Q.: Is there a test for determining whether or not fly ash has been used in concrete? If so, can the test show how much was used?
A.: A petrographer can readily tell if fly ash is present in a sample of the hardened concrete. The exact amount is difficult to determine, but the petrographer can probably tell by visual methods if there was 1% to 2% or 10% to 15% fly ash by volume of cement. If samples of the fly ash used were available, a more precise estimate could be obtained using quantitative chemical analysis.