Analyzing the Mineral Composition of Concrete

Samuel was looking for recommendations for the analysis of the mineral composition of concrete. Dr. Gaines offered advice when using either XRF or ICP for the analysis.

Dear Samuel,

I'm going to assume that you have either XRF or ICP instrumentation.

The industry norm for the analysis of cement involves a fusion of the sample with a 4:1 mixture of lithium metaborate and lithium tetraborate. The fusion method involves accurately weithing 1.5 grams of sample and 7.5 grams of the flux into a Pt alloy crucible and fusion in a laboratory muffle furnace or a gas flame (commercially available for this purpose).

If you are using XRF then the bead that is formed is analyzed using standards of known composition prepared in the same way. If ICP is used, the fuseate (here use a 1 gram sample fused with 10 grams of flux) is dissolved in 5 % nitric acid and diluted to a volume of 2 liters (smaller sample and flux sizes can be used so long as ratios are maintained) and analyzed using matrix matched standards. The following elements are determined and reported as the oxides: CaO, Al2O3, Na2O, MgO, SiO2, Fe2O3, Mn2O3, TiO2, P2O5, SO3 and K2O. Typically, the determination of free lime is made according to BS 4550 Part II. Analytical methods are published in BS 4550 and EN 196.

Good luck with your analysis.

Serving you in chemistry,

Paul R. Gaines, Ph.D.
CEO of Inorganic Ventures & Fellow Chemist

DISCLAIMER: Advice offered by the chemists at Inorganic Ventures is intended for the individual posing the question. Feel free to contact us to verify whether these suggestions apply to your unique circumstances.