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Effect of Glutinous Rice Flour on Mechanical Properties and Microstructure of cement-based materials

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Journal of Wuhan University of Technology(materials Science) 2023年第2期38卷 394-400页

作者： FENG Qi LU Bao WANG Dan Guangxi Key Lab of Road Structure and materials Guangxi Transportation Science and Technology Group Co.LtdNanning5300007China Key Laboratory for Advanced Technology in Environment Protection of Jiangsu Province Yancheng Institute of TechnologyYancheng224051China Special Glass Key Lab of Hainan Province&State Key Laboratory of Marine Resource Utilization in South China Sea Hainan UniversityHaikou570228China

The mechanism of glutinous rice flour,a kind of natural admixture,on the hydration process,setting time,and microstructure of the Portland cement was *** experimental results show that the glutinous rice flour has an obvious setting retarding effect on cement *** optimal dosage of the glutinous rice flour is 3wt%.In this case,the initial and final setting time of the paste are delayed by 140 and185 min,*** flexural and compressive strengths of the hardened paste are increased by 0.35%and 0.07%after 56 d of *** glutinous rice flour hinders the mineral dissolution process and decreases the concentration of calcium ion at the initial stage of hydration due to the complexation effect,thereby hindering the nucleation and growth of CH and C-S-H phases and prolonging the hydration ***,C-S-H phases combine with the glutinous rice flour to contribute the bonding effect together,which compacts the microstructure of hardened cement pastes at the later hydration stage of cement ***,in-depth investigation on the utilization of glutinous rice flour as the admixture for the Portland cement is expected to be meaningful for the control of hydration exothermic rate and setting time.

关键词： glutinous rice flour cement-based materials mechanical properties setting time

Autogenous healing mechanism of cement-based materials

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结构与土木工程前沿:英文版 2023年第6期17卷 948-963页

作者： Desheng LI Hao ZHENG Kang GU Lei LANG Shang SHI Bing CHEN Department of Civil Engineering School of ScienceNanjing University of Science and TechnologyNanjing210094China School of Transportation Science and Engineering Harbin Institute of TechnologyHarbin150090China State Key Laboratory of Ocean Engineering Shanghai Jiao Tong UniversityShanghai200240China State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil MechanicsWuhan430071China

Autogenous self-healing is the innate and fundamental repair capability of cement-based materials for healing *** researchers have investigated factors that influence autogenous ***,systematic research on the autogenous healing mechanism of cement-based materials is *** healing process mainly involves a chemical process,including further hydration of unhydrated cement and carbonation of calcium oxide and calcium ***,the autogenous healing process is influenced by the material constituents of the cement composite and the ambient *** this study,different factors influencing the healing process of cement-based materials were *** electron microscopy and optical microscopy were used to examine the autogenous healing mechanism,and the maximum healing capacity was ***,detailed theoretical analysis and quantitative detection of autogenous healing were *** 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

M-T Scheme for Predicting Effective Diffusion Coefficient of Chloride Ions in cement-based materials

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Journal of Wuhan University of Technology(materials Science) 2020年第3期35卷 520-527页

作者： SUN Guowen ZHANG Jianjian ZHANG Lijuan CAO Tongning WANG Penshuo ZHANG Ying YAN Na State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShiji-azhuang 050043China School of materials Science and Engineering Shijiazhuang TieDao UniversityShijiazhuang 050043China Foundational Subjects Department Shijiazhuang TieDao University SiFang CollegeShijiazhuang 051132China

To investigate the transport characteristics of chloride ions in cement-based materials, the Mori-Tanaka (M-T) prediction scheme of the effective diffusion coefficient in composites containing single-phase and multi-phase inclusions is systematically deduced based on the theory of composite mechanics and porous medium. The volume fraction, morphology and distribution of aggregates, as well as the interfacial transition zone (ITZ) are fully taken into consideration in this proposed model. The results show that the algorithm of M-T prediction scheme with high accuracy is relatively simple.

关键词： M-T scheme chloride ion effective diffusion coefficient cement-based materials ITZ

Hydration Process of cement-based materials by AC Impedance Method

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Journal of Wuhan University of Technology(materials Science) 2015年第1期30卷 142-146页

作者：随春娥李悦 DING Qingjun Trasportation Institute Inner Mongolia University School of Civil Engineering Beijing University of Technology School of materials Science and Engineering Wuhan University of Technology

AC impedance is a new method to study the changes of pore structure and the hydration degree during the hydration and hardening process of cement paste by the change of the electrochemical parameters. Employing AC impedance method, we studied the hydration and hardening process of cement paste with fly ash and slag, and analyzed the influence of different hydration age, water-binder ratio and mineral admixture on the impedance parameters. Moreover, we compared the results with those by the conventional porosity testing method and X-ray diffraction method. The results showed that AC impedance could be taken as a new technology in cement and concrete research.

