaviour of GRAC investigated and the relevancy of the models proposed.
- Published
- 2021
- Full Text
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65. Application of LA-ICP-MS for meso-scale chloride profiling in concrete
- Author
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Silva, Nelson, Luping, Tang, and Rauch, Sebastien
- Published
- 2013
- Full Text
- View/download PDF
66. New insights into the reaction of tricalcium silicate (C3S) with solutions to the end of the induction period
- Author
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Liming Huang, Luping Tang, Haitao Gu, Zhen Li, and Zhenghong Yang
- Subjects
General Materials Science ,Building and Construction - Published
- 2022
67. The impact of cold-bonded artificial lightweight aggregates produced by municipal solid waste incineration bottom ash (MSWIBA) replace natural aggregates on the mechanical, microscopic and environmental properties, durability of sustainable concrete
- Author
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Jun Liu, Zhenlin Li, Weizhuo Zhang, Hesong Jin, Feng Xing, and Luping Tang
- Subjects
Renewable Energy, Sustainability and the Environment ,Strategy and Management ,Building and Construction ,Industrial and Manufacturing Engineering ,General Environmental Science - Published
- 2022
68. Slag Blended Cement Paste Carbonation under Different CO2 Concentrations: Controls of Mineralogy and Morphology of Products
- Author
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Shifa Lin, Yongqiang Li, Wu-Jian Long, Liu Wei, Luping Tang, and Zhijun Dong
- Subjects
Materials science ,carbonation ,Scanning electron microscope ,Carbonation ,0211 other engineering and technologies ,02 engineering and technology ,engineering.material ,lcsh:Technology ,Article ,slag ,chemistry.chemical_compound ,Vaterite ,021105 building & construction ,morphology ,Magic angle spinning ,General Materials Science ,carbonation products ,lcsh:Microscopy ,lcsh:QC120-168.85 ,Cement ,Calcite ,lcsh:QH201-278.5 ,lcsh:T ,Aragonite ,Slag ,CO2 concentration ,021001 nanoscience & nanotechnology ,chemistry ,lcsh:TA1-2040 ,visual_art ,visual_art.visual_art_medium ,engineering ,lcsh:Descriptive and experimental mechanics ,lcsh:Electrical engineering. Electronics. Nuclear engineering ,0210 nano-technology ,lcsh:Engineering (General). Civil engineering (General) ,lcsh:TK1-9971 ,Nuclear chemistry - Abstract
To investigate the effect of different CO2 concentrations on the carbonation results of slag blended cement pastes, carbonation experiments under natural (0.03% CO2) and accelerated conditions (3, 20, and 100% CO2) were investigated with various microscopic testing methods, including X-ray diffraction (XRD), 29Si magic angle spinning nuclear magnetic resonance (29Si MAS NMR) and scanning electron microscopy (SEM). The XRD results indicated that the major polymorphs of CaCO3 after carbonation were calcite and vaterite. The values of the calcite/(aragonite + vaterite) (c/(a + v)) ratios were almost the same in all carbonation conditions. Additionally, NMR results showed that the decalcification degree of C-S-H gel exposed to 0.03% CO2 was less than that exposed to accelerated carbonation, under accelerated conditions, it increased from 83.1 to 84.2% when the CO2 concentration improved from 3% to 100%. In SEM observations, the microstructures after accelerated carbonation were denser than those under natural carbonation but showed minor differences between different CO2 concentrations. In conclusion, for cement pastes blended with 20% slag, a higher CO2 concentration (above 3%) led to products different from those produced under natural carbonation. A further increase in CO2 concentration showed limited variation in generated carbonation products.
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- 2020
- Full Text
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69. Effect of the Addition of GGBS on the Frost Scaling and Chloride Migration Resistance of Concrete
- Author
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João Gomes Ferreira, Anders Lindvall, Vera Correia, and Luping Tang
- Subjects
Materials science ,Carbonation ,0211 other engineering and technologies ,GGBS ,02 engineering and technology ,lcsh:Technology ,Chloride ,chloride migration ,lcsh:Chemistry ,medicine ,General Materials Science ,salt frost resistance ,Composite material ,lcsh:QH301-705.5 ,Instrumentation ,Scaling ,Curing (chemistry) ,021102 mining & metallurgy ,Fluid Flow and Transfer Processes ,Cement ,lcsh:T ,Process Chemistry and Technology ,General Engineering ,Superplasticizer ,021001 nanoscience & nanotechnology ,lcsh:QC1-999 ,Computer Science Applications ,lcsh:Biology (General) ,lcsh:QD1-999 ,Properties of concrete ,lcsh:TA1-2040 ,Ground granulated blast-furnace slag ,concrete ,lcsh:Engineering (General). Civil engineering (General) ,0210 nano-technology ,lcsh:Physics ,medicine.drug - Abstract
Ground Granulated Blast-furnace Slag (GGBS) can partially replace cement in concrete to improve certain properties. However, some concerns regarding its performance have been raised. This research aimed at investigating the properties of concrete with GGBS, with special focus on its frost scaling and chloride ingress resistance. Concretes with different amounts of GGBS, different efficiency factors, and different air contents have been tested. The effects of other factors, namely the curing temperature, the use of superplasticizer and carbonation, have also been investigated. The results showed that the frost resistance generally decreases with the increase of the amount of GGBS. However, this research showed that it is possible to produce frost resistant concrete with up to 50% of GGBS by changing some properties of the mix (such as increasing the air content). The results also showed a significant improvement of the chloride ingress resistance for concrete with high additions of GGBS.
