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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    

Enhanced performance of oxygen vacancies on CO adsorption and activation over different phases of ZrO

《能源前沿(英文)》 2023年 第17卷 第4期   页码 545-554 doi: 10.1007/s11708-023-0867-7

摘要: The effect of oxygen vacancies on the adsorption and activation of CO2 on the surface of different phases of ZrO2 is investigated by density functional theory (DFT) calculations. The calculations show that the oxygen vacancies contribute greatly to both the adsorption and activation of CO2. The adsorption energy of CO2 on the c-ZrO2, t-ZrO2 and, m-ZrO2 surfaces is enhanced to 5, 4, and 3 folds with the help of oxygen vacancies, respectively. Moreover, the energy barrier of CO2 dissociation on the defective surfaces of c-ZrO2, t-ZrO2, and m-ZrO2 is reduced to 1/2, 1/4, and 1/5 of the perfect surface with the assistance of oxygen vacancies. Furthermore, the activation of CO2 on the ZrO2 surface where oxygen vacancies are present, and changes from an endothermic reaction to an exothermic reaction. This finding demonstrates that the presence of oxygen vacancies promotes the activation of CO2 both kinetically and thermodynamically. These results could provide guidance for the high-efficient utilization of CO2 at an atomic scale.

关键词: CO2 activation     oxygen vacancies     ZrO2     different phases    

Extending blending proportions of ordinary Portland cement and calcium sulfoaluminate cement blends:

《结构与土木工程前沿(英文)》 2021年 第15卷 第5期   页码 1249-1260 doi: 10.1007/s11709-021-0770-4

摘要: This study extended blending proportion range of ordinary Portland cement (OPC) and calcium sulfoaluminate (CSA) cement blends, and investigated effects of proportions on setting time, workability, and strength development of OPC-CSA blend-based mixtures. Thermogravimetric analysis (TGA) and X-ray diffraction (XRD) were conducted to help understand the performance of OPC-CSA blend-based mixtures. The setting time of the OPC-CSA blends was extended, and the workability was improved with increase of OPC content. Although the early-age strength decreased with increase of OPC content, the strength development was still very fast when the OPC content was lower than 60% due to the rapid formation and accumulation of ettringite. At 2 h, the OPC-CSA blend-based mortars with OPC contents of 0%, 20%, 40%, and 60% achieved the unconfined compressive strength (UCS) of 17.5, 13.9, 9.6, and 5.0 MPa, respectively. The OPC content had a negligible influence on long-term strength. At 90 d, the average UCS of the OPC-CSA blend-based mortars was 39.2 ± 1.7 MPa.

关键词: calcium sulfoaluminate cement     cement blends     hydration reaction     setting     workability     compressive strength    

Optimising the oil phases of aluminium hydrogel-stabilised emulsions for stable, safe and efficient vaccine

《化学科学与工程前沿(英文)》 2022年 第16卷 第6期   页码 973-984 doi: 10.1007/s11705-021-2123-1

摘要: To increase antibody secretion and dose sparing, squalene-in-water aluminium hydrogel (alum)-stabilised emulsions (ASEs) have been developed, which offer increased surface areas and cellular interactions for higher antigen loading and enhanced immune responses. Nevertheless, the squalene (oil) in previous attempts suffered from limited oxidation resistance, thus, safety and stability were compromised. From a clinical translational perspective, it is imperative to screen the optimal oils for enhanced emulsion adjuvants. Here, because of the varying oleic to linoleic acid ratio, soybean oil, peanut oil, and olive oil were utilised as oil phases in the preparation of aluminium hydrogel-stabilised squalene-in-water emulsions, which were then screened for their stability and immunogenicity. Additionally, the underlying mechanisms of oil phases and emulsion stability were unravelled, which showed that a higher oleic to linoleic acid ratio increased anti-oxidative capabilities but reduced the long-term storage stability owing to the relatively low zeta potential of the prepared droplets. As a result, compared with squalene-in-water ASEs, soybean-in-water ASEs exhibited comparable immune responses and enhanced stability. By optimising the oil phase of the emulsion adjuvants, this work may offer an alternative strategy for safe, stable, and effective emulsion adjuvants.

