Sammendrag
X-ray computer tomography (“CT scanning”) is well-suited for detecting air-void content in concrete. However, there is a possibility of obtaining large variations depending on several scanning- and segmentation settings. The sample size, tube voltage, tube current, and voxel size are the main scanning setting parameters causing variations. Small samples give a high spatial resolution; however, it is unclear if the small sample (sawn or cored) contains the same air-void system as the original sample. Thus, this study first reviews how scanning and segmentation affect air-void content in hardened concrete. Then we determined the air-void system in a big sample (100 by 100 by 20 mm) of air-entrained fly ash concrete using a Zeiss Metrotom 1500 CT scanner. Then, the specimen was cut into nine small cubes, and the air-void system was analyzed applying the software VGStudio Max 3.0 in terms of total air-void volume, specific surface area, and spacing factor. The results indicated a good agreement between all these parameters for nine small cubes. The variation observed between the large sample and small cubes were determined and discussed regarding the difference in voxel size (resolution).
Vis fullstendig beskrivelse
