在界面过渡区（ITZ）的聚合曲面形态测定
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…
Divulgazioni
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 |
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Citazione di questo articolo
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).