Characterization of test specimens produced in reduced size for X-ray microtomography (µ-CT) tests

Abstract The need to use reduced sample sizes, in order to attain improved spatial resolution in (µ-CT) tests applied in Portland cement composites, makes researchers perform the fractionation of materials to obtain samples with dimensions compatible with the capacity of the scanning equipment, which might cause alterations in the microstructure under analysis. Therefore, a test specimen (TS) with dimensions compatible with the scanning capacity of a microtomography system that operates with an X-ray tube and voltage ranging from 20 to 100 kV was proposed. Axial compression strength tests were made and their total porosity was assessed by an apparent density and solid fraction density ratio, which were obtained by means of mercury and helium pycnometry and µ-CT technique, respectively. The adoption of that TS has shown to be viable for providing a sample with a higher level of representation.

摘要 为在针对硅酸盐水泥基复合材料的显微CT（µ-CT）测试中实现更高空间分辨率，需缩减样本尺寸，这要求研究人员对材料进行分样，以获取与扫描设备性能匹配的试样，但该操作可能会改变所分析的微观结构。为此，本研究提出了一种适配于采用工作电压范围20~100kV的X射线管的显微层析成像系统扫描能力的试样（TS）。研究人员开展了轴向抗压强度试验，并通过汞置换法、氦置换法密度测试以及µ-CT技术分别获取表观密度与固相密度的比值，以此评估试样的总孔隙率。结果表明，采用该试样可获得代表性更强的测试样本，具备实际应用可行性。