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Numerical calculation and influencing factors of the volume fraction of interfacial transition zone in concrete

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Science China(Technological Sciences) 2012年第6期55卷 1515-1522页

作者： sun guowen sun Wei ZHANG YunSheng LIU ZhiYong Jiangsu Key Laboratory of Construction Materials Southeast UniversityNanjing 211189China

The determination of volume fraction of interracial transition zone （ITZ） is very important for investigating the quantitative relationship between the microstructure and macroscopical property of concrete. In this paper, based on Lu and Torquato＇s most nearest surface distribution function, a calculating process of volume fraction of ITZ is given in detail according to the actual sieve curve in concrete. Then, quantitative formulas are put forward to measure the influencing factors on the ｜TZ vol- ume fraction. In order to validate the given model, the volume fractions of ITZ obtained by numerical calculation are compared with those by computer simulation. The results show that the two are in good agreement. The order of the factors influencing the ITZ volume fraction is the ITZ thickness, the volume fraction of aggregate and the maximum aggregate diameter for Fuller gradation in turn. The 1TZ volume fraction obtained from the equal volume fraction （EVF） gradation is always larger than that from the Fuller gradation for a given volume fraction of aggregate.

关键词： concrete interfacial transition zone (ITZ) volume fraction Fuller distribution equal volume fraction distribution(EVF) sieve curve

Synthesis and Flocculation of Polyacrylamide with Low Water Absorption for Non-dispersible Underwater Concrete

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Journal of Wuhan University of Technology(Materials Science) 2023年第6期38卷 1404-1413页

作者： LI Hongling YAN Na sun guowen ZHENG Haorui YANG Xinyu Depantment of Chemistry and Miaterials Engineering Xinxiang Normal CollegeXinxiang 453003China School of Materials Science and Engineering Shijiazhuang Tiedao UniversityShijiazhuang 050043China Hebei Key Laboratory of Advanced Materials for Transportation Engineering and Environment Shijiazhuang 050043China

The polyacrylamide which is directly added into concrete shows strong water absorption *** the construction of underwater constructure would demand high amount of water,resulting in poor workability of concrete and strength shrinkage after ***,a kind of anionic polyacrylamide(APAM)grafted with water reducing functional group(-COOH)was synthesized at low temperatures by partial factor design and response surface *** structure and morphology of APAM were characterized by UV,FTIR and SEM *** experimental results show that the molecular weight of the synthesized APAM could reach 11 million,under the condition that the temperature was 35℃,the pH value was 8,the monomer concentration was 27wt%,the initiator dosage was 0.6wt%,and the monomer ratio(n(AM):n(AA))was *** the APAM was applied into the underwater slurry,it presented good flocculation and low water *** the dosage was 1%of the mass of the cement,the water demand increased by 12%,which could meet the self-leveling and anti-dispersity of the underwater slurry at the same *** technology provides technical guidance for the large-scale industrial production of polyacrylamide for underwater concrete construction while achieving environmental protection during production.

关键词： non-dispersible underwater concrete anionic polyacrylamide partial factor design response surfacedesign flocculation

Modeling and Software Development of the Interfacial Transition Zone of Ellipsoidal Aggregate in Cement-Based Composites

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Journal of Wuhan University of Technology(Materials Science) 2019年第3期34卷 648-655页

作者： ZHANG Jianjian sun guowen School of Materials Science and Engineering Shijiazhuang TieDao UniversityShijiazhuang050043China Foundational Subjects Department Shijiazhua TieDao University SiFang CollegeShijiazhuang051132China

The interfacial transition zone (ITZ) between the aggregates and the bulk paste is the weakest zone of ordinary concrete, which largely determines its mechanical and transporting properties. However, a complete understanding and a quantitative modeling of ITZ are still lacking. Consequently, an integrated modeling and experimental study were conducted. First, the theoretical calculation model of the ITZ volume fraction about the rotary ellipsoidal aggregate particles was established based on the nearest surface function formula. Its calculation programs were written based on Visual Basic 6.0 language and achieved visualization and functionalization. Then, the influencing factors of ITZ volume fraction of the ellipsoidal aggregate particles and the overlapping degree between the ITZ were systematically analyzed. Finally, the calculation models of ITZ volume fraction on actual ellipsoidal aggregate were given, based on cobblestones or pebbles particles with naturally ellipsoidal shape. The results indicate that the calculation model proposed is highly reliable.

