Determination of grinding aids in portland cement by pyrolysis gas chromatography-mass spectrometry

Abstract The pyrolysis of Portland cement followed by gas chromatography/mass spectrometry is described for the determination of chemical additives interground with cement clinkers known as grinding aids. This technique, coupled with in situ derivitization using BSTFA-TMCS reagent, has been found to be readily applicable for detecting phenol, along with five glycol and alkanolamine-type compounds in cement. The recovery rate was found to be highly dependent upon the grinding process and the binding capacity of the various additives. Using a relatively short grinding process conducted at ambient temperature, most of the additives tested can be recovered at greater than 85% of their originally added concentration. However, in the case of a longer, more intense grinding procedure conducted at 105°C, only phenol had recovery rates greater than 50%. The formation of salts or stable complexes between the grindings aids and cations at the freshly fractured cement surfaces, is proposed as the major cause of the variable recovery rates for the various grinding aid compounds.