关键词: pickering emulsion     vaccine adjuvant     alum-stabilised emulsion     oleic to linoleic acid ratio     stability    

ITZ microstructure, thickness, porosity and its relation with compressive and flexural strength of cementmortar; influence of cement fineness and water/cement ratio

《结构与土木工程前沿(英文)》 2022年 第16卷 第2期   页码 191-201 doi: 10.1007/s11709-021-0792-y

摘要: A new insight into the interfacial transition zone (ITZ) in cement mortar specimens (CMSs) that is influenced by cement fineness is reported. The importance of cement fineness in ITZ characterizations such as morphology and thickness is elucidated by backscattered electron images and by consequences to the compressive (Fc) and flexural strength (Ff), and porosity at various water/cement ratios. The findings indicate that by increasing the cement fineness the calcium silicate hydrate formation in the ITZ is favored and that this can refine the pore structures and create a denser and more homogeneous microstructure. By increasing cement fineness by about 25% of, the ITZ thickness of CMSs was reduced by about 30% and Fc was increased by 7%–52% and Ff by 19%–40%. These findings illustrate that the influence of ITZ features on the mechanical strength of CMSs is mostly related to the cement fineness and ITZ microstructure.

关键词: cement fineness     interfacial transition zone     compressive and flexural strength    

Study of bond strength between various grade of Ordinary Portland Cement (OPC) and Portland PozzolaneCement (PPC) mixes and different diameter of TMT bars by using pullout test

A D POFALE, S P WANJARI

《结构与土木工程前沿(英文)》 2013年 第7卷 第1期   页码 39-45 doi: 10.1007/s11709-013-0193-y

摘要: Since last two decades, the Portland Pozzolane Cement (PPC) is extensively used in structural concrete. But, till to date, a few literature is available on bond strength of concrete using PPC mixes. There are many literatures available on bond strength of concrete mixes using Ordinary Portland Cement (OPC). Hence, a comparative study was conducted on bond strength between OPC and PPC mixes. In the present investigation, total 24 samples consisting of M20, M35 and M50 grades of concrete and 16 and 25 mm diameter of TMT bar were tested for 7 and 28 days. The pullout bond test was conducted on each specimen as per IS: 2770-1967/1997 [1] and the results were observed at 0.25 mm slip at loaded end called as critical bond stress and at maximum bond load called as maximum bond stress. It was observed that the critical bond strength of PPC mixes is 10% higher than OPC mixes. Whereas, marginal improvement was noticed in maximum bond strength of PPC mixes. Hence, based on these findings, it could be concluded that development length for PPC mixes could be reduced by 10% as compared with same grade of OPC mixes.

关键词: bond strength     Portland Pozzolane Cement (PPC) concrete     Ordinary Portland Cement (OPC) concrete     bond between concrete and steel     pullout test     development length    

Autogenous healing mechanism of cement-based materials

《结构与土木工程前沿(英文)》   页码 948-963 doi: 10.1007/s11709-023-0960-3

摘要: Autogenous self-healing is the innate and fundamental repair capability of cement-based materials for healing cracks. Many researchers have investigated factors that influence autogenous healing. However, systematic research on the autogenous healing mechanism of cement-based materials is lacking. The healing process mainly involves a chemical process, including further hydration of unhydrated cement and carbonation of calcium oxide and calcium hydroxide. Hence, the autogenous healing process is influenced by the material constituents of the cement composite and the ambient environment. In this study, different factors influencing the healing process of cement-based materials were investigated. Scanning electron microscopy and optical microscopy were used to examine the autogenous healing mechanism, and the maximum healing capacity was assessed. Furthermore, detailed theoretical analysis and quantitative detection of autogenous healing were conducted. This study provides a valuable reference for developing an improved healing technique for cement-based composites.

关键词: autogenous healing     cement-based materials     healing mechanism     aggregation effect    

Toxic effects of wastewater from various phases of monosodium glutamate production on seed germination

LIU Rui, ZHOU Qixing, ZHANG Lanying, GUO Hao

《环境科学与工程前沿(英文)》 2007年 第1卷 第1期   页码 114-119 doi: 10.1007/s11783-007-0021-5

摘要: To make a comprehensive assessment on monosodium glutamate (MSG) wastewater pollution, a pollution exposure experiment was carried out on the seed germination and root elongation of wheat, Chinese cabbage and tomato by using the wastewater discharged from different processing phases of MSG production. The results showed that there were significantly positive linear relationships between the inhibitory rates of wheat seed germination and root elongation and the COD of the mother liquor scraps. The toxicity of MSG wastewater to the test crops was in the order of tomato > Chinese cabbage > wheat, indicating that tomato was the most sensitive to the wastewater, and could be considered as an ideal toxic bioindicator. The half-effect concentrations (IC) based on the seed germination and root elongation of the test crops exposed to the wastewater discharged from various processing phases of MSG production was 22.0 32 432 and 17.3 3320 mg/L, respectively.