- Published
- 2020
- Full Text
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70. Rapid positioning of nasogastric tube by ultrasound in COVID-19 patients
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Xiao Chen, Xiao Lu, Luping Tang, Anyu Qian, Mao Zhang, and Shanxiang Xu
- Subjects
medicine.medical_specialty ,2019-20 coronavirus outbreak ,Coronavirus disease 2019 (COVID-19) ,business.industry ,ultrasound ,Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) ,Ultrasound ,Pneumonia, Viral ,lcsh:Medical emergencies. Critical care. Intensive care. First aid ,COVID-19 ,lcsh:RC86-88.9 ,Critical Care and Intensive Care Medicine ,Emergency medicine ,Research Letter ,Medicine ,Humans ,Tube (fluid conveyance) ,business ,nasogastric tube ,Coronavirus Infections ,Intubation, Gastrointestinal ,Pandemics ,Ultrasonography, Interventional - Published
- 2020
71. Utilisation of municipal solid waste incinerator (MSWI) fly ash with metakaolin for preparation of alkali-activated cementitious material
- Author
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Luping Tang, Jun Ren, Jun Liu, and Lu Hu
- Subjects
021110 strategic, defence & security studies ,Ettringite ,Environmental Engineering ,Materials science ,Health, Toxicology and Mutagenesis ,Metallurgy ,0211 other engineering and technologies ,Sodium silicate ,02 engineering and technology ,Pozzolan ,010501 environmental sciences ,01 natural sciences ,Pollution ,chemistry.chemical_compound ,Compressive strength ,chemistry ,Fly ash ,Environmental Chemistry ,Cementitious ,Leaching (metallurgy) ,Waste Management and Disposal ,Metakaolin ,0105 earth and related environmental sciences - Abstract
The proper treatment on hazardous municipal solid waste incineration fly ash (MSWIFA) is important. The application of alkali-activation technology to prepare alkali-activated MSWIFA (AAFA) material provides a potential not only to immobilise the heavy metals, but also to trigger its pozzolanic property in manufacturing building material. In this study, in addition to investigate the feasibility of alkaline activation technology in preparing AAFA with sodium silicate activator, the effect of metakaolin in AAFA (AAFM) was also explored to enhance its performance. The results showed that, compared to the AAFA, blending 10 % metakaolin in AAFA significantly improved both 28-day and 90-days compressive strengths, which was almost 200 % higher than that of AAFA. The compressive strength was increased with increasing the dosage of sodium silicate. The C-S-H gel was observed as the main hydration product of AAFA and AAFM. Moreover, the ettringite was observed in AAFM due to the reaction between the CaSO4 in MSWIFA and aluminate phase from metakaolin. Finally, the 28 and 210-day leaching behaviours of AAFM on Zn, Cu, Pb, Cd, Cr and Ni were successfully suppressed to less than 1 % of that originally from MSWIFA, which can meet the requirement from Chinese standards.
- Published
- 2020
72. Nanoengineering Microstructure of Hybrid C-S-H/Silicene Gel
- Author
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Jinyang Jiang, Qi Zheng, Xinle Li, Shaofan Li, Luping Tang, Chen Chen, and Jin Yu
- Subjects
chemistry.chemical_compound ,Molecular dynamics ,Materials science ,chemistry ,Chemical engineering ,Silicene ,General Materials Science ,Nanoengineering ,Calcium silicate hydrate ,Microstructure ,Nanomaterials - Abstract
Two-dimensional (2D) materials have been incorporated into calcium silicate hydrate (C-S-H) gel to enhance its mechanical performance for decades, while the modified C-S-H gel exhibits poor toughness, tensile strength, and ductility. In this work, we report a new design strategy and synthesis route to strengthen C-S-H interface by intercalating a silicene sheet of one atom thickness. The hybrid C-S-H/Silicene gel shows superb mechanical properties, with a remarkable enhancement in strength and other functional properties. By using density functional theory (DFT) and molecular dynamics (MD) simulations, we have demonstrated that Si-O bonds between silicene and C-S-H are stable and covalent, and the interaction energy of this bilayer gel nearly doubles by forming a 3D covalent network with a strong bridging effect. Owing to its better crystallinity enrichment and its induced dislocation dissipation mechanism, the hybrid C-S-H/Silicene gel possesses a higher tensile ductility (∼118% average enhancement and ∼228% in the
- Published
- 2020
73. Probing the beam-induced heating effect inside a transmission electron microscope by nanoparticle labels
- Author
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Hua Hong, Luping Tang, Litao Sun, Lei Zhang, Yu-Feng Yang, and Longbing He
- Subjects
Materials science ,business.industry ,Chemical technology ,Biomedical Engineering ,Nanoparticle ,Bioengineering ,TP1-1185 ,Condensed Matter Physics ,Transmission electron microscopy ,TA401-492 ,Optoelectronics ,General Materials Science ,business ,Materials of engineering and construction. Mechanics of materials ,Heating effect ,Beam (structure) - Abstract
Beam-induced heating effect on nanoscale samples is a crucial question as it strongly influences the interpretation of observed unusual behaviors. This question is currently under debate without a convincing conclusion. Here, using silver nitride (Ag 3 N) nanoparticles as temperature labels, we perform an investigation on this heating effect inside a transmission electron microscope (TEM) under normal imaging conditions. Combined with experimental measurements and semi-quantitative calculations, a temperature increase of more than 100 K is estimated and confirmed in the graphite carbon nitride (g-C 3 N 4 ) films. Strong temperature gradients are found to exist in the single-end fixed g-C 3 N 4 films. The influencing factors of heat accumulation are also investigated and discussed. Findings in this paper may shed some light on the understanding of the abnormal behaviors of nano-objects observed inside TEM.
- Published
- 2020
74. Assessment of compositional changes of carbonated cement pastes subjected to high temperatures using in-situ Raman mapping and XPS
- Author
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Zhijun Dong, Liu Wei, Biqin Dong, Luping Tang, Feng Xing, Xiaobo Ding, Yongqiang Li, and Tangwei Mi
- Subjects
Calcite ,Cement ,Materials science ,Carbonation ,Building and Construction ,Silicate ,law.invention ,chemistry.chemical_compound ,symbols.namesake ,chemistry ,X-ray photoelectron spectroscopy ,Chemical engineering ,Mechanics of Materials ,law ,Vaterite ,Architecture ,symbols ,Crystallization ,Safety, Risk, Reliability and Quality ,Raman spectroscopy ,Civil and Structural Engineering - Abstract
This paper presents a new method for assessing the compositional changes of carbonated cement pastes subjected to high temperatures. In this new method, in-situ Raman mapping combined with X-ray photoelectron spectroscopy (XPS) was used to monitor the phase transformation in carbonated cement pastes subjected to various high temperatures from 30 to 950 degrees C. Two kinds of carbonated areas, i.e., vaterite dominated and calcite dominated, were found in the in-situ Raman measurements. With the elevation in temperature, most of the vaterite was converted to calcite at 500 degrees C and completely decomposed at 600 degrees C, while the decomposition of calcite started at 600 degrees C and finished at 720 degrees C. Meanwhile, the depolymerization of the calcium modified silica gel to the silicate phases with a lower degree of polymerization was initiated at 500 degrees C, which led to the crystallization of beta-C2S at 600 degrees C. The generation of beta-C2S was found to increase with the elevation in temperature and became the dominant phase at 950 degrees C. In conclusion, the high temperature could affect the stability of carbonated cement pastes at 500 degrees C and above. The in-situ Raman mapping measurement has provided an extraordinary view of the spatial distribution of interesting phases subjected to high temperatures in a nondestructive way, which should be more consistent with the true condition in the material.
