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Quantification of hydration products in cementitious materials incorporating silica nanoparticles

L. P. SINGH,A. GOEL,S. K. BHATTACHARYYA,G. MISHRA

《结构与土木工程前沿（英文）》 2016年 第10卷 第2期   页码 162-167 doi: 10.1007/s11709-015-0315-9

摘要： In the present work, silica nanoparticles (30-70nm) were supplemented into cement paste to study their influence on degree of hydration, porosity and formation of different type of calcium-silicate-hydrate (C-S-H) gel. As the hydration time proceeds, the degree of hydration reach to 76% in nano-modified cement paste whereas plain cement achieve up to 63% at 28 days. An influence of degree of hydration on the porosity was also determined. In plain cement paste, the capillary porosity at 1hr is ~48%, whereas in silica nanoparticles added cement is ~35 % only, it revealed that silica nanoparticles refines the pore structure due to accelerated hydration mechanism leading to denser microstructure. Similarly, increasing gel porosity reveals the formation of more C-S-H gel. Furthermore, C-S-H gel of different Ca/Si ratio in hydrated cement paste was quantified using X-ray diffractometer and thermogravimetry. The results show that in presence of silica nanoparticles, ~24% C-S-H (Ca/Si<1.0) forms, leading to the formation of polymerised and compact C-S-H. In case of plain cement this type of C-S-H was completely absent at 28 days. These studies reveal that the hydration mechanism of the cement can be tuned with the incorporation of silica nanoparticles and thus, producing more durable cementitious materials.

关键词： degree of hydration     porosity     calcium-silicate-hydrate (C-S-H)     silica nanoparticles    

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Compressive behavior and microstructure of concrete mixed with natural seawater and sea sand

《结构与土木工程前沿（英文）》 2021年 第15卷 第6期   页码 1347-1357 doi: 10.1007/s11709-021-0780-2

摘要： Noncorrosive reinforcement materials facilitate producing structural concrete with seawater and sea sand. This study investigated the properties of seawater and sea sand concrete (SSC), considering the curing age (3, 7, 14, 21, 28, 60, and 150 d) and strength grade (C30, C40, and C60). The compressive behavior of SSC was obtained by compressive tests and digital image correction (DIC) technique. Scanning electron microscope (SEM) and X-ray powder diffraction (XRD) methods were applied to understand the microstructure and hydration products of cement in SSC. Results revealed a 30% decrease in compressive strength for C30 and C40 SSC from 60 to 150 d, and a less than 5% decrease for C60 from 28 to 150 d. DIC results revealed significant cracking and crushing from 80% to 100% of compressive strength. SEM images showed a more compact microstructure in higher strength SSC. XRD patterns identified Friedel’s salt phase due to the chlorides brought by seawater and sea sand. The findings in this study can provide more insights into the microstructure of SSC along with its short- and long-term compressive behavior.

关键词： seawater and sea sand concrete     compressive strength     strain field     microstructure     hydration products    

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Thermodynamic analysis of ethanol synthesis from hydration of ethylene coupled with a sequential reaction

Jie Gao, Zhikai Li, Mei Dong, Weibin Fan, Jianguo Wang

《化学科学与工程前沿（英文）》 2020年 第14卷 第5期   页码 847-856 doi: 10.1007/s11705-019-1848-6

摘要： Coal-based ethanol production by hydration of ethylene is limited by the low equilibrium ethylene conversion at elevated temperature. To improve ethylene conversion, coupling hydration of ethylene with a potential ethanol consumption reaction was analyzed thermodynamically. Five reactions have been attempted and compared: (1) dehydration of ethanol to ethyl ether ( ), (2) dehydrogenation of ethanol to acetaldehyde ( ), (3) esterification of acetic acid with ethanol ( ), (4) dehydrogenation of ethanol to ethyl acetate ( ), and (5) oxidative dehydrogenation of ethanol to ethyl acetate ( ). The equilibrium constants and equilibrium distributions of the coupled reactions were calculated and the effects of feed composition, temperature and pressure upon the ethylene equilibrium conversion were examined. The results show that dehydrogenation of ethanol to acetaldehyde has little effect on ethylene conversion, whereas for dehydrogenation of ethanol to acetaldehyde and ethyl acetate, ethylene conversion can be improved from 8% to 12.8% and 18.5%, respectively, under conditions of H O/C H = 2, 10 atm and 300°C. The esterification of acetic acid with ethanol can greatly enhance the ethylene conversion to 22.5%; in particular, ethylene can be actually completely converted to ethyl acetate by coupling oxidative dehydrogenation of ethanol.

