Three Dimensional Fracture Process Zone Detection in Concrete

本研究项目的目的是探索 正电子湮没器光谱（PAS）技术的映射 三维缺陷分布周围的延伸 脆性材料中的裂纹，如混凝土和结构陶瓷。 PAS是一种非破坏性的原位方法，用于量化隐藏的 表面和缺陷小至1埃（1/10，000，000，000 米）的多孔介质中。 提议者钟博士和他的 合作者郑博士认为，考绩制度也可以用来衡量 微米（1/1，000，000米）量级的更大缺陷 致密陶瓷和毫米（1/1,000米）的混凝土。 既不 X射线或超声波技术，目前正在 发展，提供足够的分辨率，这种无损 检查（NDI）。 脆性材料中裂纹尖端前的大缺陷 材料会降低其韧性，但云的小缺陷 在裂纹尖端周围和后面将增加其韧性。 由于这种受控的缺陷增加了脆性材料的韧性， 材料，必须确定这些缺陷的大小和位置 被人所知 PAS技术可以为我们提供一种NDI程序， 这个目的。 怀俄明州大学的Chong博士因 他在岩石和混凝土断裂方面的专业知识和郑博士， 密苏里州，是众所周知的，他在PAS的工作。 合作社 这两位教授之间的研究 为这次探索性研究提供了一个最佳安排。

The objective of this research program is to explore the possible use of the Positron Annihilator Spectroscopy (PAS) technique for mapping the three-dimensional defect distribution surrounding an extending crack in brittle materials, such as concrete and structural ceramics. PAS is a non-destructive and an in-situ method for quantifying hidden surfaces and defects as small as one angstrom (1/10,000,000,000 meter) in porous media. The proposer, Dr. Chong, and his collaborator, Dr. Cheng, feel that PAS can also be used to measure much larger defects of the orders of micron (1/1,000,000 meter) in dense ceramics and millimeter (1/1,000 meter) in concrete. Neither the X-ray nor the ultrasonic techniques, which are currently under development, provide adequate resolution for such nondestructive inspection (NDI). Large defects ahead of the crack tip in a brittle material will decrease its toughness but clouds of small defects surrounding and behind the crack tip will increase its toughness. Since such controlled defects increase the toughness of a brittle material, it is imperative that the size and location of these defect be known. The PAS technique may provide us with a NDI procedure for this purpose. Dr. Chong, University of Wyoming, is well known for his expertise in rock and concrete fracture and Dr. Cheng, University of Missouri, is well known for his work in PAS. The cooperative research between these two faculty members provide an optimum arrangement for this exploratory study.