关键词： cement-based materials mineral admixture hydration process AC impedance

Effects of Specimen Shape and Size on Water Loss and Drying Shrinkage of cement-based materials

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Journal of Wuhan University of Technology(materials Science) 2013年第4期28卷 733-740页

作者：巴明芳钱春香 WANG Hui Faculty of Architectural Civil Engineering and Environment Ningbo University School of materials Science and Engineering Southeast University

The effects of specimen size and shape on development of water loss and shrinkage of mortar and concrete respectively were investigated. The experimental results showed that the effects of specimen size and shape on water loss ratio were consistent with those on drying shrinkage strain. It is also indicated that drying shrinkage strain has obvious linear correlation with water loss ratios independent of specimen size and shape. The effects of specimen size and shape on the water loss ratio were embodied in established model of averaged relative humidity improved by considering effects of sequential hydration and calculated by finite difference method. Furthermore, the effects of specimen size and shape on drying shrinkage strain of concrete were experimentally deduced and applied to modify criterion EB-FIP1990. The comparison between experimental and calculated results shows that the modified EB-FIP1990 can be adopted to predict drying shrinkage strain of concrete with reasonable accuracy.

关键词： cement-based materials drying shrinkage water loss effective drying thickness

Salt freezing resistance improvement of cement-based materials incorporated with calcined layered double hydroxide

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Journal of Traffic and Transportation Engineering(English Edition) 2023年第3期10卷 427-440页

作者： Jinyang Huo Tonghuan Zhang Zhenjun Wang Xiaofeng Wang Xin Ji Pei Wang School of materials Science and Engineering Chang'an UniversityXi'an 710064China Engineering Research Center of Transportation materials of Ministry of Education Chang'an UniversityXi'an 710064China Henan Communications Planning&Design Institute Co. Ltd.Zhengzhou 450052China

Salt freezing damage has severe impacts on durability of cement-based materials(CBMs).Calcined layered double hydroxide(CLDH),as an efficient environmental-friendly adsorption material,can impart excellent salt freezing resistance to *** this work,salt freezing resistance improvement of CBMs incorporated with CLDH was experimentally evaluated by chloride binding capacity,mass loss rate,relative dynamic elastic modulus,setting time,compressive strength,and micro structure *** these,the salt freezing damage model was established to effectively express the quantitative relationship between influencing factors and evaluation indexes of the salt freezing resistance of *** show that CLDH can reconstruct its original layered structure to form reconstructed layered double hydroxide(RLDH).RLDH combines with chloride ions to form RLDH-Cl recrystallization,which can improve chloride binding capacity and pore structures of CBMs to relieve the salt freezing *** salt freezing damage model indicates that the suitable CLDH content can evidently alleviate the salt freezing damage,which facilitates the quantitative analysis of the effect of CLDH on the salt freezing resistance of CBMs.

关键词： cement-based materials Calcined layered double hydroxide Salt freezing resistance Micro structure Salt freezing damage

Three-dimensional analysis of micro defect morphologies in cement-based materials using focused ion beam tomography

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Science China(Technological Sciences) 2012年第6期55卷 1539-1544页

作者： WAN KeShu SUN Wei TANG ChunKai RONG ZhiDan Jiangsu Key Laboratory of Construction materials Nanjing 211189China School of materials Science and Engineering Southeast UniversityNanjing 211189China

Although there has been much research of cracks of the cement-based materials using optical and electron microscopy two-dimensional (2D) imaging methods, the real three-dimensional (3D) crack shapes have not previously been revealed. Thanks to the focused ion beam (FIB) tomography and the follow-up image processing, two 3D subsurface cracks and a cluster of inner cracks were picked out and discussed in this research. It was found that the subsurface crack (its length is about 15 part, width about 1-5 prn, and opening about 1 ~tm) was much larger than the inner crack (its length and width are about 1-5 pro, opening is from 200 nm to 1 pan), which arose from the sample preparation process. Besides, it was revealed that most of the inner cracks were in the form of clusters.

关键词： focused ion beam (FIB) microstructure crack cement-based materials tomography

Self-healing Action of Permeable Crystalline Coating on Pores and Cracks in cement-based materials

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Journal of Wuhan University of Technology(materials Science) 2005年第1期20卷 89-91,97页

作者：王桂明余剑英 School of materials Science and Engineering Wuhan University of Technology Wuhan 430070China

The self-healing action of a permeable crystalline coating on the po rous mortar was investigated by two times impermeability test. Moreover, the sel f-healing mechanism of cement-based materials with the permeable crystalline c oating was studied by SEM. The results indicate that the permeable crystalline c oating not only seals the pores and cracks in mortar during its curing process, but also heals the permeable pathway caused by first impermeability test or crac ks produced by freeze-thaw cycles. Therefore, cement-based materials can be im proved by the permeable crystalline coating for the self-healing function. SEM images prove that the self-healing function is realized by generating a great q uantity of non-soluble dendritic crystalline within the pores and cracks, which prevents the penetration of water and other liquids.

关键词： cement-based materials self-healing impermeability crystalline

Elastoplastic cup model for cement-based materials

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Water Science and Engineering 2010年第1期3卷 102-112页

作者： Yan ZHANG Jian-fu SHAO College of Mechanics and materials Hohai University Nanjing 210098 P. R. China Laboratory of Mechanics of Lille UMR 8107 CNRS Villeneuve d＇Ascq 59655 France

based on experimental data obtained from triaxial tests and a hydrostatic test, a cup model was formulated. Two plastic mechanisms, respectively a deviatoric shearing and a pore collapse, are taken into account. This model also considers the influence of confining pressure. In this paper, the calibration of the model is detailed and numerical simulations of the main mechanical behavior of cement paste over a large range of stress are described, showing good agreement with experimental results. The ease study shows that this cup model has extensive applicability for cement-based materials and other quasi-brittle and high-porosity materials in a complex stress state.

关键词： cup model cement-based materials plastic shearing mechanism plastic porecollapse mechanism numerical simulation