关键词： interfacial transition zone (ITZ) cement-based composites ellipsoidal aggregate volume fraction visualization software development

Internal Curing Mechanism of Sepiolite in Cement Paste

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Journal of Wuhan University of Technology(Materials Science) 2023年第4期38卷 857-864页

作者：许晨席王彩辉 LI Wenhao sun Kaili ZHANG Guangxing sun guowen KONG Lijuan Hebei Key Laboratory of New Materials for Collaborative Development of Traffic Engineering and Environment Shijiazhuang050043China China State Construction Technical Center Beijing101300China China Railway 18th Bureau Group Co.Ltd Tianjin300222China

In order to explore the internal curing mechanism of sepiolite in cement-based materials,the effects of sepiolite on the water consumption of standard consistency,setting time,viscosity,strength,pore structure characteristics,micro-hardness characteristics and two-dimensional surface characteristics of cement paste were studied,*** experimental results show that the water consumption of standard consistency increases linearly with the increase of sepiolite *** setting time and viscosity are also lengthened and increased with the addition of sepiolite,*** the content of sepiolite exceeds 5%,the strength of the specimen increases *** BET results show that the pore structure of the interfacial transition zone(ITZ)in hardened cement paste(HCP)with sepiolite is optimized after curing for28 d and its pore volume content with below 10 nm is decreased,especially for the specimen with a lower watercement *** characteristics of microhardness and strength of specimens have the same *** electron image(BSE-IA)shows that the ITZ of the specimen with sepiolite is denser and the unhydrated cement particles are less than the reference specimen.

关键词： sepiolite cement paste internal curing

Investigation of the Interfacial Transition Zone between Aggregate-Cement Paste by AC Impedance Spectroscopy

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Journal of Wuhan University of Technology(Materials Science) 2016年第4期31卷 865-871页

作者：孔丽娟 hou lirong wang yuhua sun guowen School of Materials Science and Engineering Shijiazhuang Tiedao University Shijiazhuang 050043 China

Three different types and sizes of coarse aggregate were chosen,and the alternating current（AC） impedance of cement paste samples with and without aggregate was measured at different curing *** on Song’s equivalent circuit model,the electrical properties from the AC impedance results were obtained,and the resistance of connected pores RCCP was used to characterize the microstructure of the interfacial transition zone（ITZ）.The results show that the RCCP of concrete sample with aggregate is lower than that of cement paste sample,which indicates that the introduction of aggregate in cement paste makes the ITZ ***,for the same type of aggregate,an increase in particle size leads to a more porous ITZ,which accounts for the “water effect” and a larger aggregate would accumulate a thicker water film around *** addition,for the same size of aggregate,the physical interaction between aggregate and cement paste is dominant in early age,and the microstructure of the ITZ around limestone aggregate is denser,which mainly depends on its rough surface and high water ***,the microstructures of the ITZ around granite and basalt aggregates are denser in later age,which may be due to their higher chemical activity,and the chemical interaction between them and cement paste resulting in the generation of more *** impedance spectroscopy thus proves to be powerful for evaluation of the microstructure of the ITZ.

关键词： aggregate paste impedance hydration curing Paste limestone sizes characterize porous

Development of a High Early Strength Non-fuorine and Non-alkaline Flash Setting Admixture and Flash Mechanism

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Journal of Wuhan University of Technology(Materials Science) 2024年第6期39卷 1518-1527页

作者： sun guowen YANG Xinyu WANG Fengjuan WANG Jinshuo LIU Zhiyong College of Materials Science and Engineering Shijiazhuang Tiedao UniversityShijiazhuang 050043China College of Materials Science and Engineering Southeast UniversityNanjing 211189China

To solve the problems of high rebound rate and strength reversion of shotcrete,a non-fluorine and non-alkaline liquid flash setting admixture(FSN)with low rebound and high early strength was synthesized under 60-65℃water bath environment through orthogonal test design and taking setting time and compressive strength as *** experimental results show that the optimum mass ratio of FSN is aluminum sulfate:diethanolamine:triethanolamine:pseudo-boehmite:lithium carbonate:water=57%:8%:0.05%:2%:2%:31%.When FSN is added with 7%of the mass of portland cement,the cement paste can be initially set in 3 min and finally set in 5 *** compressive strength of mortar is 1.2 MPa at 6 h,18.0 MPa at 1 d,and more than 100%at 28 days;The microscopic analysis shows that the rapid release of Li^(+),NH^(4+),and CO_(3)^(2-)ions by FSN in the paste solution effectively shortens the induction period of high C_(3)S content in Portland cement,directly forms early coagulation AFt crystals in FSN and CH dominated by Al_(2)(SO_(4))_(3),and forms a large number of C-S-H gels in the later stage,so that the cement can quickly coagulate and harden,and the strength in the later stage is not retracted.