- Published
- 2022
75. Predicting degradation of the anode–concrete interface for impressed current cathodic protection in concrete
- Author
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Zareen Abbas, Luping Tang, and Emma Qingnan Zhang
- Subjects
Materials science ,020209 energy ,Interface (computing) ,Nuclear engineering ,0211 other engineering and technologies ,02 engineering and technology ,Building and Construction ,Corrosion ,Anode ,Cathodic protection ,021105 building & construction ,0202 electrical engineering, electronic engineering, information engineering ,Linear relation ,Degradation (geology) ,General Materials Science ,Current (fluid) ,Current density ,Civil and Structural Engineering - Abstract
Impressed current cathodic protection and prevention techniques are efficient methods to stop or prevent corrosion in steel reinforced concrete structures. The inevitable side effect of the current exchange is acidification at the anode–concrete interface. Accelerated test methods can be used to investigate the long-term performance of the system. However, a linear relation will not hold between the accelerated and normal conditions because of the influence of the current density. This paper presents results of an accelerated test. A power-relation conversion model is proposed and an acceleration factor is introduced.
- Published
- 2018
76. Influence of Hydrothermal Synthesis Conditions on the Formation of Calcium Silicate Hydrates: from Amorphous to Crystalline Phases
- Author
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Cong Lan, Shuping Wang, Luping Tang, Xiaoqin Peng, and Lu Zeng
- Subjects
Materials science ,Xonotlite ,Tobermorite ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Hydrothermal circulation ,0104 chemical sciences ,Amorphous solid ,Crystallinity ,chemistry.chemical_compound ,Chemical engineering ,chemistry ,Calcium silicate ,Hydrothermal synthesis ,General Materials Science ,sense organs ,Calcium silicate hydrate ,0210 nano-technology - Abstract
Hydrothermal treatment has been widely applied in the synthesis of well crystalline calcium silicate hydrate (CSH), such as tobermorite and xonotlite. However, both morphology and crystallinity of CSH are greatly affected by the conditions of hydrothermal treatment including siliceous materials, temperature increase rate and isothermal periods. In this study, the influence of hydrothermal conditions on the growth of nano-crystalline CSH was investigated based on XRD analysis. Results showed that siliceous materials with amorphous nature (i e, nano silica powder) are beneficial to synthesize pure amorphous CSH, while the use of more crystallized siliceous materials (i e, diatomite and quartz powder) leads to producing crystalline CSH. Results also indicate that the formation of tobermorite and xonotlite is greatly affected by the temperature rise rate during hydrothermal treatment.
- Published
- 2018
77. On the Mechanical Recycling of Decommisioned Insulation Polymer Composite Components
- Author
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Grammatikos, Sotirios A., Tsampas, Spyros Anastasios, Papatzani, Styliani, Luping, Tang, Löfgren, Ingemar, Petterson, Jocke, Grammatikos, Sotirios A., Tsampas, Spyros Anastasios, Papatzani, Styliani, Luping, Tang, Löfgren, Ingemar, and Petterson, Jocke
- Abstract
Fibre reinforced polymer composites (FRPs) are being increasingly used in aerospace and automotive applications due to their high specific mechanical properties. The construction industry has also started taking advantage of the potential of FRPs for both structural and non-structural purposes. The result of this remarkable absorption of FRPs within the worldwide production market, has led to an immense increase of decommissioned thermoset-matrix components. Nowadays, the majority of the decommissioned FRP components are recovered energy-wise through incineration or simply discarded in landfills around the globe. Within the framework of this paper, we present a solution for the extension of the service life of decommissioned FRP components. Decommissioned electrical insulation FRP pipes were granulated and incorporated as fillers within both cementitious and polymer matrix composites. The effect of FRP granulates on the mechanical performance of cementitious and polymer matrix composites is examined to determine the maximum granulate-filler fraction that can be recycled without compromising the mechanical performance and manufacturing process. © 2020 IOP Publishing Ltd. All rights reserved., Funding details: 2017-001986; Funding text 1: This work was funded by RECYTAL project (Vinnova/Energimyndigheten/Formas (Sweden) - RESource utlysning 2 (2016-2017), Project reference: 2017-001986). Authors are thankful to Marek Machowski (Chalmers University of Technology) and Peter Hellström (Swerea Sicomp) for their contribution to experimental testing. ABB Composites, Sweden, is greatly acknowledged for supplying discarded insulation FRP tubes whereas RAPID Granulator, Sweden, for shredding FRP tubes into fragments.
- Published
- 2020
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78. Tensile behaviour of carbon fabric reinforced cementitious matrix composites as both strengthening and anode materials
- Author
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Jun Liu, Ji-Hua Zhu, Meini Su, Feng Xing, Liu Wei, Liangliang Wei, Tamon Ueda, and Luping Tang
- Subjects
Materials science ,Composite number ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Reinforced concrete ,Anode ,Cathodic protection ,020303 mechanical engineering & transports ,0203 mechanical engineering ,Ultimate tensile strength ,Ceramics and Composites ,Composite material ,0210 nano-technology ,Polarization (electrochemistry) ,Cementitious matrix ,Reinforcement ,Civil and Structural Engineering - Abstract
Recently, a promising solution to corroded steel reinforced concrete structures was proposed in which a dual-functional carbon-fabric reinforced cementitious matrix (carbon-FRCM) composite is used for impressed current cathodic protection (ICCP) and structural strengthening (SS); this method is referred to as ICCP-SS. The tensile behaviour of carbon-FRCM must be understood for design purposes. In this study, the tensile characteristics of carbon-FRCM composites with different fabric reinforcement ratios were assessed to determine the strengthening capability of the materials. Then, using the composite as an anode material, the tensile behaviour of carbon-FRCM specimens subjected to anodic polarization in ICCP was evaluated. Direct tensile tests were conducted to obtain the tensile stress-strain behaviour of the carbon-FRCM specimens. By comparing the results from each case, the influences of different parameters on the tensile behaviour of the carbon-FRCM composites were evaluated, and useful information regarding the application of these materials in ICCP-SS was obtained.
