Abstract
This study aims to measure the air content in sprayed concrete specimens using CT scanning. Macro
pores can influence mechanical, permeability, and thermophysical properties of sprayed concrete.
Concrete panels were sprayed using full-scale equipment with a 7% alkali-free accelerator (by
equivalent binder mass), with distances (1.5 m, 2.5 m, 3.5 m) and angles (90 deg, 67 deg, and 45 deg)
from the nozzle to the application surface. After hardening, cores were drilled (100 mm diameter x
150 mm height) and scanned by a Zeiss Metrotom 1500 CT scanner. To limit scanning errors, a region
of interest (ROI) of 85 mm x 150 mm was selected from each core, and macro pore content was
analyzed by VGStudio Max 3.0 software. The results show total macro void contents and shape
characteristics of macro-voids. The CT scanning result depends on the resolution, and macro pore
content results are compared with those measured by image analysis on polished surfaces and by PF-test.
pores can influence mechanical, permeability, and thermophysical properties of sprayed concrete.
Concrete panels were sprayed using full-scale equipment with a 7% alkali-free accelerator (by
equivalent binder mass), with distances (1.5 m, 2.5 m, 3.5 m) and angles (90 deg, 67 deg, and 45 deg)
from the nozzle to the application surface. After hardening, cores were drilled (100 mm diameter x
150 mm height) and scanned by a Zeiss Metrotom 1500 CT scanner. To limit scanning errors, a region
of interest (ROI) of 85 mm x 150 mm was selected from each core, and macro pore content was
analyzed by VGStudio Max 3.0 software. The results show total macro void contents and shape
characteristics of macro-voids. The CT scanning result depends on the resolution, and macro pore
content results are compared with those measured by image analysis on polished surfaces and by PF-test.