Determinatin of durability-enhancing admixtures in concrete by thermal desorption and pyrolysis gas chromatography-mass spectrometry

摘要

Two methods involving thermal desorption andpyrolysis gas chromatography-mass spectrometry are describedfor the determination of two durability-enhancing admixtures, acorrosion inhibitor and a shrinkage reducing agent (SRA) inhardened portland cement mortar and concrete. The corrosioninhibitor, based on calcium nitrite, is selectively measured by thein situ pyrolytic conversion of 2-aminobi-phenyl to 2-phenylphenol. The SRA, which consists of a mixture of isomericglycol and ether compounds, can be thermally desorbed directlyfrom powdered concrete. For both durability-enhancing agents,the recovery rate generally exceeds 93% with no interferenceevident from several common chemical admixtures. Cementcomposition does not appear to significantly affect desorptionefficiency for the SRA additive. Thermal desorption and pyrolysisgas chromatography are shown to be rapid, selective, and highlyconvenient methods for both qualitative and quantitativeestimates of two important chemical admixtures.