Besides increasing workability, adding the correct amount of AEA during concrete mixing improves its resistance to cracking during freeze and thaw cycles.
However, cement and components of fly ash adsorb AEA’s to different extents, making it more difficult to routinely impart the correct amount of entrained air into concrete.
The added AEA leads to foam formation on top of the liquid surface, which initially behaves in an unstable manner.
Adding diluted AEA one drop at a time is the most accurate way to measure the foam index, especially when trying to develop your ability to duplicate the test.
When bubbles break they produce unique acoustic signatures, the dynamic properties of which are measured by the detectors incorporated into the AFIT instrument.