关键词： ethylene     ethanol     thermodynamics     coupling    

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水泥基材料及其性能的分子模拟研究 Review

Ashraf A. Bahraq, Mohammed A. Al-Osta, Omar S. Baghabra Al-Amoudi, I.B. Obot,Mohammed Maslehuddin, Habib-ur-Rehman Ahmed, Tawfik A. Saleh

《工程（英文）》 2022年 第15卷 第8期   页码 165-178 doi: 10.1016/j.eng.2021.06.023

摘要：

Hydrated cement is one of the complex composite systems due to the presence of multi-scale phases with varying morphologies. Calcium silicate hydrate (C–S–H), which is the principal binder phase in the hydrated cement, is responsible for the stiffness, strength, and durability of Portland cement concrete. To understand the mechanical and durability behavior of concrete, it is important to investigate the interactions of hydrated cement phases with other materials at the nanoscale. In this regard, the molecular simulation of cement-based materials is an effective approach to study the properties and interactions of the cement system at the fundamental scale. Recently, many studies have been published regarding atomistic simulations to investigate the cement phases to define/explain the microscopic physical and chemical properties, thereby improving the macroscopic performance of hardened binders. The research in molecular simulation of cementitious systems involves researchers with multidisciplinary backgrounds, mainly in two areas: ① cement chemistry, where the hydration reactions govern most of the chemical and physical properties at the atomic scale; and ② computational materials science and engineering, where the bottom-up approach is required. The latter approach is still in its infancy, and as such, a study of the prevailing knowledge is useful, namely through an exhaustive literature review. This state-of-the-art report provides a comprehensive survey on studies that were conducted in this area and cites the important findings.

关键词： Atomistic simulation     Molecular dynamics     Cement phases     Hydration products     Nanoengineering    

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Screening of indicator pharmaceuticals and personal care products in landfill leachates: a case study

《环境科学与工程前沿（英文）》 2023年 第17卷 第9期 doi: 10.1007/s11783-023-1716-y

摘要：

● A systematic framework was developed to identify i-PPCPs for landfill leachate.

关键词： Landfill leachates     PPCPs     Indicator     Screening criteria     Source-specificity    

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Hydration, microstructure and autogenous shrinkage behaviors of cement mortars by addition of superabsorbent

Beibei SUN, Hao WU, Weimin SONG, Zhe LI, Jia YU

《结构与土木工程前沿（英文）》 2020年 第14卷 第5期   页码 1274-1284 doi: 10.1007/s11709-020-0656-x

摘要： Superabsorbent Polymer (SAP) has emerged as a topic of considerable interest in recent years. The present study systematically and quantitively investigated the effect of SAP on hydration, autogenous shrinkage, mechanical properties, and microstructure of cement mortars. Influences of SAP on hydration heat and autogenous shrinkage were studied by utilizing TAM AIR technology and a non-contact autogenous shrinkage test method. Scanning Electron Microscope (SEM) was employed to assess the microstructure evolution. Although SAP decreased the peak rate of hydration heat and retarded the hydration, it significantly increased the cumulative heat, indicating SAP helps promote the hydration. Hydration promotion caused by SAP mainly occurred in the deceleration period and attenuation period. SAP can significantly mitigate the autogenous shrinkage when the content ranged from 0 to 0.5%. Microstructure characteristics showed that pores and gaps were introduced when SAP was added. The microstructure difference caused by SAP contributed to the inferior mechanical behaviors of cement mortars treated by SAP.

