Summary

在界面过渡区(ITZ)的聚合曲面形态测定

Published: December 16, 2019
doi:

Summary

本文提出了一种说明集面形态学对ITZ微观结构的影响的协议。通过数字图像处理对SEM-BSE图像进行了定量分析,获得了ITZ的孔隙度梯度,并进一步采用了K-均值聚类算法,建立了孔隙梯度与表面粗糙度的关系。

Abstract

本文提出了一种综合方法,说明围绕聚合的界面过渡区(ITZ)分布不均,以及聚合表面形态对性指标的形成的影响。首先,用球形陶瓷颗粒在水泥基质的中央部分制备一个模型混凝土样品,作为普通混凝土/砂浆中使用的粗骨。固化至设计年龄后,通过X射线计算机断层扫描样品,以确定陶瓷颗粒在水泥基质中的相对位置。选择三个位置:在聚合上方、聚合侧和聚合下方。经过一系列处理后,使用 SEM-BSE 检测器扫描样品。利用数字图像处理方法(DIP)对结果图像进行进一步处理,以获得ITZ的定量特性。基于数字图像的像素层次,对表面形态进行了特征化。此后,采用K-值聚类法来说明表面粗糙度对ITZ形成的影响。

Introduction

在中观尺度上,水泥基材料可视为由水泥膏、聚合体和界面过渡区(ITZ)组成的三相复合材料,它们之间的1、2。ITS通常被视为一个薄弱环节,因为它增加的孔隙度可以作为入侵物种3,4的通道,或为裂缝生长5,6,7,8,9,10,11提供更容易的途径。因此,对精确描述ITZ的特性进行评价和预测水泥基材料的宏观性能是十分感兴趣的。

为了研究ITZ,对它微观结构特征、形成机制和影响因子12、13、14的研究都采用了实验和数值方法。各种技术已经结合为ITZ表征,包括:机械测试,运输测试,汞入侵孔隙测量(MIP)测试15,16和纳米缩进17。人们普遍认为,IT主要是由墙体效应引起的,以及水膜、微出血、单侧生长和凝胶辛斯18。

随着近二十年来数字图像处理方法(DIP)的发展,可以定量确定信息源的形态特征(如体积分数、厚度和孔隙梯度)。基于使用带背散电子探测器(BSE)的扫描电子显微镜(SEM)对平面部分的检查,通过立体理论20,从2D结果中得出ITZ的三维(3D)特征。与SEM-BSE技术一样,纳米缩进技术也基于对抛光表面的检查,但它更侧重于现有阶段21的弹性模量。然而,在SEM-BSE分析和纳米缩进试验中,由于被检查的横截面很少从总表面22穿过正常方向,因此对ITZ厚度可能被高估。然而,结合荧光3D共聚焦显微镜,可以消除对ITZ的高估,获得真正的ITZ孔隙度和无水水泥含量

以往对影响因素的研究主要集中在水泥膏上,忽略了骨料的作用及其表面质地24、25、26。由于聚合的形状和形态特性已经广泛描述的基础上,从SEM或X射线计算机断层扫描(X-CT)27,28的数字切片的定量分析。然而,还没有开展以聚合表面纹理对伊茨区域形成影响的研究。

本文根据SEM-BSE图像的定量分析和K-means聚类算法,提出了一种研究聚合表面形态对ITZ微观结构形成的影响的协议。以球形陶瓷颗粒作为粗骨料制备模型混凝土样品。X-CT 用于在将样品减半之前大致确定颗粒在不透明水泥基质中的相对位置。对获得SEM-BSE图像的处理后,观察到了单聚合周围ITZ的不均匀分布。此外,还定义了描述像素级别的聚合表面纹理的索引表面粗糙度 (SR)。K-均值聚类算法最初用于信号处理领域,现在广泛用于图像聚类29,30,被引入建立表面粗糙度(SR)和孔隙度梯度(SL)之间的关系。