关键词: monosodium glutamate     different     inhibitory     pollution exposure     half-effect    

Research review of the cement sand and gravel (CSG) dam

Xin CAI, Yingli WU, Xingwen GUO, Yu MING

《结构与土木工程前沿(英文)》 2012年 第6卷 第1期   页码 19-24 doi: 10.1007/s11709-012-0145-y

摘要: The cement sand and gravel (CSG) dam is a new style of dam that owes the advantages both of the concrete faced rock-fill dam (CRFD) and roller compacted concrete (RCC) gravity dam, because of which it has attracted much attention of experts home and abroad. At present, some researches on physic-mechanical property of CSG material and work behavior of CSG dam have been done. This paper introduces the development and characteristics of CSG dam systematically, and summarizes the progress of the study on basic tests, constitutive relation of CSG material and numerical analysis of CSG dam, in addition, indicates research and application aspect of the dam.

关键词: cement sand and gravel (CSG) dam     cement sand and gravel (CSG) material     research review    

Experimental study and field application of calcium sulfoaluminate cement for rapid repair of concrete

Yanhua GUAN, Ying GAO, Renjuan SUN, Moon C. WON, Zhi GE

《结构与土木工程前沿(英文)》 2017年 第11卷 第3期   页码 338-345 doi: 10.1007/s11709-017-0411-0

摘要: The fast-track repair of deteriorated concrete pavement requires materials that can be placed, cured, and opened to the traffic in a short period. Type III cement and Calcium Sulfoaluminate (CSA) cement are the most commonly used fast-setting hydraulic cement (FSHC). In this study, the properties of Type III and CSA cement concrete, including compressive strength, coefficient of thermal expansion (CTE) and shrinkage were evaluated. The test results indicate that compressive strength of FSHC concrete increased rapidly at the early age. CSA cement concrete had higher early-age and long term strength. The shrinkage of CSA cement concrete was lower than that of Type III cement concrete. Both CSA and Type III cement concrete had similar CTE values. Based on the laboratory results, the CSA cement was selected as the partial-depth rapid repair material for a distressed continuously reinforced concrete pavement. The data collected during and after the repair show that the CSA cement concrete had good short-term and long-term performances and, therefore, was suitable for the rapid repair of concrete pavement.

关键词: Calcium Sulfoaluminate (CSA) cement     Type III cement     coefficient of thermal expansion (CTE)     shrinkage     rapid repair    

Multiscale mechanical modeling of hydrated cement paste under tensile load using the combined DEM-MD

Yue HOU, Linbing WANG

《结构与土木工程前沿(英文)》 2017年 第11卷 第3期   页码 270-278 doi: 10.1007/s11709-017-0408-8

摘要: In this paper, a combined DEM-MD method is proposed to simulate the crack failure process of Hydrated Cement Paste (HCP) under a tensile force. A three-dimensional (3D) multiscale mechanical model is established using the combined Discrete Element Method (DEM)-Molecular Dynamics (MD) method in LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator). In the 3D model, HCP consists of discrete particles and atoms. Simulation results show that the combined DEM-MD model is computationally efficient with good accuracy in predicting tensile failures of HCP.

关键词: hydrated cement paste     multiscale     MD simulation     DEM    

Mechanical properties and microstructure of multilayer graphene oxide cement mortar

《结构与土木工程前沿(英文)》 2021年 第15卷 第4期   页码 1058-1070 doi: 10.1007/s11709-021-0747-3

摘要: This study reports on the effects of multilayer graphene oxide (MGO) on compressive strength, flexural strength, and microstructure of cement mortar. The cement mortar was prepared with type P. II. 52.5 Portland cement, standard sand, and MGO. Four mixes were prepared with inclusion of MGO (0%, 0.02%, 0.04%, and 0.06% by weight of cement). The testing result shows that the compressive of GO-cement mortar increased by 4.84%–13.42%, and the flexural strength increased by 4.37%–8.28% at 3 d. GO-cement mortar’s compressive strength and flexural strength at 7 d increased by 3.84%–12.08% and 2.54%–13.43%, respectively. MGO made little contribution to the increases of compressive strength and flexural strength of cement mortar at 28 d. The results of X-ray diffraction (XRD), scanning electron microscope (SEM), and nitrogen (N2) adsorption/desorption tests show that the types of hydration products and crystal grain size did not change after adding MGO. Still, it can help to improve the microstructure of the cement mortar via regulating hydration products and can provide more condensed cores to accelerate hydration. Furthermore, the regulating action of MGO for the microstructure of cement mortar at an early age was better than that at 28 d.

关键词: graphene oxide     cement     mortar     mechanical properties     microstructure    

insights into nitrogen and sulfur co-doped carbon nanotubes for effective desulfurization of liquid phases

《环境科学与工程前沿(英文)》 2021年 第15卷 第5期 doi: 10.1007/s11783-021-1397-3

摘要:

• Synthesis of NS-CNTS is used in a high desulfurization performance.