- Published
- 2019
79. Self-catalytic VLS growth one dimensional layered GaSe nanobelts for high performance photodetectors
- Author
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Hong Zhou, Tiefeng Yang, Shuangping Yuan, Bing-Xin Zhou, Luping Tang, and Zixiang Zhao
- Subjects
Photoluminescence ,Materials science ,business.industry ,Transistor ,Wide-bandgap semiconductor ,Photodetector ,02 engineering and technology ,General Chemistry ,Chemical vapor deposition ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,law.invention ,Responsivity ,Semiconductor ,law ,Optoelectronics ,General Materials Science ,Vapor–liquid–solid method ,0210 nano-technology ,business - Abstract
Layered GaSe is an important binary semiconductor because of its anisotropic crystallography characteristics, wide band gap and attractive optical and electrical properties. Here, we report the self-catalytic growth of GaSe nanobelts via a simple chemical vapor deposition method. The quality of the as-grown nanobelts have been confirmed by transmission electron microscope and photoluminescence spectra. The field-effect transistors based on these individual GaSe nanobelts have been fabricated and show p-type semiconducting behaviors and on-off ratio of 106. The GaSe nanobelts not only show good responsivity of 164.4 A W−1, but also exhibit excellent stability and reliability, which are superior to their bulk counterparts. These results make GaSe nanobelt a promising optoelectronic material in integrated electronic/optoelectronic devices.
- Published
- 2018
80. Effect of the paste-anode interface under impressed current cathodic protection in concrete structures
- Author
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Helén Jansson, Luping Tang, Diana Bernin, and Emma Qingnan Zhang
- Subjects
accelerated test ,Materials science ,020209 energy ,microstructure ,0211 other engineering and technologies ,02 engineering and technology ,cathodic protection ,Infrastructure Engineering ,CFRP anode ,Cathodic protection ,Corrosion ,021105 building & construction ,0202 electrical engineering, electronic engineering, information engineering ,Materials Chemistry ,Environmental Chemistry ,Composite material ,calcium dissolution ,Dissolution ,Composite Science and Engineering ,Carbon fiber reinforced polymer ,Mechanical Engineering ,Metals and Alloys ,Corrosion Engineering ,General Medicine ,Condensed Matter Physics ,Microstructure ,paste–anode interface ,Surfaces, Coatings and Films ,Anode ,Mechanics of Materials ,Current (fluid) ,Other Chemistry Topics ,Current density - Abstract
Impressed current cathodic protection (ICCP) is a powerful method to prevent and stop corrosion of steel in concrete structures. To evaluate the long-term effect of ICCP, accelerated tests have been adopted using high current densities. A carbon fiber reinforced polymer mesh was introduced as anode. The presented research focused on the changes at the paste-anode interface as a consequence of applying current. The treated samples were characterized by various techniques. Calcium dissolution was found with an average thickness of 0.34 mm around the anode after charges of 6*10^6 C/m2 were applied, equivalent to applying 4 mA/m2 of anode surface for 30 years. Calcium dissolution resulted in a white zone around the anode, where the calcium silica ratio was lowered and almost no crystal phase was observed. NMR results show clear Q3 and Q4 peaks in the white zone, which contained extended branched and networked structures of hardened cement paste. An increased resistance caused by the formation of the white zone may eventually make the system fail because of insufficient current densities. CFRP has been proven suitable for ICCP application even at a current density of 4 A/m2 of anode surface.
- Published
- 2018
81. Novel behaviors/properties of nanometals induced by surface effects
- Author
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Lei Zhang, Luping Tang, Litao Sun, Qiubo Zhang, Jun Sun, and Longbing He
- Subjects
Surface (mathematics) ,Materials science ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,0104 chemical sciences ,Electronic, Optical and Magnetic Materials ,Characterization (materials science) ,Biomaterials ,Long period ,Materials Chemistry ,0210 nano-technology - Abstract
Surface effect is believed as one of the most important origins from which the novel properties of nanomaterials derive. Although this effect has been investigated for decades, the understanding of the essential correlations between materials' structures and their unique properties still has a long way to go. Recently, the innovation of aberration-correction techniques in electron microscopy, as well as the fast-developing in situ techniques, has made a big step toward unveiling the mysterious mechanisms underlying the unusual behaviors. In this review, we summarize the surface effect-induced extraordinary phenomena of nanometals that were uncovered recently, including peculiar mechanical behaviors, unusual thermal instabilities, remarkable electromigrations, unconventional structure evolution, and phase separations. All these findings apparently give an in-depth understanding of the novelties that appeared only in nanometals, such as the rubber-like or liquid-like deformation behaviors in mechanics, the size-dependent melting and wetting behaviors in thermodynamics and surface science, the atomic-scale welding and mass conveying in electrics, and the size- or composition-dependent phase segregations in kinetics and metallography. Such abundant knowledge not only extends the classical theories established on bulk materials but also can provide valuable instructions for future applications of nanometals such as the design of versatile functional nanodevices like sensors and actuators. By using the state-of-the-art characterization techniques, tremendous progress has been made toward approaching the truth on what factors essentially govern the discrepancies between nanometals and their bulk counterparts. Moreover, this review also opens up a discussion on several surface effect-related controversies that have been retained for a long period. Finally, a brief perspective is presented on the basis of upcoming new techniques in electron microscopy, giving an imagination of viewing and measuring the surface structures and properties directly.
- Published
- 2018
82. Numerical model of the effect of water vapor environment on the chloride transport in concrete
- Author
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Luping Tang, Chenyue Liao, Hesong Jin, Jun Liu, Zhi Lu Jiang, and Daojun Zhong
- Subjects
Materials science ,Capillary action ,Diffusion ,Multiphysics ,Humidity ,Context (language use) ,Building and Construction ,Chloride ,Ion ,medicine ,General Materials Science ,Composite material ,Water vapor ,Civil and Structural Engineering ,medicine.drug - Abstract
Chloride ions are known as one of the most crucial factors for rebar corrosion in reinforced concrete (RC) structures exposed to marine environments under drying-wetting cycles. In this condition, the chloride ion content in unsaturated concrete will change under the coupled effect of diffusion and capillary suction. This study simulates the atmosphere zone of the marine environment to explore the law of the chloride transmission behavior under the context of constant temperature and humidity. To analyze the effect of different drying-wetting ratios on the chloride ion profile in the concrete by conducting the dry-wet cycle tests. It is found that the most unfavorable drying-wetting ratios for RC structures in this study is 1:5.5. A finite element numerical model of chloride ion transmission based on Fick's Ⅱ law was established by COMSOL Multiphysics. It can be used to predict the range of concrete surface chloride ion concentration, and dynamic change of the distribution of chloride ion concentration inside the RC structures under different drying-wetting cycles over time. The comparison of experiment data and simulation results verify that the chloride diffusion prediction model has a good correlation.