Protocol

1. 用单个陶瓷颗粒制备模型混凝土 模具制备 使用刷子清洁模具(25 毫米 x 25 毫米 x 25 毫米),并确保模具的内表面无杂质。 使用另一个刷子均匀地将柴油涂抹在模具的内表面,以便更容易脱模。注:在这里,我们没有使用普通模具进行砂浆或混凝土制备。由于陶瓷颗粒直径约15毫米,因此使用长度约30毫米的立方塑料模具进行样品制备。确保塑料模具的尺寸大于陶瓷颗粒…

Representative Results

对位于聚合方、聚合侧和聚合下方的 ITZ 区域的孔隙分布进行了比较,如图432所示。上表面上方的 ITZ 孔隙度似乎小于骨量侧面或上方,表明其密度较高,而聚合下方的 ITZ 始终由于微出血而最多孔。图 432显示,即使围绕相同的聚合,分布也是不均匀的。 为了研究聚合曲面形态的影响,手动捕获?…

Discussion

采用X-CT技术粗略确定陶瓷粒子的几何中心,以确保分析的表面通过粒子的赤道。因此,可以避免高估由2D伪影引起的ITZ厚度因此,获得结果的准确性在很大程度上取决于被检查表面的平坦度。通常,较长的磨削和抛光时间有助于表面充分光滑,以便进行测试。然而,由于水泥膏和陶瓷颗粒之间的硬度不同,长时间的磨削和抛光时间往往在两个阶段之间产生高度差异,在获得的B…

Declarações

The authors have nothing to disclose.

Acknowledgements

作者感谢国家重点研发项目(2017YFB0309904)、国家自然科学基金(授权号51508090和51808188)、973计划(2015CB655100)、国家重点实验室的财政支持。高性能土木工程材料 (2016CEM005)。同时,对江苏省建筑科学研究院和高性能土木工程材料国家重点实验室的资助项目表示高度赞赏。

Materials

Auto Sputter Coater Cressington 108 Auto/SE
Automatic polishing machine Buehler Phoenix4000
Brush Huoniu 3#
Cement China United Cement Corporation P.I. 42.5
Cement paste mixer Wuxi Construction and Engineering NJ160
Ceramic particle Haoqiang Φ15 mm
Cling film Miaojie 65300
Cold mounting machine Buehler Cast N' Vac 1000
Conductive tape Nissin Corporation 7311
Cup Buehler 20-8177-100
Cutting machine Buehler Isomet 4000
Cylindrical plastic mold Buehler 20-8151-100
Diamond paste Buehler 00060210, 00060190, 00060170
Diesel oil China Petroleum 0#
Electronic balance Setra BL-4100F
Epoxy resin Buehler 20-3453-128
Hardener Buehler 20-3453-032
High precision cutting machine Buehler 2215
Image J National Institutes of Health 1.52o
Isopropyl alcohol Sinopharm M0130-241
Matlab MathWorks R2014a
Paper Deli A4
Plastic box Beichen 3630
Plastic mold Youke a=b=c=25mm
Polished flannelette Buehler 242150, 00242050, 00242100
Release agent Buehler 20-8186-30
Scanning Electron Microscopy FEI Quanta 250
Scrape knife Jinzheng Building Materials CD-3
SiC paper Buehler P180, P320, P1200
Ultrasonic cleaner Zhixin DLJ
Vacuum box Heheng DZF-6020
Vacuum drying oven ZK ZK30
Vibrating table Jianyi GZ-75
Wooden stick Buehler 20-8175
X-ray Computed Tomography YXLON Y.CT PRECISION S

