水泥基材料界面过渡区的压汞法联合X射线断层扫描表征

Characterization of ITZ in Cement–based Materials by Mercury Intrusion Porosimetery and X-ray Computed Tomography

水泥基材料基体和骨料之间的界面过渡区是影响材料力学性能和传输性能的薄弱区域,因此解析骨料周围的界面过渡区一直是混凝土研究的重要专题。由于分辨率的限制,工业X射线断层扫描技术(XCT)通常难以解析界面过渡区的三维形貌。而当过渡区孔隙中充满汞后,由于汞的高X射线吸收系数,界面过渡区XCT图像衬度显著提升。利用这一原理,提出压汞联合XCT的可视化表征方法,以石英玻璃棒为骨料制备了连通的水泥–骨料界面过渡区样品。结果表明:压汞后残余汞滴残留在界面过渡区,对界面过渡区的表征起到了显影增强作用,解析出了界面过渡区的三维孔隙结构。为探索水泥基多孔材料基体与集料界面过渡区孔隙分布规律提供全新研究思路。

Interfacial transition zone(ITZ)between cement matrix and aggregate is regarded as a weak phase that affects the mechanical properties and durability performance of concrete.Therefore,resolving ITZ around aggregate has always attracted great attentions in concrete research.Due to the limitation of resolution,using industrial X-ray computed tomography(XCT)to address three-dimensional(3D)morphology of ITZ becomes a challenge.However,the extremely high X-ray attenuation of mercury can greatly increase the contrast of XCT images when the pores of ITZ are filled with mercury.This regime allows visual characterization of ITZ for cement-based materials after mercury intrusion porosimetery(MIP).A glass rod was used as an aggregate to fabricate connected matrix-aggregate ITZs.The results show that the residual mercury droplets in pores after MIP enhance the gray values of ITZ,thus addressing the 3D structure of ITZ.The findings provide a new path to exploring the pore structure of matrix-aggregate ITZ in cement-based materials.