- Published
- 2021
83. In situ observation of the solid solution-induced sublimation of CuAg Janus nanoparticles
- Author
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Litao Sun, Longbing He, Hui Dong, Lei Shi, Luping Tang, Tao Xu, Lei Zhang, and Wei Wu
- Subjects
Materials science ,Annealing (metallurgy) ,Mechanical Engineering ,Metals and Alloys ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Catalysis ,Chemical engineering ,Mechanics of Materials ,Transmission electron microscopy ,Phase (matter) ,Materials Chemistry ,Thermal stability ,Sublimation (phase transition) ,0210 nano-technology ,Bimetallic strip ,Solid solution - Abstract
Bimetallic Janus nanostructures (JNs) have attracted much interest because of their promising potential applications induced by unique interface effects, especially in catalysis. Catalytic stability acts a role as significant as catalytic efficiency in the potential applications of catalysts. However, the response of bimetallic JNs to high temperature has been poorly investigated due to their complex structure and sublimation kinetics. Herein, the thermal stability and sublimation mechanisms of CuAg JNs are studied through in situ annealing experiments performed in an aberration-corrected FEI Titan 80-300 transmission electron microscope operated at 300 kV. It is proven that CuAg JNs begin to sublimate until the temperature increases to 800 °C, although Ag nanostructures can always begin to sublimate at temperatures as low as 500 °C. Interestingly, Cu and Ag atoms sublimate simultaneously with a molar ratio likely to preserve at approximately 1 because Cu partially dissolves into the Ag phase at higher temperatures. Furthermore, a rational atomic motion mechanism is proposed to explain the phase transition in which the solid solution forms and the whole special sublimation process. These in situ observations promise to be helpful for understanding the evolutionary behaviors of bimetallic JNs under high temperatures arising in catalytic processes and other applications.
- Published
- 2021
84. Chloride penetration in freeze–thaw induced cracking concrete: A numerical study
- Author
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Zhe Hu, Peng Zhang, Lin jie Li, Luping Tang, Qing-feng Liu, and Yong Wen
- Subjects
FTCS scheme ,Work (thermodynamics) ,Materials science ,Fracture mechanics ,Building and Construction ,Chloride ,Durability ,Cracking ,medicine ,General Materials Science ,Geotechnical engineering ,Diffusion (business) ,Porosity ,Civil and Structural Engineering ,medicine.drug - Abstract
Reinforced concrete (RC) structures, serving in marine and cold environments, are attacked by freeze–thaw cycles (FTCs) and chloride penetration, both of which can cause serious deterioration of RC structures. Existing studies lack of models considering the development of pore structure, as well as crack propagation caused by freeze and thaw. In this study, a multi-phase numerical model is proposed for studying chloride transport in concrete under FTCs. Unlike the existing models, the diffusion coefficient in the presented work is associated with the evolution of pore structure, and the induced crack is considered to be time-dependent and propagates with cycles of freeze–thaw action. The validity of the presented model is verified against a set of third-party experiments. Some important factors, such as FTCs, crack width, porosity, connectivity and most probable pore diameter factor are elaborated to illustrate how these factors affect chloride transport. The findings can bring insights to the durability design of RC structures serving in cold or marine regions.
- Published
- 2021
85. Influence of deicing salt on the surface properties of concrete specimens after 20 years
- Author
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Luping Tang, Weizhuo Zhang, Zhenlin Li, Jun Liu, and Hesong Jin
- Subjects
chemistry.chemical_classification ,Materials science ,Silica fume ,Metallurgy ,Iodide ,0211 other engineering and technologies ,Slag ,020101 civil engineering ,02 engineering and technology ,Building and Construction ,Chloride ,Durability ,0201 civil engineering ,Corrosion ,chemistry ,Properties of concrete ,Ground granulated blast-furnace slag ,visual_art ,021105 building & construction ,medicine ,visual_art.visual_art_medium ,General Materials Science ,Civil and Structural Engineering ,medicine.drug - Abstract
The low temperature of ice and snow all year round in Sweden leads to the common use of deicing salt to melt the roads, but the splash of the deicing salt on the reinforced concrete (RC) on both sides of the roads brings about the deterioration of the durability of RC components. The chloride ions diffusion coefficient is an important parameter to evaluate the durability of RC. By adopting the rapid chloride migration method (RCM) and replacing chloride ions with iodide ions, the samples of concrete blocks exposed on the side of the highway for 20 years were taken. This is directly beneficial to study the influence of the type, content, and water-cement ratio of mineral additions on the diffusion and distribution of iodide ions in concrete and analyze the surface environmental effect depth of concrete. The influence of chloride ions on the pore structure and microscopic morphology of concrete also were studied by scanning electron microscope-energy dispersive spectrum and X-ray diffractometer. The results show that as the water-cement ratio increases, the surface environmental effect depth of concrete and the diffusion area of iodide ions gradually increase. Silica fume and ground granulated blast furnace slag (GGBF slag) have an impediment to the diffusion of iodide ions, especially with the high volume of the GGBF slag (about 50%), the diffusion of iodide ions is very low. In general, this research is helpful to provide some empirical ideas and suggestions for the manufacturing and durability design of concrete structures in marine environments or deicing salt road environments.
- Published
- 2021
86. On the Mechanical Recycling of Decommisioned Insulation Polymer Composite Components
- Author
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Grammatikos, Sotirios, primary, Tsampas, Spyros, additional, Papatzani, Styliani, additional, Luping, Tang, additional, Löfgren, Ingemar, additional, and Petterson, Jocke, additional
- Published
- 2020
- Full Text
- View/download PDF
87. Chemical and mineralogical characteristics of carbonated and uncarbonated cement pastes subjected to high temperatures
- Author
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Yongqiang Li, Tangwei Mi, Biqin Dong, Luping Tang, Zhijun Dong, Feng Xing, and Liu Wei
- Subjects
Cement ,Calcite ,Materials science ,Mechanical Engineering ,Carbonation ,02 engineering and technology ,engineering.material ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Industrial and Manufacturing Engineering ,Amorphous calcium carbonate ,Portlandite ,Silicate ,0104 chemical sciences ,chemistry.chemical_compound ,Calcium carbonate ,chemistry ,Mechanics of Materials ,Vaterite ,Ceramics and Composites ,engineering ,Composite material ,0210 nano-technology - Abstract
The fire-resistance of carbonated concrete under high temperatures is significant due to its direct exposure during an accidental fire. To evaluate the carbonation effect on fire-resistance of concrete, the chemical and mineralogical changes of uncarbonated and carbonated cement pastes subjected to high temperatures were thoroughly investigated in this research by employing micro-measurement methods including thermal-gravimetric analysis (TGA), X-ray diffraction (XRD) and 29Si nuclear magnetic resonance (29Si NMR). Uncarbonated cement paste results showed the decomposition of portlandite at 400 °C with the formation of lime, whilst the depolymerization of C–S–H happened simultaneously to generate monomeric silicon tetrahedron. Above 720 °C, all the C–S–H depolymerized to crystalline C2S. Carbonated cement pastes on the other hand showed that amorphous calcium carbonate and part of vaterite decomposed between the range of 400–600 °C, while the rest of the vaterite and calcite were decomposed at 600–720 °C. The individual content of calcium carbonate polymorph could not be obtained using a TGA curve. Besides, the calcium-modified silicate gel was significantly decomposed at 500 °C and completely depolymerized to crystalline C2S at 950 °C. In summary, carbonated pastes show better resistance to high temperatures with its heat absorption capacity 3.3 times as high as the uncarbonated sample, which delays the temperature development in the inner layer. Therefore, a reasonable carbonation process could help to improve the fire resistance of concrete to some extent.
