I have added water and seen air increase slightly, but is an increase of 1.5% after the addition of 10 gallons to a 9 yard load normal? Or are we dealing with a product that has something else going on?
Air increases % can vary with the slump of concrete, the speed of mixing and the admixtures present in mix. One load of concrete may be an isolated case but I do not consider it too unusual though a little high.
Air will come out of the concrete as it is mixed, so if you sample at different points in the load, you will get diffent AE contents fro the same batch in the same truck