Characterizing air pores in autoclaved aerated concrete

The air pore structure of an autoclaved aerated concrete (AAC) sample with 0.30 kg/dm³ apparent density was investigated in this work. Based on computer tomography (CT) and image analysis the air pores between 100 mm to 5 mm in diameter have been characterized with 3D image analysis. The mostly spherical but highly interconnected pores could be successfully separated by a watershed algorithm. The size distribution of these reconstructed ""single"" pores was found to be bimodal. An examination reveals it to be a kind of densest sphere packing mainly of two pore size classes, with a similar characteristic as densest regular sphere packing, with the second biggest pore class filling the octahedral interstitial places of the dense sphere packing of the largest pores. The method applied here, CT with extensive 3D image analysis, proofed to be a detailed technique to characterize air pore structure of AAC, even at low densities. The image analysis methods may easily be improved to get more quantitative information on AAC specific pore characteristics, like the crack structure produced during blowing.