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Journal of Wuhan University of Technology(Materials Science) 2024年第5期39卷 1169-1176页

作者： XIONG Xuan HE Yongjia LÜLinnü MA Jie WANG Fazhou State Key Laboratory of Silicate Materials for Architectures Wuhan University of TechnologyWuhan 430070China School of Materials Science and Engineering Wuhan University of TechnologyWuhan 430070China Hubei Key Laboratory of Theory and Application of Advanced Materials Mechanics School of ScienceWuhan University of TechnologyWuhan 430070China China Railway Design Corporation Tianjin 300250China

A ternary system comprising Ca_(20)Al_(26)Mg_(3)Si_(3)O_(68)(Q-phase),limestone,and metakaolin is proposed,and its hydration behavior,hydration product phases,microstructure,and mechanical properties are investigated and compared with pure Q-phase *** results indicate that the ternary system exhibits exceptional and sustained compressive strength even under a 40℃environment,significantly outperforming pure *** mechanism lies in that metakaolin effectively inhibits the transformation of metastable ***,the interactions among Q-phase,limestone,and metakaolin further enhance the cementitious *** ternary system effectively addresses potential issues of strength loss in Q-phase cement application,and as a low-carbon cementitious material system,it holds promising potential applications.

关键词： Q-phase limestone metakaolin hydration compressive strength

Replacement of alkali silicate solution with silica fume in metakaolin-based geopolymers

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International Journal of Minerals,Metallurgy and Materials 2019年第5期26卷 555-564页

作者： Ahmed Nmiri Myriam Duc Noureddine Hamdi Oumaya Yazoghli-Marzouk Ezzeddine Srasra National Center for Research in Materials Sciences Technop?le Borj Cedria (CNRSM) Department of Chemistry Faculty of Sciences of Tunis University of Tunis El-Manar French Institute of Science and Technology for Transport Development and Networks (IFSTTAR) Center for Studies and Expertise on Risks Environment Mobility and Development (CEREMA)

A metakaolin(Mk)-based geopolymer cement from Tunisian Mk mixed with different amounts of silica fume(SiO_2/Al_2O_3 molar ratio varying between 3.61 and 4.09) and sodium hydroxide(10M) and without any alkali silicate solution, is developed in this work. After the samples were cured at room temperature under air for 28 d, they were analyzed by X-ray diffraction(XRD), Fourier transform infrared(FTIR) spectroscopy, environmental scanning electron microscopy, mercury intrusion porosimetry, ^(27)Al and ^(29)Si nuclear magnetic resonance(NMR) spectroscopy, and compression testing to establish the relationship between microstructure and compressive strength. The XRD, FTIR, and ^(27)Al and ^(29)Si NMR analyses showed that the use of silica fume instead of alkali silicate solutions was feasible for manufacturing geopolymer cement. The Mk-based geopolymer with a silica fume content of 6 wt%(compared with those with 2% and 10%), corresponding to an SiO_2/Al_2O_3 molar ratio of 3.84, resulted in the highest compressive strength, which was explained on the basis of its high compactness with the smallest porosity. Silica fume improved the compressive strength by filling interstitial voids of the microstructure because of its fine particle size. In addition, an increase in the SiO_2/Al_2O_3 molar ratio, which is controlled by the addition of silica fume, to 4.09 led to a geopolymer with low compressive strength, accompanied by microstructures with high porosity. This high porosity, which is responsible for weaknesses in the specimen, is related to the amount of unreacted silica fume.

关键词： metakaolin silica fume geopolymer cement compressive strength

CO_(2)and Cost-Based Optimum Design of Sustainable metakaolin-Modified Concrete

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Journal of Renewable Materials 2022年第9期10卷 2431-2450页

作者： Xiaoyong Wang Department of Architectural Engineering Department of Integrated Energy and Infra SystemKangwon National UniversityChuncheon-si24341Korea

metakaolin is a highly reactive pozzolanic material that is widely utilized for enhancing the performance of *** study offers a framework for the mixture design of sustainable metakaolin-modified concrete with low CO_(2)emissions and low *** design strengths after 28 days are first formulated,with values such as 30,40,50,and 60 MPa.A genetic algorithm is then used to determine the optimal *** CO_(2)and cost are set as the aims of the genetic *** strength of the concrete,its workability(slump),and carbonation service life with climate change are set as constraints of the genetic *** design cases are considered:1)low-CO_(2)concrete with no carbonation,2)low-CO_(2)concrete with carbonation,3)low-material cost concrete with carbonation,4)low-total cost concrete with carbonation,and 5)low-total cost concrete with climate *** on the analysis,the following results are found:1)When the design’s strength is 30 MPa,to satisfy the requirement of carbonation durability,the concrete real strength should exceed 30 ***,after considering climate change,the concrete real strength should be further improved.2)When the design strength is 40,50,or 60 MPa for low-total-cost concrete,climate change has no impact on the optimal design because the concrete has sufficient carbonation resistance.3)Low-material-cost concrete has the same mixture as low-total-cost concrete because compared with the material cost,the CO_(2)emission cost is much ***,for low-material-cost or low-total-cost concrete,the metakaolin content is at the lower limit because the price of metakaolin is much higher than that of ***,the proposed model covered different aspects of sustainable concrete,such as cost and CO_(2)emissions,clarified various decisive factors of mix design,such as strength and carbon durability,and considered different conditions of climate change,such as no climate change and Representative Concentra