关键词: Dibenzothiophene (DBT)     Tertiary methyl mercaptan     Adsorption     Carbon nano tube (CNT)     Desulfurization     Doping    

Dynamics of foot-and-mouth disease virus replication in cells at different phases of the cell-division

Claudia DOEL,Zhidong ZHANG,Lise MAZELET,Ryan WATERS,John BASHIRUDDIN

《农业科学与工程前沿(英文)》 2014年 第1卷 第3期   页码 250-257 doi: 10.15302/J-FASE-2014031

摘要: Foot-and-mouth-disease virus (FMDV) replicates in epithelial cells. The restriction of FMDV RNA to the basal cell layer of epithelia suggests a possible link between FMDV replication and the cell status. This paper describes studies in which FMDV infection was investigated in cells that were held at various cell division phases using cell cycle inhibitors. The results suggest that when cells were arrested at the G or G /S phase, high levels of viral RNA were detected by quantitative real-time reverse transcription PCR and viral protein synthesis was observed by specific labeling techniques. In contrast, when cells were arrested at the G /M phase, reduced or no viral RNA synthesis was detected.

关键词: foot-and-mouth disease virus     cell cycle     replication    

Silicon carbide waste as a source of mixture materials for cement mortar

Zhengwu Jiang, Qiang Ren, Haoxin Li, Qing Chen

《环境科学与工程前沿(英文)》 2017年 第11卷 第5期 doi: 10.1007/s11783-017-0974-y

摘要: This paper presents an investigation of the feasibility of recycling silicon carbide waste (SCW) as a source of mixture materials in the production of cement mortar. Mortars with SCW were prepared by replacing different amounts of cement with SCW, and the properties of the resulting mortars, such as the fluidity, strength and shrinkage, were studied in this work. Thermogravimetry-differential scanning calorimetry and scanning electron microscopy were employed to understand the reasons for the property changes of the mortars. The results indicate that SCW decreases the initial and 1-h fluidity of fresh mortar but improves the loss of fluidity. The mortar with SCW exhibits a lower strength at 3 d and 7 d but a higher strength at 28 d and 56 d compared to the control. The shrinkage rate of cement mortar with SCW shows an obvious decrease as the replacement ratio increases. In addition, the content of calcium hydroxide in hardened paste also shows that SCW has some impact on the hydration of the cement-SCW system. The microstructures of the hardened paste also show evidence for a later strength change of mortar containing SCW. This work provides a strategic reference for possibly applying SCW as a mixture material in the production of cement mortar.

关键词: Silicon carbide waste     Cement mortar     Fluidity     Strength     Shrinkage    

标题 作者 时间 类型 操作

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

Enhanced performance of oxygen vacancies on CO adsorption and activation over different phases of ZrO

期刊论文

Extending blending proportions of ordinary Portland cement and calcium sulfoaluminate cement blends:

期刊论文

Optimising the oil phases of aluminium hydrogel-stabilised emulsions for stable, safe and efficient vaccine

期刊论文

ITZ microstructure, thickness, porosity and its relation with compressive and flexural strength of cementmortar; influence of cement fineness and water/cement ratio

期刊论文

Study of bond strength between various grade of Ordinary Portland Cement (OPC) and Portland PozzolaneCement (PPC) mixes and different diameter of TMT bars by using pullout test

A D POFALE, S P WANJARI

期刊论文

Autogenous healing mechanism of cement-based materials

期刊论文

Toxic effects of wastewater from various phases of monosodium glutamate production on seed germination

LIU Rui, ZHOU Qixing, ZHANG Lanying, GUO Hao

期刊论文

Research review of the cement sand and gravel (CSG) dam

Xin CAI, Yingli WU, Xingwen GUO, Yu MING

期刊论文

Experimental study and field application of calcium sulfoaluminate cement for rapid repair of concrete

Yanhua GUAN, Ying GAO, Renjuan SUN, Moon C. WON, Zhi GE

期刊论文

Multiscale mechanical modeling of hydrated cement paste under tensile load using the combined DEM-MD

Yue HOU, Linbing WANG

期刊论文

Mechanical properties and microstructure of multilayer graphene oxide cement mortar

期刊论文

insights into nitrogen and sulfur co-doped carbon nanotubes for effective desulfurization of liquid phases

期刊论文

Dynamics of foot-and-mouth disease virus replication in cells at different phases of the cell-division

Claudia DOEL,Zhidong ZHANG,Lise MAZELET,Ryan WATERS,John BASHIRUDDIN

期刊论文

Silicon carbide waste as a source of mixture materials for cement mortar

Zhengwu Jiang, Qiang Ren, Haoxin Li, Qing Chen

期刊论文