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8. Carbonation of 20-year-old blended cement pastes

Author

Li, Shuangxin

Subjects
628.74
Abstract

This PhD study aims to understand the carbonation mechanism of slag-rich waste forms and consequently benefits assessing the long term efficiency of immobilising waste materials with cementitious disposals. Three phases of experiments had been managed to achieve the aim. The first was an examination of three 20-year-old alkali-activated neat slag pastes. This section supplied the information about the immobilisation mechanism of alkaline metal cations within a cement system. The second was a characterisation of four 20-year-old water- activated slag-bearing pastes with curing at 40°C for the initial five years. This part concerned the effects of aging and heating treatment in cement hydration. The third was the accelerated and gentle testing of the water-activated pastes. The carbonation mechanism was mainly drawn by the micro-structural and nano- structural features of carbonated pastes and comparison to those of hydrated pastes. The obtained experimental data for the alkali-activated pastes confirmed the outstanding suitability of slag for fixing metal cations. It was because the formed C- S-H gel had been verified to be entirely tobermorite-based and possess a high substitution degree of bridging Si tetrahedra by Al tetrahedra. Meanwhile, the main fixation mechanism has been proved to be the incorporation of metal cations into the structure of the C-S-H through balancing the charges caused by the substitution. Thus, the significant incorporation of Ae+ within the structure of the C-S-H could be advantageous of immobilising alkaline cations through charge-balancing. The collapse of the C-S-H structure during carbonation has been observed due to not only decalcification, but also dealumination. Thus, according to the above findings, the carbonation is very likely to negatively affect the fixation of waste materials within cement systems. It was because, along with the extraction of the bridging Al tetrahedra, the charge-balancing cations were not needed and possibly would eventually be released. A conceptual model of carbonation occurring in hardened cement pastes has been proposed at the end of the chapter conclusion. More findings about the efficiency of different activators on hydration and the effects of curing temperature and aging on hydration have been discussed in details in the following chapters.

Published
2012

9. Association of Objective Sleep Characteristics and Incident Angina Pectoris: A Longitudinal Analysis from the Sleep Heart Health Study

Author

Liu,Jiali, Zhu,Yuanqiang, Chang,Yingjuan, Xu,Ziliang, Wang,Chen, Zhang,Pengpeng, Li,Shuangxin, Yang,Wenxuan, An,Rui, Wen,Didi, Xu,Jian, Zheng,Minwen, Liu,Jiali, Zhu,Yuanqiang, Chang,Yingjuan, Xu,Ziliang, Wang,Chen, Zhang,Pengpeng, Li,Shuangxin, Yang,Wenxuan, An,Rui, Wen,Didi, Xu,Jian, and Zheng,Minwen

Abstract

Jiali Liu,1,* Yuanqiang Zhu,1,* Yingjuan Chang,1,* Ziliang Xu,1 Chen Wang,1 Pengpeng Zhang,1 Shuangxin Li,1 Wenxuan Yang,1 Rui An,1,2 Didi Wen,1 Jian Xu,1,2 Minwen Zheng1 1Department of Radiology, Xijing Hospital, Air Force Medical University, Xi’an, Shaanxi, People’s Republic of China; 2Department of Interventional Surgery Center, Xijing Hospital, Air Force Medical University, Xi’an, Shaanxi, People’s Republic of China*These authors contributed equally to this workCorrespondence: Minwen Zheng, Department of Radiology, Xijing Hospital, Air Force Medical University, 127# Changle West Road, Xi’an, Shaanxi, 710032, People’s Republic of China, Tel +86-29-84775421, Fax +86-29-84773732, Email zhengmw2007@163.com Jian Xu, Department of Interventional Surgery Center, Xijing Hospital, Air Force Medical University, 127# Changle West Road, Xi’an, Shaanxi, 710032, People’s Republic of China, Tel +86-29-84775299, Fax +86-29-84775299, Email xujian771939@163.comPurpose: While prior research has highlighted a significant association between sleep characteristics and angina pectoris (AP) incidence, the link between sleep efficiency (SE) and angina remains unexplored. This study seeks to elucidate the relationship between AP and objectively quantified SE.Patients and Methods: We examined a cohort of 2990 participants (1320 males and 1670 females; mean age 63.69 ± 13.2 years) from the Sleep Heart Health Study. The main exposure variable was SE, as determined by baseline home polysomnography, while the primary outcome was the first incidence of angina pectoris (AP) during the period between the baseline polysomnography and the end of follow-up. A multivariate Cox regression model was utilized, controlling for factors such as age, gender, BMI, smoking and alcohol consumption habits, diabetes, hypertension, sleep duration, triglycerides, cholesterol, high-density lipoprotein, apnea-hypopnea index, nocturnal oxygen saturatio

Published
2023

14. Preparation, morphology and properties of natural rubber/carbon black/multi-walled carbon nanotubes conductive composites