关键词： Superabsorbent Polymer     mechanical properties     hydration heat     autogenous shrinkage     microstructure    

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Characteristics of typical dissolved black carbons and their influence on the formation of disinfection by-products

《环境科学与工程前沿（英文）》 2022年 第16卷 第12期 doi: 10.1007/s11783-022-1585-9

摘要：

● The physicochemical and structural properties of DBC were characterized.

关键词： Dissolved black carbon (DBC)     Chlorine     Chloramine     Disinfection by-products (DBPs)     Disinfection by-products formation potential (DBPFP)    

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Data quality assessment for studies investigating microplastics and nanoplastics in food products: Are

《环境科学与工程前沿（英文）》 2023年 第17卷 第8期 doi: 10.1007/s11783-023-1694-0

摘要：

● Data quality assessment criteria for MP/NPs in food products were developed.

关键词： Microplastic     Nanoplastic     Food products     Data quality     Human health risk    

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预制拼装箱梁现浇横隔梁水化热分析与控制研究

陈扬,钟瑶,郑开启,沈斌,孟少平

《中国工程科学》 2013年 第15卷 第8期   页码 99-103

摘要：

在节段预制拼装桥梁的墩顶节段，常常采用后浇横隔梁的方式来减轻吊装重量。后浇横隔梁在体量上属于大体积混凝土，混凝土水化热问题会引起一些部位拉应力过大，如控制措施不合理，往往会导致预制梁段在施工阶段的开裂。本文结合南京长江第四大桥的引桥工程，基于三维瞬态温度场理论，利用通用有限元程序ANSYS对墩顶梁段现浇块的水化热效应进行了数值仿真，研究箱梁水化热温度场和应力场的分布规律。分析结果表明，水化热引起的箱梁腹板外侧拉应力水平足以导致混凝土开裂，在水化热测试试验中也观测到了箱梁腹板外侧的纵向微裂缝，与分析相符。在研究水化热温度场和应力场分布规律的基础上，进行了控制水化热温度应力的措施研究，在实桥施工中证实是切实有效的。

关键词： 混凝土箱梁     水化热     温度场     应力场     裂缝    

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Determination and occurrence of endocrine disrupting compounds, pharmaceuticals and personal care products

Yong YU,Laosheng WU

《环境科学与工程前沿（英文）》 2015年 第9卷 第3期   页码 475-481 doi: 10.1007/s11783-014-0640-6

摘要： Endocrine disrupting compounds (EDCs), pharmaceuticals and personal care products (PPCPs) have attracted much attention due to widespread contamination in aquatic environment. In this study, we determined 13 EDCs and PPCPs in fish blood, bile and muscle by using gas chromatography-mass spectrometry (GC-MS). The limits of quantitation (LOQ) were in the ranges of 0.23–2.54, 0.22–2.36 ng·mL , and 0.24–2.57 ng·g dry weight (dw) for fish blood, bile and muscle, respectively. Recoveries of target compounds spiked into sample matrices and passed through the entire analytical procedure ranged from 65% to 95%, from 60% to 92% and from 62% to 91% for blood, bile and muscle, respectively. The methods were applied to the analysis of fish from a lake in California. Target compounds were relatively low in bile, and only bisphenol A (BPA) and diclofenac were measurable near the LOQ. Seven of 13 compounds were detected in blood, with total concentrations up to 39 ng·mL . Only BPA was frequently found in muscle, with mean concentration of 7.26 ng·g dw. The estimated daily intake of BPA through fish consumption for U.S. resident was significantly lower than the tolerable daily intake recommended by the European Food Safety Authority. This study showed that the exposure to the bisphenol A from fish diet is unlikely to pose a health risk.

关键词： endocrine disrupting compounds (EDCs)     pharmaceuticals and personal care products (PPCPs)     fish     bisphenol A (BPA)     risk assessment    

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Integrated risk assessment framework for transformation products of emerging contaminants: what we know

《环境科学与工程前沿（英文）》 2023年 第17卷 第7期 doi: 10.1007/s11783-023-1691-3

摘要：

● A better risk assessment can combine the improved non-target analysis method.

