Check it out 3 chapters.

http://www.concretepumping.com/dictionary/index.php/Main_Page

Next Chapter will be on gap graded sands, mud flashing, lean mix & lean fill pumping.

With my line pump I need a "pump mix"  I always check with the plant after people order it.  Friday we pumped 100 yards for a mud slab. I called the supplier and they had a 3000 pump mix ordered, went great.  They called this morning about a sump pit that had been blocked out on Fridays pour.  I was busy and said have the mud there at 2.  Key word here busy.  2 pm mud arrives and we primed out ok but then it locked up.  Driver showed the ticket and it was just a pea gravel mix.  I guess it was my fault for not following through like I always did.  I was allowed to wet it up and get the job done.  I guess it is important that we know what we are pumping and take control without stepping on any higher ups.