Main Entry: lai·tance
              Pronunciation: 'lA-t&n(t)s
              Function: noun
              Etymology: French, from lait milk, from
              Latin lact-, lac -- more at GALAXY
              Date: circa 1902 : an accumulation of fine particles on
the  surface of fresh concrete due to an
              upward movement of water (as when excessive mixing water
is used)

My suspicion is that this is not what the engineer is referring to