关键词： Risk assessment frameworks     Transformation products     Emerging contaminants     High-throughput toxicity screening     Water treatment    

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Impact and inhibitory mechanism of phenolic compounds on the formation of toxic Maillard reaction products

Jing TENG, Xiaoqian HU, Ningping TAO, Mingfu WANG

《农业科学与工程前沿（英文）》 2018年 第5卷 第3期   页码 321-329 doi: 10.15302/J-FASE-2017182

摘要：

As one of the dominant reactions occurring during thermal treatment of food, the Maillard reaction not only leads to the formation of aroma, browning color and taste compounds, but also contributes to the formation of some unpleasant toxic substances including acrylamide, heterocyclic amines and advanced glycation end products. Polyphenols, one of the most abundant antioxidants in the human diet, are contained in different kinds of foods. In this review, some recent studies on the impact of dietary polyphenols on the formation of acrylamide, heterocyclic amines and advanced glycation end products formed during the Maillard reaction are summarized, including the research work conducted with both chemical model systems and real food model systems; the possible inhibitory mechanisms of different polyphenols are also summarized and discussed in this review. Basically we found that some dietary polyphenols not only scavenge free radicals, but also react with reactive carbonyl species, thus lowering the formation of toxic Maillard reaction products. This review provides a useful theoretical foundation for the application of polyphenols in food safety, and suggests some directions for further study of natural products as inhibitors against the formation of toxic substances in thermally processed food.

关键词： advanced glycation end products     acrylamide     food safety     heterocyclic amine     Maillard reaction     polyphenols    

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Effects of temperature on pyrolysis products of oil sludge

LIU Jianguo, SONG Wei, NIE Yongfeng

《环境科学与工程前沿（英文）》 2008年 第2卷 第1期   页码 8-14 doi: 10.1007/s11783-008-0030-z

摘要： Temperature is the determining factor of pyrolysis, which is one of the alternative technologies for oil sludge treatment. The effects of final operating temperature ranging from 350 to 550°C on pyrolysis products of oil sludge were studied in an externally-heating fixed bed reactor. With an increase of temperature, the mass fraction of solid residues, liquids, and gases in the final product is 67.00%–56.00%, 25.60%–32.35%, and 7.40%–11.65%, and their corresponding heat values are 34.4–13.8 MJ/kg, 44.41–46.6 MJ/kg, and 23.94–48.23 MJ/Nm, respectively. The mass and energy tend to shift from solid to liquid and gas phase (especially to liquid phase) during the process, and the optimum temperature for oil sludge pyrolysis is 500°C. The liquid phase is mainly composed of alkane and alkene (C–C), and the gas phase is dominantly HC and H.

关键词： sludge treatment     corresponding     Temperature     liquid     process    

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Nitrogen distribution in the products from the hydrothermal liquefaction of sp. and sp.

《化学科学与工程前沿（英文）》 2022年 第16卷 第6期   页码 985-995 doi: 10.1007/s11705-021-2126-y

摘要： The high contents of nitrogen-containing organic compounds in biocrude obtained from hydrothermal liquefaction of microalgae are one of the most concerned issues on the applications and environment. In the project, Chlorella sp. and Spirulina sp. were selected as raw materials to investigate the influence of different reaction conditions (i.e., reaction temperature, residence time, solid loading rate) on the distribution of nitrogen in the oil phase and aqueous phase. Three main forms of nitrogen-containing organic compounds including nitrogen-heterocyclic compounds, amide, and amine were detected in biocrudes. The contents of nitrogen-heterocyclic compounds decreased with temperature while amide kept increasing. The effect of residence time on the components of nitrogen-containing organic compounds was similar with that of temperature. However, the influence of solid loading rate was insignificant. Moreover, it was also found that the differences of amino acids in the protein components in the two microalgae might affect the nitrogen distribution in products. For example, nitrogen in basic amino acids of Spirulina sp. preferred to go into the aqueous phase comparing with the nitrogen in neutral amino acids of Chlorella sp. In summary, a brief reaction map was proposed to describe the nitrogen pathway during microalgae hydrothermal liquefaction.