- Published
- 2021
88. Effect of silica fume on the mechanical property and hydration characteristic of alkali-activated municipal solid waste incinerator (MSWI) fly ash
- Author
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Jun Liu, Feng Xing, Lu Hu, Luping Tang, Zhijun Dong, and Jun Ren
- Subjects
Municipal solid waste ,Materials science ,Silica fume ,020209 energy ,Strategy and Management ,Modulus ,Sodium silicate ,02 engineering and technology ,complex mixtures ,Industrial and Manufacturing Engineering ,chemistry.chemical_compound ,0202 electrical engineering, electronic engineering, information engineering ,0505 law ,General Environmental Science ,Renewable Energy, Sustainability and the Environment ,fungi ,05 social sciences ,Metallurgy ,technology, industry, and agriculture ,Building and Construction ,respiratory system ,Microstructure ,Incineration ,Compressive strength ,chemistry ,Fly ash ,050501 criminology - Abstract
The incorporation of silica fume provides the solution to solve the low silica content of municipal solid waste incinerator fly ash, which hinders its utilisation in manufacturing alkali-activated solid waste incinerator fly ash. This paper reported the effect of silica fume and sodium silicate nature on the hardened properties, including compressive strength, hydration product and microstructure of alkali-activated municipal solid waste incinerator fly ash. In addition to characterising the property of municipal fly ash, the effect of silica fume in compressive strength of alkali-activated municipal solid waste incinerator fly ash under different sodium silicate dosage and modulus was investigated and its hydration products were determined by XRD and SEM. The results demonstrated that adding silica fume significantly improved the compressive strength by promoting the formation of C–S–H hydration product. Moreover, a higher sodium silicate content and modulus resulted in a higher compressive strength. The concentration of leachable heavy metals from harden specimen with 10% SF specimen was significantly reduced to the value which is much lower than the recommendation from Chinese standards.
- Published
- 2021
89. Corrosion induced stress field and cracking time of reinforced concrete with initial defects: Analytical modeling and experimental investigation
- Author
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Shazim Ali Memon, Feng Xing, Hongfang Sun, Luping Tang, Minhui Li, Xiaogang Zhang, and Guojun Ma
- Subjects
Materials science ,Field (physics) ,General Chemical Engineering ,0211 other engineering and technologies ,02 engineering and technology ,General Chemistry ,Stress distribution ,021001 nanoscience & nanotechnology ,Reinforced concrete ,Corrosion ,Stress field ,Cracking ,Induced stress ,021105 building & construction ,General Materials Science ,Composite material ,0210 nano-technology ,Concrete cover - Abstract
This paper presents an analytical model for calculation of corrosion induced stress field and cracking time of concrete cover with initial defects in a reinforced concrete. In the proposed model, two types of initial defects in concrete cover (surface and middle defect) were considered. Experiments were also performed to validate the effectiveness and accuracy of the proposed model. Based on the model analysis, it was found out that initial defects have significant influence on the stress distribution, the corrosion induced expansion pressure in concrete cover, the critical mass of corrosion products, and the cracking time of concrete cover.
- Published
- 2017
90. Influence of drying conditions on the contact-hardening behaviours of calcium silicate hydrate powder
- Author
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Xiaoqin Peng, Shuping Wang, Luping Tang, Zhilong Tao, and Lu Zeng
- Subjects
Materials science ,Binding properties ,Metallurgy ,0211 other engineering and technologies ,02 engineering and technology ,Building and Construction ,021001 nanoscience & nanotechnology ,Microstructure ,Bulk density ,Amorphous solid ,chemistry.chemical_compound ,chemistry ,021105 building & construction ,Mechanical strength ,Hardening (metallurgy) ,General Materials Science ,Composite material ,Calcium silicate hydrate ,0210 nano-technology ,Water content ,Civil and Structural Engineering - Abstract
Contact-hardening is a new type of binding property for amorphous calcium silicate hydrate (C-S-H) with which a hardened specimen can be prepared in a few minutes by compressing C-S-H powders directly. However, the relation between contact-hardening behaviours and the drying conditions of powders is still poorly understood. In this study, the influence of air-drying and oven-drying on the physical properties and microstructure of hydrothermally synthesised C-S-H powders were investigated. The results provide further insight into the contact-hardening behaviours of these powders by measuring the bulk density, mechanical strength and water-resistant properties of the compacts. Factors affecting particleparticle contact and hardening of C-S-H powders are discussed in parallel with the mechanical properties and microstructure of the compacts. The result highlights that the moisture content, which is highly related to the drying conditions, is essential to contact hardening of C-S-H.
- Published
- 2017
91. Possible pitfall in sample preparation for SEM analysis - A discussion of the paper 'Fabrication of polycarboxylate/graphene oxide nanosheet composites by copolymerization for reinforcing and toughening cement composites' by Lv et al
- Author
-
Hongzhi Cui, Feng Xing, Xiantong Yan, and Luping Tang
- Subjects
Cement ,Ettringite ,Materials science ,Calcium hydroxide ,Graphene ,Carbonation ,Oxide ,02 engineering and technology ,Building and Construction ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,chemistry ,law ,General Materials Science ,Cementitious ,Composite material ,0210 nano-technology ,Nanosheet - Abstract
This paper presents a discussion of the paper published by Lv et al. in Cement and Concrete Composites, 2016, 66: 1–9. The discussion is mainly focused on whether or not graphene oxide (GO) nanosheets can regulate formation of flower-like cement hydration crystals. Lv et al. in their paper proposed a regulation mechanism stating that GO nanosheets can control ettringite (AFt), monosulfate (AFm) and calcium hydroxide (CH) to form the flower-like and polyhedron crystals, whilst our experimental results show that there might be a possible pitfall in sample preparation for SEM analysis. It is here suggested that the main chemical components of flower-like and polyhedron crystals are calcium carbonates, which are not the products from cement hydration but from carbonation of cementitious hydrates. It is therefore suggested that further study is needed to verify the regulation mechanism of GO on cement hydration crystals proposed by Lv et al. in the discussed paper.
