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固化反应模型 1

强度增长 1

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Multiscale model of micro curing residual stress evolution in carbon fiber-reinforced thermoset polymer

Xinyu HUI, Yingjie XU, Weihong ZHANG

《机械工程前沿（英文）》 2020年 第15卷 第3期   页码 475-483 doi: 10.1007/s11465-020-0590-6

摘要： In this study, the micro curing residual stresses of carbon fiber-reinforced thermoset polymer (CFRP) composites are evaluated using a multiscale modeling method. A thermochemical coupling model is developed at the macroscale level to obtain the distributions of temperature and degree of cure. Meanwhile, a representative volume element model of the composites is established at the microscale level. By introducing the information from the macroscale perspective, the curing residual stresses are calculated using the microscale model. The evolution of curing residual stresses reveals the interaction mechanism of fiber, matrix, and interphase period during the curing process. Results show that the curing residual stresses mostly present a tensile state in the matrix and a compressive state in the fiber. Furthermore, the curing residual stresses at different locations in the composites are calculated and discussed. Simulation results provide an important guideline for the analysis and design of CFRP composite structures.

关键词： CFRP     curing residual stress     multiscale modeling     finite element method    

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Synthesis of hierarchical nanohybrid CNT@Ni-PS and its applications in enhancing the tribological, curing

Jinian Yang, Yuxuan Xu, Chang Su, Shibin Nie, Zhenyu Li

《化学科学与工程前沿（英文）》 2021年 第15卷 第5期   页码 1281-1295 doi: 10.1007/s11705-020-2007-9

摘要： Poor interfacial adhesion and dispersity severely obstruct the continued development of carbon nanotube (CNT)-reinforced epoxy (EP) for potential applications. Herein, hierarchical CNT nanohybrids using nickel phyllosilicate (Ni-PS) as surface decorations (CNT@Ni-PS) were synthesized, and the nanocomposites derived from varied mass fractions of EP and CNT@Ni-PS were prepared. The morphological structures, tribological performances, curing behaviors and thermal properties of EP/CNT@Ni-PS nanocomposites were carefully investigated. Results show that hierarchical CNT nanohybrids with homogeneous dispersion and well-bonded interfacial adhesion in the matrix are successfully obtained, presenting significantly improved thermal and tribological properties. Moreover, analysis on cure kinetics proves the excellent promotion of CNT@Ni-PS on the non-isothermal curing process, lowering the curing energy barrier steadily.

关键词： nickel phyllosilicate     surface decoration     tribological property     curing kinetics     thermal performance    

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evolutive mode-I and mode-II fracture behavior of fiber-reinforced cemented paste backfill: Effect of curingtemperature 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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The influence of curing conditions on the mechanical properties and leaching of inorganic polymers made

Remus I. Iacobescu, Valérie Cappuyns, Tinne Geens, Lubica Kriskova, Silviana Onisei, Peter T. Jones, Yiannis Pontikes

《化学科学与工程前沿（英文）》 2017年 第11卷 第3期   页码 317-327 doi: 10.1007/s11705-017-1622-6

摘要： This study reports on the impact of the curing conditions on the mechanical properties and leaching of inorganic polymer (IP) mortars made from a water quenched fayalitic slag. Three similar IP mortars were produced by mixing together slag, aggregate and activating solution, and cured in three different environments for 28 d: a) at 20 °C and relative humidity (RH) ~ 50% (T20RH50), b) at 20 °C and RH≥90% (T20RH90) and c) at 60 °C and RH ~ 20% (T60RH20). Compressive strength (EN 196-1) varied between 19 MPa (T20RH50) and 31 MPa (T20RH90). This was found to be attributed to the cracks formed upon curing. Geochemical modelling and two leaching tests were performed, the EA NEN 7375 tank test, and the BS EN 12457-1 single batch test. Results show that Cu, Ni, Pb, Zn and As leaching occurred even at high pH, which varied between 10 and 11 in the tank test’s leachates and between 12 and 12.5 in the single batch’s leachates. Leaching values obtained were below the requirements for non-shaped materials of Flemish legislation for As, Cu and Ni in the single batch test.

关键词： inorganic polymer     geochemical leaching modelling     heavy metals     recycling     non-ferrous fayalitic slag     curing    

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Synthesis of hierarchical nanohybrid CNT@Ni-PS and its applications in enhancing the tribological, curing

《化学科学与工程前沿（英文）》 2022年 第16卷 第10期   页码 1530-1530 doi: 10.1007/s11705-022-2240-5

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Influence of initial curing conditions and exposure environments on chloride migration in concrete using

Wen XUE, Weiliang JIN, Hiroshi YOKOTA,

《结构与土木工程前沿（英文）》 2010年 第4卷 第3期   页码 348-353 doi: 10.1007/s11709-010-0077-3

摘要： To investigate the influence of initial curing conditions and exposure environments on chloride ions’ migration in concrete, the specimens that were cured in different conditions and placed in several marine environments were studied. The amount of chloride ions passing through the specimen’s section was monitored in the accelerated chloride migration test. The effective chloride diffusion coefficients () were calculated from the steady-state on the basis of Nernst-Planck’s equation. The results indicated that the initial curing conditions and the wet-dry interval of external environments have coupling influence on effective diffusion coefficient of chloride ion significantly. reflected the density and pore connectivity of concrete. The co-effects of the initial curing condition and following exposure environment should be taken into account in durability design for concrete structure located in marine environment.