关键词： microalgae     hydrothermal liquefaction     biocrude     nitrogen distribution    

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Effect of a commercial dispersion of multi walled carbon nanotubes on the hydration of an oil well cementing

Ocar Aurelio MENDOZA REALES,William C.PEARL Jr,Maria D. M. PAIVA,CristianeR. MIRANDA,Romildo Dias TOLEDO FILHO

《结构与土木工程前沿（英文）》 2016年 第10卷 第2期   页码 174-179 doi: 10.1007/s11709-015-0324-8

摘要： This work studies the influence of a commercial dispersion of multi wall carbon nanotubes (MWCNT) on the hydration of a class G cement paste, at room and elevated down-hole temperatures. The MWCNT dispersion was produced with a solids concentration of 3.0 % by mass and an anionic surfactant as dispersing agent. Cement pastes with water-to-cement ratio of 0.45 and additions of solid MWCNT by mass of cement up to 0.50 % were studied. Isothermal calorimetry results showed a clear retardation of the hydration of cement caused by the surfactant contained in the MWCNT dispersion. Nevertheless, thermogravimetric evaluations showed that once the hydration reaction resumed, the retardation effect of the surfactant did not have a negative impact on the amount of hydration products precipitated. It was concluded that the commercial MWCNT dispersion presents a good potential to be applied in oil well cement pastes.

关键词： carbon nanotubes     surfactant     retardation     combined water     C-S-H    

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标题 作者 时间 类型 操作

Quantification of hydration products in cementitious materials incorporating silica nanoparticles

L. P. SINGH,A. GOEL,S. K. BHATTACHARYYA,G. MISHRA

期刊论文

Compressive behavior and microstructure of concrete mixed with natural seawater and sea sand

期刊论文

Thermodynamic analysis of ethanol synthesis from hydration of ethylene coupled with a sequential reaction

Jie Gao, Zhikai Li, Mei Dong, Weibin Fan, Jianguo Wang

期刊论文

水泥基材料及其性能的分子模拟研究

Ashraf A. Bahraq, Mohammed A. Al-Osta, Omar S. Baghabra Al-Amoudi, I.B. Obot,Mohammed Maslehuddin, Habib-ur-Rehman Ahmed, Tawfik A. Saleh

期刊论文

Screening of indicator pharmaceuticals and personal care products in landfill leachates: a case study

期刊论文

Hydration, microstructure and autogenous shrinkage behaviors of cement mortars by addition of superabsorbent

Beibei SUN, Hao WU, Weimin SONG, Zhe LI, Jia YU

期刊论文

Characteristics of typical dissolved black carbons and their influence on the formation of disinfection by-products

期刊论文

Data quality assessment for studies investigating microplastics and nanoplastics in food products: Are

期刊论文

预制拼装箱梁现浇横隔梁水化热分析与控制研究

陈扬,钟瑶,郑开启,沈斌,孟少平

期刊论文

Determination and occurrence of endocrine disrupting compounds, pharmaceuticals and personal care products

Yong YU,Laosheng WU

期刊论文

Integrated risk assessment framework for transformation products of emerging contaminants: what we know

期刊论文

Impact and inhibitory mechanism of phenolic compounds on the formation of toxic Maillard reaction products

Jing TENG, Xiaoqian HU, Ningping TAO, Mingfu WANG

期刊论文

Effects of temperature on pyrolysis products of oil sludge

LIU Jianguo, SONG Wei, NIE Yongfeng

期刊论文

Nitrogen distribution in the products from the hydrothermal liquefaction of sp. and sp.

期刊论文

Effect of a commercial dispersion of multi walled carbon nanotubes on the hydration of an oil well cementing

Ocar Aurelio MENDOZA REALES,William C.PEARL Jr,Maria D. M. PAIVA,CristianeR. MIRANDA,Romildo Dias TOLEDO FILHO

期刊论文