关键词： metakaolin CO_(2) cost optimal design carbonation climate change

Influences of Multi-Component Supplementary Cementitious Materials on the Performance of metakaolin Based Geopolymer

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Journal of Renewable Materials 2022年第7期10卷 1813-1828页

作者： Wu Jing Ren Luo Sha Ding Ping Duan School of Civil Engineering and Architecture Wuhan University of TechnologyWuhan430070China Wuhan Hanyang Municipal Construction Group Co. Ltd.Wuhan430050China Faculty of Materials Science and Chemistry Key Laboratory of Geological Survey and Evaluation of Ministry of EducationChina University of GeosciencesWuhan430074China Guangxi Key Laboratory of New Energy and Building Energy Saving Guilin University of TechnologyGuilin541004China Zhejiang Institute China University of Geosciences(Wuhan)Hangzhou311305China Key Laboratory of Advanced Building Materials of Anhui Province Anhui Jianzhu UniversityHefei230022China Key Laboratory of Road Structure and Materials of Ministry of Transport Chang’an UniversityXi’an710064China

In this study,the workability and reaction mechanism of metakaolin(MK)based geopolymer blended with rice husk ash(RHA)and silica fume(SF)was *** prepared samples were subjected to tests including compressive strength and fluidity tests.X-ray diffraction(XRD)and Scanning electron microscope(SEM)were employed to explore the phase composition and microstructure of *** molecular bonding information of geopolymer was provided by Fourier transform infrared spectroscopy(FTIR).Meanwhile,the porosity of geopolymer was obtained by Mercury intrusion porosimeter(MIP)*** high-activity RHA obtained after calcination at 600℃ was used as a supplementary cementitious material to prepare *** properties of preventing morphology cracking and compressive strength are *** addition of RHA and SF changes the working performance of MK based geopolymer and provided a theoretical basis for future practical ***,the high chemical activity of SF and RHA contributes to the healing of microcracks.

关键词： Rice husk ash silica fume metakaolin geopolymer

Nanoindentation Characteristics of Calcium Hydroxide-metakaolin Blended with Sodium Hydroxide Solutions

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Journal of Wuhan University of Technology(Materials Science) 2014年第1期29卷 185-189页

作者：何智海钱春香 ZHANG Yi ZHAO Fei College of Materials Science and Engineering Southeast University Jiangsu Key Lab of Construction Materials

In order to determine the active mechanism of metakaolin(MK) as partial replacement of cement in concrete from the nanoscale structure perspective, nanoindentation characteristics of calcium hydroxide(CH)-MK blended with 5 M sodium hydroxide(NaOH) solutions simulating the condition of MK in concrete has been studied. The results indicate that three distinct phases are found by the nanoindentation and BSE tests, such as HD C-S-H gel, LD C-S-H gel and the reaction products with the network structure, the residual unreacted MK and CH, respectively. The volume fraction of HD C-S-H gel is about 96% of all reaction product phases. This means that the use of MK in concrete can increase the volume fraction of HD C-S-H gel and thus will improve the properties of concrete.

关键词： nanoindentation metakaolin calcium hydroxide C-S-H gel elastic modulus

Pore Size Distribution of High Performance metakaolin Concrete

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Journal of Wuhan University of Technology(Materials Science) 2002年第1期17卷 42-46页

作者： C.S.Poon S.C.Kou L.Lam Department of Civil and Structural Engineering The Hong Kong Polytechnic University Hong Kong China

The Compressive strength, porosity and pore size distribution of high performance metakaolin (MK) concrete were investigated. Concretes containing 0,5% , 10% and 20% metakaolin were prepared at a water / cementitious material ratio ( W/C) of 0. 30. In parallel, concrete mixtures with the replacement of cement by 20% fly ash or 5 and 10% silica fume were prepared for comparison. The specimens were cured in water at 27℃ for 3 to 90 days. The results show that at the early age of curing (3 days and 7 days), metakaolin replacements increase the compressive strength, but silica fume replacement slightly reduces the compressive strength. At the age of and after 28 days , the compressive strength of the concrete with metakaolin and silica fume replacement increases. A strong reduction in the total porosity and average pore diameter were observed in the concrete with MK 20% and 10% in the first 7 days.