Author

Xuefeng Ta, Li Yu, Jun Xu, and Li Shuangxin

Subjects
Materials science, 02 engineering and technology, Carbon nanotube, 010402 general chemistry, 01 natural sciences, law.invention, chemistry.chemical_compound, Natural rubber, law, Electrical and Electronic Engineering, Composite material, Tear resistance, Vulcanization, Dynamic mechanical analysis, Carbon black, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Atomic and Molecular Physics, and Optics, 0104 chemical sciences, Electronic, Optical and Magnetic Materials, chemistry, visual_art, Masterbatch, visual_art.visual_art_medium, 0210 nano-technology, Glass transition
Abstract

Nature rubber (NR)/carbon black (CB)/multi-walled carbon nanotubes (MWNTs) electrical conductive composites were prepared through latex compounding technique assisted by anionic surfactants containing phenyl ring moieties, NR/MWNTs masterbatch treated with silane coupling agent containing polysulphide bond and mixed with commercial NR, CB, sulphur and other ingredients and vulcanization. When MWNTs were dispersed in sodium dodecylbenzene sulfonate (SDBS) water solution, SDBS assembly on the surface of MWNTs prevent aggregation of MWNTs in water forming a stable MWNTs suspension. After MWNTs suspension mixed with NR latex, NR-MWNTs latex compound was co-coagulated to obtain the well dispersed NR/MWNTs masterbatch. In order to strengthen interface bonding between MWNTs and NR matrix, MWNTs in the masterbatch were treated with silane coupling agent by melt mixing process. During rubber mixing process, MWNTs dispersed in masterbatch thoroughly mixed with all the components and MWNTs homogenously embedded in NR matrix. Owing to homogenous dispersion of MWNTs, interfacial bonding between MWNTs and NR matrix as well as synergistic reinforcing effect between MWNTs and CB, NR/CB/MWNTs composites exhibited improved mechanical properties, dynamical storage modulus, glass transition temperature, electrical and thermal conductivity. Tensile strength, stress at 300 % strain, tear strength and steady state thermal conductivity of NR/CB/MWNTs composite with 4 phr MWNTs loading were increased by 12.36, 26.02, 16.95 and 102 %, respectively, and volume resistivity at room temperature of the composite was decreased by four orders of magnitude compared with NR/CB composite.

Published
2016

17. A microstructural and compositional investigation of 20-year-old neat and blended slag samples hydrated at 40 degrees C.

Author

Li Shuangxin, 29th Cement and concrete science conference Leeds, UK 07-Sep-0908-Sep-09 Session 1, paper 2. Institute of Materials, Minerals and Mining, Brydson R.M.D., Richardson I.G., Williams S., Li Shuangxin, 29th Cement and concrete science conference Leeds, UK 07-Sep-0908-Sep-09 Session 1, paper 2. Institute of Materials, Minerals and Mining, Brydson R.M.D., Richardson I.G., and Williams S.

Abstract

The use of blast-furnace slag with ordinary Portland cement for the encapsulation of intermediate-level radioactive wastes was investigated using samples that had been cured for 6 years at 40 degrees C, then stored at room temperature for 14 years. Curing at 40 degres C gave hydration products with some differences from those obtained at 25 degrees C in terms of morphology, microstructure and composition. The effects on the hydration products of the amount of slag were also considered by comparing the results for different samples., The use of blast-furnace slag with ordinary Portland cement for the encapsulation of intermediate-level radioactive wastes was investigated using samples that had been cured for 6 years at 40 degrees C, then stored at room temperature for 14 years. Curing at 40 degres C gave hydration products with some differences from those obtained at 25 degrees C in terms of morphology, microstructure and composition. The effects on the hydration products of the amount of slag were also considered by comparing the results for different samples.

Published
2009

18. Preparation of multi-colored binary silica supraballs and color fine-tuning based on color mixing.

Author

Li S, Yang C, Liu Y, and Wang G

Abstract

Structural colors are highly valued for their eco-friendliness and long-term color stability, deriving from the interaction of structural units with incident light. However, traditional methods for adjusting structural colors typically involve altering the size of structural units, a labor-intensive process necessitating specific diameters for each desired color. Moreover, colors exhibited by photonic crystal materials are monochromatic colors with a narrow wavelength range, failing to exhibit polychromatic colors. This restricts their practical applications, as they do not accurately represent the actual color of objects themselves. Hence, this study focuses on fabricating binary supraballs can display polychromatic colors. These supraballs consist of two types of structural units with distinct diameter differences. By adjusting the mass ratio between these units within the supraballs, fine color tuning is achievable. Utilizing three different diameters of silica nanospheres, this method enables the fabrication of supraballs with a diverse range of colors spanning nearly the entire visible spectrum. The adjustable colors of these binary supraballs not only enhance their ability to replicate the colors of objects, but also reduce the significant workload involved in preparing the original structural units. The synthesized supraballs are in powder form, directly applicable as coatings, inks, and other materials., Competing Interests: Declaration of Competing Interest We declare that we have no financial or personal relationships with other individuals or organizations that could inappropriately influence our work. Furthermore, we have no professional or personal interests in any product, service, or company that could be perceived as influencing the content or review of the manuscript entitled., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Published
2024
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