关键词： shotcrete flash setting admixture aluminum sulfate high early strength flash mechanism

Synthesis and Performance Characterization of a Low Adsorption Clay-resistant Polycarboxylate Superplasticizer

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Journal of Wuhan University of Technology(Materials Science) 2021年第3期36卷 446-455页

作者： ZHANG Ying WANG Pengshuo sun guowen YANG Jianming GAO Rui School of Materials Science and Engineering Shijiazhuang Tiedao UniversityShijiazhuang 050043China College of Civil Engineer-ing Yancheng Institute of TechnologyYancheng 224051China State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang050043China Heibei Key Laboratory of Advanced Materials for Transportation Engineering and Environment Shijiazhuang Tiedao UniversityShijiazhuang050043China

A low adsorption clay-resistant polycarboxylate superplasticizer(KN-PC)was synthesized using acrylic acid and isopentenol polyoxyethylene ether as the main reaction *** structural characterization and clay-resistant mechanism of the KN-PC were explored using Fourier transform infrared spectroscopy and X-ray diffraction,and the effect of the KN-PC on the performance of composite paste with various montmorillonite(MMT)contents was *** with ordinary polycarboxylate superplasticizer(PC),the KN-PC has a low sensitivity to the *** the action of the MMT,the adsorption dosage of the KN-PC on the MMT is much smaller than that of the PC.

关键词： polycarboxylate superplasticizer clay-resistant montmorillonite performance synthesis

Theoretical Calculation of ITZ Volume Fraction and Morphological Characterization of Crushed Stone in Concrete

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Journal of Wuhan University of Technology(Materials Science) 2022年第4期37卷 656-665页

作者： ZHANG Jianjian PENG Liang ZHANG Guoqiang sun guowen LIU Zhiyong School of Civil Engineering Harbin Institute of TechnologyHarbin 150090China School of Materials Science and Engineering Shijiazhuang TieDao UniversityShijazhuang 050043China Foundational Subjects Department Shijiazhuang TieDao University SiFang CollegeShijiazhuang 051132China School of Materials Science and Engineering Southeast UniversityNanjing 211189China

According to the morphological characteristics of crushed stone,the sphericity was introduced to establish the theoretical calculation model of volume fraction of interfacial transition zone(ITZ)around crushed *** sphericity of crushed stone was obtained by image processing technology and numerical *** experimental results show that when the maximum particle size of coarse aggregate is less than 31.5 mm,the practical sphericity is generally around 0.75,while the sphericity of sand is generally above *** the closer to 1 the practical sphericity is,the smaller the ITZ volume fraction(V_(ITZ))is,that is,the closer to spherical shape the aggregate is,the lower the ITZ content in concrete *** V_(ITZ) and ITZ thickness in concrete and mortar have a linear relationship,and the ITZ content in concrete is lower than that in mortar at the same aggregate volume fraction.

关键词： crushed stone sphericity interfacial transition zone image processing concrete

Effect of Friction Reclaimed Materials of Waste Brake-shoe on Basic Performance of Mortar

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Journal of Wuhan University of Technology(Materials Science) 2017年第3期32卷 603-610页

作者：王彩辉 HUANG Dongjie FU Hua WU Hongya QIN Guoqiang sun guowen GUO Na School of Materials Science and Engineering Shijiazhuang Tiedao University He Bei Provincial Key Laboratory of Traffic Engineering Materials China Southern Railway (CSR) Group SHIJIAZHUANG Corporation Limited School of Postgraduates

Discarded train brake shoes mainly consist of steel-backed friction material. To be better reutilized, its essential features and its interaction in cement-based material need to be studied. Consequently, particle size analysis, SEM, IR and TGA were used to investigate two types of waste brake shoes, i e, mechanical grinding friction reclaimed material of waste brake-shoe（G-FRMWBS） and pyrolysis-friction reclaimed materials of waste brake-shoe（P-FRMWBS）. The latter exhibited less organic content, larger range of particle size distribution and smaller medium particle diameter. Both types contained inorganic particles of spherical and irregular shapes, striped with steel fiber. Upon isometric substituting fine aggregates, G-FRMWBS lifted the strength of mortar effectively that was increased by 16.6% and 17.5% when the replacing rate was 5%; the value went up to 19.2% and 19.2% when the replacing rate was 10%. Moreover, inclusion of FRMWBS enhanced the chloride penetration resistance, and optimized the pore characteristic and ITZ（interfacial transition zone） as well.

关键词： friction reclaimed materials of waste brake-shoe mortar strength porosity ITZ