During mixing of the concretes with the C-LWA no segregation was evident. This could be also confirmed by inspecting the cut surfaces of concrete cubes -no accumulation of the lighter C-LWA at the upper surfaces of concrete cubes was found, see Fig. . Also, the pellets appeared all as rounded particles and no fracturing of the single pellets could be observed, as also evidenced in the X-ray CT (see section 3.2). The concrete with C-LWA added in their cured state (i.e. without presaturation) had significantly higher air content, see Table and Fig. and. This was mainly due to the air escaping the C-LWA pellets as they absorbed water during mixing of concretes. However, no concentration of the air bubbles around the C-LWA was evident. The entrained air was on the contrary rather well distributed in the bulk of concrete. The concrete with the saturated C-LWA had similar workability as the reference concrete, which confirms that the amount of preabsorbed water calculated based on the absorption of 0.19 g/g was correct. For the concrete with C-LWA added dry, a significant loss of workability was observed. In this case, superplasticizer was necessary to reach the desired spread of the concrete (see Table ).