Referências

  1. Scrivener, K. L., Crumbie, A. K., Laugesen, P. The Interfacial Transition Zone (ITZ) Between Cement Paste and Aggregate in Concrete. Interface Science. 12 (4), 411-421 (2004).
  2. Scrivener, K. L. Backscattered electron imaging of cementitious microstructures: understanding and quantification. Cement and Concrete Composites. 26 (8), 935-945 (2004).
  3. Houst, Y. F., Sadouki, H., Wittmann, F. H. Influence of aggregate concentration on the diffusion of CO2 and O2. Concrete. , 279-288 (1993).
  4. Halamickova, P., Detwiler, R. J., Bentz, D. P., Garboczi, E. J. Water permeability and chloride ion diffusion in portland cement mortars: Relationship to sand content and critical pore diameter. Cement & Concrete Research. 25 (4), 790-802 (1995).
  5. Yang, Z., et al. In-situ X-ray computed tomography characterisation of 3D fracture evolution and image-based numerical homogenisation of concrete. Cement and Concrete Composites. 75, 74-83 (2017).
  6. Skarżyński, &. #. 3. 2. 1. ;., Nitka, M., Tejchman, J. Modelling of concrete fracture at aggregate level using FEM and DEM based on X-ray µCT images of internal structure. Engineering Fracture Mechanics. 147, 13-35 (2015).
  7. Königsberger, M., Pichler, B., Hellmich, C. Micromechanics of ITZ-Aggregate Interaaction in Concrete Part II: Stength Upscaling. Journal of the American Ceramic Society. 97 (2), 543-551 (2014).
  8. Shahbazi, S., Rasoolan, I. Meso-scale finite element modeling of non-homogeneous three-phase concrete. Case Studies in Construction Materials. 6, 29-42 (2017).
  9. Akçaoğlu, T., Tokyay, M., Çelik, T. Assessing the ITZ microcracking via scanning electron microscope and its effect on the failure behavior of concrete. Cement and Concrete Research. 35 (2), 358-363 (2005).
  10. Chang, H., Feng, P., Lyu, K., Liu, J. A novel method for assessing C-S-H chloride adsorption in cement pastes. Construction & Building Materials. 225, 324-331 (2019).
  11. Wang, P., Jia, Y., Li, T., Hou, D., Zheng, Q. Molecular dynamics study on ions and water confined in the nanometer channel of Friedel’s salt: structure dynamics and interfacial interaction. Physical Chemistry Chemical Physics. 20, 27049-27058 (2018).
  12. Ma, H., Li, Z. A Multi-Aggregate Approach For Modeling The Interfacial Transition Zone In Concrete. ACI Materials Journal. 111 (2), (2014).
  13. Yun, G., et al. Characterization of ITZ in ternary blended cementitious composites: Experiment and simulation. Construction & Building Materials. 41 (2), 742-750 (2013).
  14. Garboczi, E. J., Bentz, D. P. In Digital simulation of the aggregate-cement paste interfacial zone in concrete. International Conference on Electric Information and Control Engineering (ICEICE), 2011. , 196-201 (2011).
  15. Winslow, D. N., Cohen, M. D., Bentz, D. P., Snyder, K. A., Garboczi, E. J. Percolation and pore structure in mortars and concrete. Cement & Concrete Research. 24 (1), 25-37 (1994).
  16. Simões, T. . Mechanical Characterization of Fiber/Paste and Aggregate/Paste Interfaces (ITZ) in Reinforced Concrete with Fibers. , (2018).
  17. Xiao, J., Li, W., Sun, Z., Lange, D. A., Shah, S. P. Properties of interfacial transition zones in recycled aggregate concrete tested by nanoindentation. Cement and Concrete Composites. 37, 276-292 (2013).
  18. Bentz, D. P., Garboczi, E. J., Stutzman, P. E. Computer Modelling of the Interfacial Transition Zone in Concrete. Interfaces in Cementitious Composites. , 107-116 (1993).
  19. Kai, L., Wei, S., Changwen, M., Honglei, C., Yue, G. Quantitative characterization of pore morphology in hardened cement paste via SEM-BSE image analysis. Construction & Building Materials. 202, 589-602 (2019).
  20. Ondracek, G., Underwood, E. Quantitative stereology. Journal of Nuclear Materials. 42 (2), 237-237 (1972).
  21. Xu, J., Wang, B., Zuo, J. Modification effects of nanosilica on the interfacial transition zone in concrete: A multiscale approach. Cement and Concrete Composite. 81, 1-10 (2017).
  22. Zhu, Z., Chen, H. . Overestimation of ITZ thickness around regular polygon and ellipse aggregate. , 205-218 (2017).
