Characterizing gas bubble size distribution of laboratory foamed cement using X-ray micro-CT

The objectives of this study are to use micro-computed tomography (micro-CT) to elucidate the influencing factors of the microstructure of laboratory foamed cement and develop statistical models to quantify the gas bubble size distributions. During this study, foamed cement slurries were prepared using sealed foam cement mixers at various operating conditions. The influences of shear rate, mixing energy, base cement slurry composition, blender geometry, and applied pressure on the gas bubble size distribution of set foamed cement were investigated. Test results indicate foam quality and gas pressure are the primary determining factors of gas bubble size in foamed cement. The gas bubble size in foamed cement produced by a sealed foam mixer approximately follows the normal distribution. For samples generated with a standard multiblade blender at atmospheric condition, the mean and standard deviation of gas bubble size distribution increase exponentially with increasing foam quality. A dramatic decrease in gas bubble size is observed with increasing gas pressure. On the other hand, variations in mixing energy, shear rate, base slurry composition, and blender geometry have relatively little effect on the microstructure of the foamed cement within the range investigated.