关键词： durability     effective diffusion coefficient     steady-state     migration test    

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国产环氧沥青混合料固化强度增长规律研究

钱振东,王亚奇,沈家林

《中国工程科学》 2012年 第14卷 第5期   页码 90-95

摘要：

研究了环氧沥青混合料的强度形成机理，在此基础上对影响环氧沥青混合料强度的两个重要因素即混合料的容留时间、养生温度进行了研究，确定了不同温度下环氧沥青混合料的容留时间范围及强度增长规律；采用差示扫描量热法（DSC）测得环氧沥青结合料在不同升温速率下的动态DSC曲线，通过非线性回归求得固化动力学关键参数，建立环氧沥青结合料的固化反应模型。研究结果可以指导环氧沥青混合料的生产与施工，同时对铺装层开放交通时间的确定有参考意义。

关键词： 环氧沥青     强度增长     时温条件     固化反应模型    

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Influence of accelerated curing on the compressive strength of polymer-modified concrete

Izhar AHMAD; Kashif Ali KHAN; Tahir AHMAD; Muhammad ALAM; Muhammad Tariq BASHIR

《结构与土木工程前沿（英文）》 2022年 第16卷 第5期   页码 589-599 doi: 10.1007/s11709-022-0789-1

摘要： In recent building practice, rapid construction is one of the principal requisites. Furthermore, in designing concrete structures, compressive strength is the most significant of all parameters. While 3-d and 7-d compressive strength reflects the strengths at early phases, the ultimate strength is paramount. An effort has been made in this study to develop mathematical models for predicting compressive strength of concrete incorporating ethylene vinyl acetate (EVA) at the later phases. Kolmogorov-Smirnov (KS) goodness-of-fit test was used to examine distribution of the data. The compressive strength of EVA-modified concrete was studied by incorporating various concentrations of EVA as an admixture and by testing at ages of 28, 56, 90, 120, 210, and 365 d. An accelerated compressive strength at 3.5 hours was considered as a reference strength on the basis of which all the specified strengths were predicted by means of linear regression fit. Based on the results of KS goodness-of-fit test, it was concluded that KS test statistics value (D) in each case was lower than the critical value 0.521 for a significance level of 0.05, which demonstrated that the data was normally distributed. Based on the results of compressive strength test, it was concluded that the strength of EVA-modified specimens increased at all ages and the optimum dosage of EVA was achieved at 16% concentration. Furthermore, it was concluded that predicted compressive strength values lies within a 6% difference from the actual strength values for all the mixes, which indicates the practicability of the regression equations. This research work may help in understanding the role of EVA as a viable material in polymer-based cement composites.

关键词： compressive strength prediction     polymer-modified concrete     linear regression fit     early age strength     ethylene vinyl acetate    

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Assessing compressive strengths of mortar and concrete from digital images by machine learning techniques

Amit SHIULY; Debabrata DUTTA; Achintya MONDAL

《结构与土木工程前沿（英文）》 2022年 第16卷 第3期   页码 347-358 doi: 10.1007/s11709-022-0819-z

摘要： Compressive strength is the most important metric of concrete quality. Various nondestructive and semi-destructive tests can be used to evaluate the compressive strength of concrete. In the present study, a new image-based machine learning method is used to predict concrete compressive strength, including evaluation of six different models. These include support-vector machine model and various deep convolutional neural network models, namely AlexNet, GoogleNet, VGG19, ResNet, and Inception-ResNet-V2. In the present investigation, cement mortar samples were prepared using each of the cement:sand ratios of 1:3, 1:4, and 1:5, and using the water:cement ratios of 0.35 and 0.55. Cement concrete was prepared using the cement:sand:coarse aggregate ratios of 1:5:10, 1:3:6, 1:2:4, 1:1.5:3 and 1:1:2, using the water:cement ratio of 0.5 for all samples. The samples were cut, and several images of the cut surfaces were captured at various zoom levels using a digital microscope. All samples were then tested destructively for compressive strength. The images and corresponding compressive strength were then used to train machine learning models to allow them to predict compressive strength based upon the image data. The Inception-ResNet-V2 models exhibited the best predictions of compressive strength among the models tested. Overall, the present findings validated the use of machine learning models as an efficient means of estimating cement mortar and concrete compressive strengths based on digital microscopic images, as an alternative nondestructive/semi-destructive test method that could be applied at relatively less expense.