- Published
- 2017
92. Improved Interfacial Bonding Strength and Reliability of Functionalized Graphene Oxide for Cement Reinforcement Applications
- Author
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Shuping Wang, Luping Tang, Abdelhafid Zehri, Behabitu Ergette Tebikachew, Björn Cullbrand, Lilei Ye, Johan Liu, and Nan Wang
- Subjects
Cement ,Fabrication ,010405 organic chemistry ,Chemistry ,Graphene ,Organic Chemistry ,Oxide ,General Chemistry ,010402 general chemistry ,01 natural sciences ,Catalysis ,0104 chemical sciences ,Nanomaterials ,law.invention ,chemistry.chemical_compound ,Covalent bond ,law ,Ultimate tensile strength ,Surface modification ,Composite material - Abstract
Poor bonding strength between nanomaterials and cement composites inevitably lead to the failure of reinforcement. Herein, a novel functionalization method for the fabrication of functionalized graphene oxide (FGO), which is capable of forming highly reliable covalent bonds with cement hydration products, and therefore, suitable for use as an efficient reinforcing agent for cement composites, is discussed. The bonding strength between cement and aggregates was improved more than 21 times with the reinforcement of FGO. The fabricated FGO also demonstrated many important features, including high reliability in cement pastes, good dispersibility, and efficient structural refinement of cement hydration products. With the incorporation of FGO, cement mortar samples demonstrated up to 40 % increased early and ultimate strength. Such results make the fast demolding and manufacture of light constructions become highly possible, and show strong advantages on improving productivity, saving cost, and reducing CO2 emissions in practical applications.
- Published
- 2019
93. The Surface Moisture Transport Model for Cement Mortar under Dry-Wet Cycles
- Author
-
Luping Tang, Jouni Punkki, Jianming Gao, Yanjuan Chen, and Materials and Chemistry
- Subjects
Cement ,Materials science ,Moisture ,Surface moisture ,Water flow ,Composite material ,Durability ,Cement mortar - Abstract
The moisture transport character is an important transport properties of cement-based materials, especially under the periodically dry-wet circumstance, that mostly influence the durability of these materials. In this paper, a novel model describing the quantity of moisture in and out the exposed surface of cement mortar under dry-wet cycles is presented. This model could be easily applied to estimate the quantity of water flow in and out the exposed surface of cement-based materials under dry-wet cycles, with necessary input parameters which could be obtained by simple test methods. The calculation program involved in this model could be realized readily. © 2019, The Authors. All rights reserved.
- Published
- 2019
94. Synthesis and Properties of Red Mud-Based Nanoferrite Clinker
- Author
-
Feng Xing, Li Ling, Luping Tang, Shazim Ali Memon, Zhu Ding, Chuyu Chen, Weiwen Li, and Hongfang Sun
- Subjects
Cement ,Materials science ,Article Subject ,Metallurgy ,0211 other engineering and technologies ,Environmental pollution ,02 engineering and technology ,Raw material ,021001 nanoscience & nanotechnology ,Clinker (cement) ,Industrial waste ,Red mud ,law.invention ,Portland cement ,law ,lcsh:Technology (General) ,021105 building & construction ,lcsh:T1-995 ,General Materials Science ,Cementitious ,0210 nano-technology - Abstract
Red mud, an industrial waste obtained from alumina plants, is usually discharged into marine or disposed into a landfill polluting the surrounding water, atmosphere, and soil. Thus, disposal of red mud is an environmental concern and it should be recycled in an effective way. Since red mud consists of iron- and aluminum-rich phases, it can potentially be processed into cementitious material and can be used for a construction purpose. This research investigated the synthesis of nanoferrite (NF) clinker by using red mud as a raw material through chemical combustion technology for potential use in cement-based composite. Before the synthesis of NF, red mud was characterized by using XRF, XRD, and SEM techniques. From characterization results, the stoichiometric ratio of raw materials was calculated and experimentally optimized. The sample was then tested at various temperatures (815, 900, 1000, and 1100°C) to find the optimum synthesis temperature. Finally, the hydraulic activity of NF was verified and the contribution to mechanical properties was determined by replacing cement with NF at various substitution levels (0, 5, 10, and 20 wt%). Test results showed that the optimum condition for the synthesis of NF was found when the ratio of CaCO3/red mud was 1.5 and the sintering temperature was 815°C. The synthesized NF had an average diameter of 300 nm, and the main composition was brownmillerite (C4AF) with distinct hydraulic reaction. When NF was used as a substitute of Portland cement in mortar, the flexural strength with a 5% replacement level improved by 15%. Therefore, it can be concluded that the synthesis of NF provides an alternative approach to recycle red mud and could significantly help in reducing environmental pollution.
- Published
- 2019
- Full Text
- View/download PDF
95. Monitoring and Interpreting the Early Properties of Alkali-Activated Materials by Electrical Conductivity Measurement
- Author
-
Luping Tang, Emma Qingnan Zhang, and Jun Liu
- Subjects
Materials science ,020502 materials ,0211 other engineering and technologies ,02 engineering and technology ,Conductivity ,law.invention ,Portland cement ,0205 materials engineering ,law ,Electrical resistivity and conductivity ,021105 building & construction ,Alkali activated ,Mortar ,Composite material - Abstract
Alkali-activated materials are attracting more and more attention worldwide thanks to their low carbon footprint. Different from the binders based on ordinary Portland cement, the early properties such as flowability, setting, and early strength development, of alkali-activated materials can vary very much and are very sensitive to the compositions of concrete mixture. Conventional methods for testing such early properties are often time-consuming and laborious, whilst the measurement of electrical conductivity is relatively simple and can easily be monitored in an automatic manner. This paper presents a simple monitoring technique based on Winner’s resistivity method and some results measured from mortar samples with various compositions of alkali-activated materials as well as ordinary Portland cements. The preliminary results show some reasonable correlations between monitored conductivity curves and measured/observed early properties. Some interpretations and theoretical considerations to these measured conductivity curves in relation to the early properties and possible chemical reactions are discussed
- Published
- 2019
96. Application of CFRP as anode in cathodic protection for steel reinforced concrete – a review
- Author
-
Luping Tang and Emma Qingnan Zhang
- Subjects
Carbon fiber reinforced polymer ,Materials science ,020209 energy ,0211 other engineering and technologies ,chemistry.chemical_element ,02 engineering and technology ,Reinforced concrete ,Anode ,Corrosion ,Cathodic protection ,chemistry ,lcsh:TA1-2040 ,021105 building & construction ,0202 electrical engineering, electronic engineering, information engineering ,Composite material ,lcsh:Engineering (General). Civil engineering (General) ,Titanium - Abstract
Impressed current cathodic protection (ICCP) is an electrochemical method to prevent or stop corrosion of steel reinforcement in concrete structures. The use of this technique is limited although it has been proven to be effective. One of the reasons is the high cost of anode material, commonly titanium anode. Hence there is a need for alternative anode materials to lower the cost and at the same time to improve the performance of the ICCP system through design. This paper reviews carbon fiber reinforced polymer (CFRP) as an anode for ICCP systems in concrete and discusses the degradation mechanism and operating conditions of the anode. It also gives an overview of the performance of CFRP as an anode material, from laboratory experiments to field operation.