  23. Head, M. K., Wong, H. S., Buenfeld, N. R. Characterising aggregate surface geometry in thin-sections of mortar and concrete. Cement and Concrete Research. 38 (10), 1227-1231 (2008).
  24. Gao, Y., De Schutter, G., Ye, G., Tan, Z., Wu, K. The ITZ microstructure, thickness and porosity in blended cementitious composite: Effects of curing age, water to binder ratio and aggregate content. Composites Part B: Engineering. 60, 1-13 (2014).
  25. Erdem, S., Dawson, A. R., Thom, N. H. Influence of the micro- and nanoscale local mechanical properties of the interfacial transition zone on impact behavior of concrete made with different aggregates. Cement and Concrete Research. 42 (2), 447-458 (2012).
  26. Elsharief, A., Cohen, M. D., Olek, J. Influence of aggregate size, water cement ratio and age on the microstructure of the interfacial transition zone. Cement & Concrete Research. 33 (11), 1837-1849 (2003).
  27. Pan, T., Tutumluer, E. Quantification of Coarse Aggregate Surface Texture Using Image Analysis. Journal of Testing & Evaluation. 35 (2), 177-186 (2006).
  28. Erdogan, S. T., et al. Three-dimensional shape analysis of coarse aggregates: New techniques for and preliminary results on several different coarse aggregates and reference rocks. Cement & Concrete Research. 36 (9), 1619-1627 (2006).
  29. Santos, B. O., Valença, J., Fowler, D. W., Saleh, H. A. Livings patterns on concrete surfaces with biological stains using hyperspectral images processing. Structural Control and Health Monitoring. , (2019).
  30. Santos, B. O., Valença, J., Júlio, E. In Classification of biological colonization on concrete surfaces using false colour HSV images, including near-infrared information. Optical Sensing and Detection V, International Society for Optics and Photonics. , 106800 (2018).
  31. Stock, S. R. Recent advances in X-ray microtomography applied to materials. International Materials Reviews. 53 (3), 129-181 (2013).
  32. Lyu, K., Garboczi, E. J., She, W., Miao, C. The effect of rough vs. smooth aggregate surfaces on the characteristics of the interfacial transition zone. Cement and Concrete Composites. 99, 49-61 (2019).
  33. Wong, H. S., Head, M. K., Buenfeld, N. R. Pore segmentation of cement-based materials from backscattered electron images. Cement & Concrete Research. 36 (6), 1083-1090 (2006).
  34. Liao, K. -. Y., Chang, P. -. K., Peng, Y. -. N., Yang, C. -. C. A study on characteristics of interfacial transition zone in concrete. Cement and Concrete Research. 34 (6), 977-989 (2004).
  35. Barnes, B. D., Diamond, S., Dolch, W. L. The contact zone between portland cement paste and glass “aggregate” surfaces. Cement & Concrete Research. 8 (2), 233-243 (1978).
  36. Hamerly, G., Elkan, C. Alternatives to the k-means algorithm that find better clusterings. Proceedings of the eleventh international conference on Information and knowledge management, ACM. , 600-607 (2002).
  37. Celebi, M. E., Kingravi, H. A., Vela, P. A. . A comparative study of efficient initialization methods for the k-means clustering algorithm. , 200-210 (2013).
  38. Lu, Y., et al. Three-dimensional mortars using real-shaped sand particles and uniform thickness interfacial transition zones: Artifacts seen in 2D slices. Cement and Concrete Research. , (2018).
  39. Gao, Y., De Schutter, G., Ye, G., Huang, H., Tan, Z., Wu, K. Porosity characterization of ITZ in cementitious composites: Concentric expansion and overflow criterion. Construction and Building Materials. 38, 1051-1057 (2013).
  40. Celebi, M. E., Kingravi, H. A., Vela, P. A. A comparative study of efficient initialization methods for the k-means clustering algorithm. Expert Systems with Applications. 40 (1), 200-210 (2013).

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Lyu, K., She, W. Determination of Aggregate Surface Morphology at the Interfacial Transition Zone (ITZ). J. Vis. Exp. (154), e60245, doi:10.3791/60245 (2019).

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