关键词： support vector machine     deep convolutional neural network     microscope     digital image     curing period    

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Accelerated engineering properties of high and low volume fly ash concretes reinforced with glued steel fibers

Vallarasu Manoharan SOUNTHARARAJAN, Dr. Anandan SIVAKUMAR

《结构与土木工程前沿（英文）》 2013年 第7卷 第4期   页码 429-445 doi: 10.1007/s11709-013-0226-6

摘要： The present study focuses on the improvement of pozzolanic reaction of fly ash particles with the cement hydration products. Low and high volume fly ash concrete mixtures were studied systematically with the addition of accelerating admixtures and accelerated curing of the concrete specimens in a steam chamber for 18 h at 75°C. Also, the reinforcing effects of glued steel fibers addition on the compressive and flexural performance of fly ash concrete were investigated. The test results indicated that the addition of accelerator improved the rate of hardening and the inclusion of steel fibers provided higher flexural performance. Also, it can be noted that the high volume fly ash (50%) addition in concrete showed a reduction in strength; however, the addition of accelerator has compensated the deceleration in strength gain. The proper selection of concrete ingredients, addition of accelerator and initial steam curing for 18 h showed better improvement on the engineering properties in fly ash concrete. A maximum increase (41.7%) in compressive strength of fly ash concrete around 52.90 MPa was noticed for 25% fly ash substitution and 1.5% steel fibers addition. Dynamic elastic modulus was also calculated in loaded concrete specimen using ultrasonic pulse velocity test and showed a good agreement with the experimental value.

关键词： fly ash     pozzolanic index     steam curing     superplasticizer     accelerator     steel fibres     elastic modulus    

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Improved “cure on demand” of aromatic bismaleimide with thiol triggered by retro-Diels-Alder reaction

Vincent Froidevaux, Mélanie Decostanzi, Abdelatif Manseri, Sylvain Caillol, Bernard Boutevin, Rémi Auvergne

《化学科学与工程前沿（英文）》 2021年 第15卷 第2期   页码 330-339 doi: 10.1007/s11705-020-1929-6

摘要： This study focuses on the synthesis of new liquid aromatic bismaleimide monomers in order to improve self-curing on demand (SCOD) systems previously based on aliphatic bismaleimides. These SCOD systems are based on Diels-Alder (DA)/retro-DA reactions. The syntheses of new different aromatic bismaleimides with ester and amide bonds are presented. These maleimides have been protected using DA reaction and characterized by H NMR analysis to determine protection rate and diastereomer ratios. The retro-DA reactions of both aromatic and aliphatic DA adducts in presence of thiol molecules were studied. Kinetic analysis was monitored by H NMR and compared to model study. Finally, both aromatic and aliphatic bismaleimides-based polymers were synthesized with 2-mercaptoethyl ether and thermal properties of polymers were compared. The glass transition temperature values ranged from –20 °C to 14 °C and very good thermal stabilities were observed (up to 300 °C).

关键词： thiol-ene polymerization     self-curing on demand     thia-michael addition     Diels-Alder     maleimide    

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标题 作者 时间 类型 操作

Multiscale model of micro curing residual stress evolution in carbon fiber-reinforced thermoset polymer

Xinyu HUI, Yingjie XU, Weihong ZHANG

期刊论文

Synthesis of hierarchical nanohybrid CNT@Ni-PS and its applications in enhancing the tribological, curing

Jinian Yang, Yuxuan Xu, Chang Su, Shibin Nie, Zhenyu Li

期刊论文

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

期刊论文

The influence of curing conditions on the mechanical properties and leaching of inorganic polymers made

Remus I. Iacobescu, Valérie Cappuyns, Tinne Geens, Lubica Kriskova, Silviana Onisei, Peter T. Jones, Yiannis Pontikes

期刊论文

Synthesis of hierarchical nanohybrid CNT@Ni-PS and its applications in enhancing the tribological, curing

期刊论文

Influence of initial curing conditions and exposure environments on chloride migration in concrete using

Wen XUE, Weiliang JIN, Hiroshi YOKOTA,

期刊论文

国产环氧沥青混合料固化强度增长规律研究

钱振东,王亚奇,沈家林

期刊论文

Influence of accelerated curing on the compressive strength of polymer-modified concrete

Izhar AHMAD; Kashif Ali KHAN; Tahir AHMAD; Muhammad ALAM; Muhammad Tariq BASHIR

期刊论文

Assessing compressive strengths of mortar and concrete from digital images by machine learning techniques

Amit SHIULY; Debabrata DUTTA; Achintya MONDAL

期刊论文

Accelerated engineering properties of high and low volume fly ash concretes reinforced with glued steel fibers

Vallarasu Manoharan SOUNTHARARAJAN, Dr. Anandan SIVAKUMAR

期刊论文

Improved “cure on demand” of aromatic bismaleimide with thiol triggered by retro-Diels-Alder reaction

Vincent Froidevaux, Mélanie Decostanzi, Abdelatif Manseri, Sylvain Caillol, Bernard Boutevin, Rémi Auvergne

期刊论文