- Published
- 2019
97. In Situ Observation of Crystalline Silicon Growth from SiO2 at Atomic Scale
- Author
-
Hui Zhang, Luping Tang, Tao Xu, Litao Sun, Xing Wu, Kaihao Yu, Qiubo Zhang, and Wen Wang
- Subjects
Multidisciplinary ,Materials science ,Science ,Nanoparticle ,Nanotechnology ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Atomic units ,0104 chemical sciences ,Amorphous solid ,Nanomaterials ,Cathode ray ,Electron beam processing ,Crystalline silicon ,Irradiation ,0210 nano-technology - Abstract
The growth of crystalline Si (c-Si) via direct electron beam writing shows promise for fabricating Si nanomaterials due to its ultrahigh resolution. However, to increase the writing speed is a major obstacle, due to the lack of systematic experimental explorations of the growth process and mechanisms. This paper reports a systematic experimental investigation of the beam-induced formation of c-Si nanoparticles (NPs) from amorphous SiO 2 under a range of doses and temperatures by in situ transmission electron microscopy at the atomic scale. A three-orders-of-magnitude writing speed-up is identified under 80 keV irradiation at 600°C compared with 300 keV irradiation at room temperature. Detailed analysis reveals that the self-organization of c-Si NPs is driven by reduction of c-Si effective free energy under electron irradiation. This study provides new insights into the formation mechanisms of c-Si NPs during direct electron beam writing and suggests methods to improve the writing speed.
- Published
- 2019
98. Influence of moisture content on the contact-hardening properties of calcium silicate hydrate by direct compression
- Author
-
Shuping Wang, Luping Tang, Xiaoqin Peng, Lu Zeng, and Guangxiang Ji
- Subjects
Materials science ,Moisture ,0211 other engineering and technologies ,Compaction ,020101 civil engineering ,02 engineering and technology ,Building and Construction ,Bulk density ,Surface energy ,0201 civil engineering ,chemistry.chemical_compound ,Compressive strength ,chemistry ,Flexural strength ,021105 building & construction ,General Materials Science ,Calcium silicate hydrate ,Composite material ,Water content ,Civil and Structural Engineering - Abstract
The purpose of this study is to investigate the influence of moisture content on the contact-hardening properties of calcium silicate hydrate. The materials with moisture content ranging from 0 to 76% were directly compressed at the pressure of 40 MPa for three minutes to produce solid compacts. Bulk density, mechanical strength and water-resistant property of the compacts were measured, and temperature evolution of the powders during compaction was evaluated. An obvious increase in bulk density of compacts but a slight decrease in compressive strength was found with moisture content increased up to approximately 25%, ascribed to the lubricant effect of water films on the surface of particles that facilitates the rearrangement and spillage of particles. Moisture could reduce the temperature evolution by reducing surface energy of the particles, and separate the interparticulate bonding. Consequently, for the material with moisture content higher than 25%, the bulk density of the compacts was almost constant, but the compressive strength decreased dramatically. Different tendency was observed in the flexural strength that the value increased with moisture content increased up to 11%, attributed to the consolidation of particles and formation of hydrogen bonding, and the water- resistant property of the compacts was also improved. Subsequent decrease in flexural strength was due to the disruption of hydrogen bonding.
- Published
- 2021
99. Shiqi herbal tea reduces the susceptibility to A/M/1/47(H1N1) influenza of mice loaded with restraint stress
- Author
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Zhuo Luo, Guo Xie, LuPing Tang, LiHang Zhang, LiHua Peng, Ling Jin, Hiroshi Kurihara, JinLe Cheng, YiFang Li, and RongRong He
- Published
- 2021
100. Activation of municipal solid waste incineration ashes for green concrete
- Author
-
Luping Tang, Emma Qingnan Zhang, Sara López Menéndez, and Arnaud Glikson
- Subjects
Cement ,Inert ,Waste management ,Municipal solid waste incineration ,technology, industry, and agriculture ,Environmental science ,Test method ,Cementitious ,Pozzolan ,Reuse ,PARTICLE SIZE REDUCTION - Abstract
Due to the variable characteristics of municipal solid waste incineration (MSWI) ashes and the lack of coherent standards and regulations, a majority of MSWI ashes is landfilled currently. It is an urgent issue that the significant amount of residue MSWI ashes need to be better handled and reused as a renewable source. MSWI ashes have great potential to be utilized as a cementitious replacement material in concrete mixing, which is beneficial for both promoting MSWI ash reuse and reducing cement consumption. However, there are major challenges associated with MSWI ash reuse, including the presence of lack of efficient approach to restore the reactivity of MSWI ashes as a binding agent, because such ashes are usually low in reactivity or even inert. This study aims to develop an effective and reliable activation method to enable the pozzolanic and hydraulic properties of MSWI ashes. A novel activation methodology by means of physiochemical treatments, including particle size reduction and high pH activator was proposed to increase the reactivity of such bottom ashes. A rapid test method, namely solution test, was developed to test the potential reactivity after the activation. Thermogravimetric analysis (TGA) and ion chromatography (IC) were employed to evaluate the degree of reactivity. The results showed that the physicochemical treatment can indeed increase the reactivity of MSWI ashes. Compared to the existing test protocols using normal activator the new solution test can more effectively examine the latent pozzolanic activities of MSWI ashes. The successful application of the proposed activation methodology together with the developed solution test could turn those “inert or low reactivity” to-be-landfilled ashes into an active binding agent as a cement replacement material, which would contribute greatly to recycle and reuse of waste materials and reduce CO2 emission.
- Published
- 2020
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