关键词： high performance concrete metakaolin pore size distribution

In-situ Synthesis of ZSM-5 Zeolite from metakaolin/Spinel and Its Catalytic Performance on Methanol Conversion

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China Petroleum Processing & Petrochemical Technology 2010年第1期12卷 23-28页

作者： Liu Ye Yu Xianbo Qin Lei Wang Jingdai Yang Yongrong (Department of Chemical and Biochemical Engineering,Zhejiang University,Hangzhou 310027) Department of Chemical and Biochemical Engineering Zhejiang University Hangzhou 310027 China

ZSM-5 zeolite was in-situ synthesized from metakaolin or s alumina sources, respectively. The ZSM-5 zeolite was characterized pinel by incorporating additional silica and by X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, Fourier transform infrared （FT-IR） spectroscopy and N2 adsorption measurement. This supported zeolite was tested on the methanol to propylene （MTP） processes. Experimental results showed that the ZSM-5 zeolite exhibited high selectivity for propylene. The yield of propylene on ZSM-5 zeolite made from metakaolin was increased by 17.73%, while that on ZSM-5 zeolite made from spinel was raised by 9.90%, compared to that achieved with the commercial ZSM-5 zeolite. The significant increase in propylene production is probably due to the distinctive morphology of the ZSM-5 zeolite, which possessed a rough external surface covered with sphere-like particles and distribution of small crystals sized at around 400--500 nm. This morphology could help to generate more crystal defects so that more active centers could be exposed to the reaction mixture. In addition, the zeolite product had a gradient pore distribution and many medium Brǒnsted acid sites, both of which might also contribute to the increased propylene production.

关键词： metakaolin spinel in-situ synthesis of ZSM-5 methanol to propylene (MTP)

Properties of High Volume Fly Ash Concrete Compensated by metakaolin or Silica Fume

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Journal of Wuhan University of Technology(Materials Science) 2007年第4期22卷 728-732页

作者：魏小胜 Department of Civil Engineering Huazhong University of Science and Technology

The compressive strength and dynamic modulus of high volume fly ash concrete with incorporation of either metakaolin or silica fume were investigated. The water to cementitious materials ratio was kept at 0.4 for all mixtures. The use of high volume fly ash in concrete greatly reduces the strength and dynamic modulus during the first 28 days. The decreased properties during the short term of high volume fly ash concrete is effectively compensated by the incorporation of metakaolin or silica fume. The DTA results confirmed that metakaolin or silica fume increase the amount of the hydration products. An empirical relationship between dynamic modulus and compressive strength of concrete has been obtained. This relation provides a nondestructive evaluation for estimating the strength of concrete by use of the dynamic modulus.

关键词： high volume fly ash metakaolin silica fume dynamic modulus

Performance Improved of a Lime and Hemp-Based Concrete through the Addition of metakaolin

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Fluid Dynamics & Materials Processing 2023年第5期19卷 1091-1113页

作者： Suzanne Daher Amar Benazzouk Haïkel Ben Hamed Thierry Langlet Universitéde Picardie Jules Verne Avenue des Facultés Amiens80025France

This work describes in detail the experimental investigation of the physico-mechanical properties of nonstructural hemp concrete(usually used as insulating wall material)when the Air-lime based Tradial PF70 binder is partially replaced using *** objective is to reduce the amount of free Ca2+ions in the binder as these are responsible for the degradation of vegetables particles and can therefore induce a loss of mechanical *** order to assess the effectiveness of pozzolanic reaction,amounts of 0%,10%,and 20%*** Air-lime binder were replaced by the metakaolin material,while testing the mechanical properties of concrete specimens containing 200%and 300%of hemp *** SEM and EDX analysis,a tight relationship has been found to exist between the metakaolin content and physical-mechanical properties of *** pozzolanic reaction consumes calcium hydroxide from binder to produce Hydrated Calcium Silicates(C-S-H)and in turn,this leads to a decrease in the pH-value of the pore solution which is the main factor responsible for hemp particle degradation.

关键词： Agro-sourced materials hemp particles tradical PF70 binder metakaolin pozzolanic products mechanical properties deformability particle mineralisation SEM and EDX analyses

Preparation and Microstructure Analysis of High Strength Cementitious Materials Containing metakaolin

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武汉理工大学学报 2010年第17期32卷 117-122,136页

作者： YU R SHUI Z H DONG J School of Materials Science and Engineering Wuhan University of TechnologyWuhan 430070China

The preparation and microstructure analysis of high strength cementitious materials containing metakaolin (MK) was studied in this paper. The MK was prepared firstly,and then was mixed with fly ash,ground blast furnace slag,quartz powder and cement with different percentage to produce high strength cementitious materials. After cured under different environment,the compressive strength of such materials was tested. Techniques of X-ray diffraction (XRD) and scanning electron microscopy (SEM) were further employed to identify the composition and microstructure. The results obtained reveal that the compressive strength of such materials mainly effected by component of raw materials,the water binder ratio (W/B) and the curing regime. When the three factors above are optimized,the compressive strength of such materials can get to 156 MPa in maximum. The X-ray diffraction analysis and the scanning electron microscopic images indicated that under optimal curing condition,more raw materials can take chemical reaction and the microstructure is dense to yield good mechanical properties.

关键词： preparation microstructure analysis high strength cementitious materials metakaolin