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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    

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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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Appraising the potential of calcium sulfoaluminate cement-based grouts in simulated permafrost environments

《结构与土木工程前沿（英文）》 2023年 第17卷 第5期   页码 722-731 doi: 10.1007/s11709-023-0950-5

摘要： The aim of this study is to appraise the potential of calcium sulfoaluminate (CSA) cement-based grouts in simulated permafrost environments. The hydration and performance of CSA cement-based grouts cured in cold environments (10, 0, and −10 °C) are investigated using a combination of tests, including temperature recording, X-ray diffraction (XRD) tests, thermogravimetric analysis (TGA), and unconfined compressive strength (UCS) tests. The recorded temperature shows a rapid increase in temperature at the early stage in all the samples. Meanwhile, results of the TGA and XRD tests show the generation of a significant quantity of hydration products, which indicates the rapid hydration of CSA cement-based grouts at the early stage at low temperatures. Consequently, the CSA cement-based grouts exhibit remarkably high early strength. The UCS values of the samples cured for 2 h at −10, 0, and 10 °C are 6.5, 12.0, and 12.3 MPa, respectively. The UCS of the grouts cured at −10, 0, and 10 °C increases continuously with age and ultimately reached 14.9, 19.0, and 30.6 MPa at 28 d, respectively. The findings show that the strength of grouts fabricated using CSA cement can develop rapidly in cold environments, thus rendering them promising for permafrost applications.

关键词： permafrost     low temperatures     calcium sulfoaluminate cement-based grouts     hydration reaction     compressive strength    

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掺梳形减水剂水泥浆体早期水化产物形貌研究

蒋亚清

《中国工程科学》 2011年 第13卷 第9期   页码 69-75

摘要：

为揭示梳形减水剂对水泥早期水化的影响规律，指导工程应用,通过SEM分析，研究了掺用3种典型结构的梳形减水剂的水泥浆体早期水化产物形貌及其电子特征数据。结果表明，梳形减水剂加速了水泥早期水化反应，且丙烯酸类、马来酸类共聚物分别促进了AFt、AFm的形成。因此，梳形减水剂品种对水泥早期水化和混凝土工程性能具有较大影响，应根据使用要求合理选用，必要时与缓凝剂、引气剂或消泡剂复合使用。

关键词： 梳形减水剂     水泥水化     钙矾石     微观形貌    

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The effect of SiO

Ismael FLORES-VIVIAN, Rani G.K PRADOTO, Mohamadreza MOINI, Marina KOZHUKHOVA, Vadim POTAPOV, Konstantin SOBOLEV

《结构与土木工程前沿（英文）》 2017年 第11卷 第4期   页码 436-445 doi: 10.1007/s11709-017-0438-2

摘要： The nanoparticles of SiO were used in cement systems to modify the rheological behavior, to enhance the reactivity of supplementary cementitious materials, and also to improve the strength and durability. In this research, low-cost nano-SiO particles from natural hydrothermal solutions obtained by membrane ultrafiltration and, optionally, by cryochemical vacuum sublimation drying, were evaluated in portland cement based systems. ??The SiO -rich solutions were obtained from the wells of Mutnovsky geothermal power station (Far East of Russia). The constant nano-SiO dosage of 0.25% (as a solid material by weight of cementitious materials) was used to compare the cement systems with different nanoparticles against a reference mortar and a commercially available nano-SiO . Nanoparticles were characterized by X-Ray Diffraction (XRD), BET Surface Area, Scanning Electron Microscope (SEM) and Fourier Transform Infrared (FTIR) spectroscopy techniques. It was demonstrated that the addition of polycarboxylate ether superplasticizer and the dispersion treatment using an ultrasound processor can be used to facilitate the distribution of nano-SiO particles in the mixing water. The effect of nano-SiO particles in portland cement mortars was investigated by evaluating the flow, heat of hydration and compressive strength development. It was demonstrated that the use of nano-SiO particles can reduce the segregation and improve strength properties.

关键词： ultrafiltration     cryochemical vacuum sublimation drying     nanoparticles     portland cement     heat of hydration     surface area     compressive strength    

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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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Experimental investigation of evolutive mode-I and mode-II fracture behavior of fiber-reinforced cemented paste backfill: Effect of curing temperature and curing time

《结构与土木工程前沿（英文）》 2023年 第17卷 第2期   页码 256-270 doi: 10.1007/s11709-022-0924-z

摘要： The curing temperature-dependent cement hydration causes the nonlinear evolution of fracture behavior and properties of fiber-reinforced cemented paste backfill (CPB) and thus influences the stability of mine backfill materials in deep mines. Therefore, the coupled effect of curing temperature (20, 35, and 45 °C) and cement hydration at different curing times (3, 7, and 28 d) on the mode-I and mode-II fracture behavior and properties of fiber-reinforced CPB is investigated. A comprehensive experimental testing program consisting of semicircular bend tests, direct shear tests, measurement of volumetric water content and matric suction, TG/DTG tests, and SEM observation is carried out. The results show that the coupled thermochemical effect results in strongly nonlinear development of pre- and post-peak behavior of fiber-reinforced CPB. Moreover, the results discover a positive linear correlation between fracture toughness and shear strength parameters and also reveal the vital role played by matric suction in the formation of fracture toughness. Furthermore, predictive functions are developed to estimate the coupled thermochemical effect on the development of KIc and KIIc. Therefore, the findings and the developed mathematical tools have the potential to promote the successful application of fiber-reinforced CPB technology in deep underground mines.

关键词： fiber reinforcement     cemented paste backfill     fracture behavior     underground mine     cement hydration    

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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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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    

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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    

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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    

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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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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    

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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    

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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    

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标题 作者 时间 类型 操作

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

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

Appraising the potential of calcium sulfoaluminate cement-based grouts in simulated permafrost environments

期刊论文

掺梳形减水剂水泥浆体早期水化产物形貌研究

蒋亚清

期刊论文

The effect of SiO

Ismael FLORES-VIVIAN, Rani G.K PRADOTO, Mohamadreza MOINI, Marina KOZHUKHOVA, Vadim POTAPOV, Konstantin SOBOLEV

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

Experimental investigation of evolutive mode-I and mode-II fracture behavior of fiber-reinforced cemented paste backfill: Effect of curing temperature and curing time

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

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

Quantification of hydration products in cementitious materials incorporating silica nanoparticles

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

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