Characterizing cement types in end-of-life concrete: A practical approach using handheld X-ray fluorescence

Reducing CO 2 emissions from concrete production requires effective recycling of cement, particularly its clinker component. Significant emission reductions depend on innovative techniques that extract high-quality cement fractions from recycled concrete, beginning with source separation strategies before demolition. This study developed a practical measurement approach using handheld X-ray fluorescence (HXRF) to identify cement types (i.e. cement classifications such as CEM I, CEM II/B-V, CEM III/B) in End-of-Life concrete. The research was conducted in two phases: First, laboratory testing of seven powder samples (milled river gravel and sand, three cement types: CEM I, CEM II/B-V and CEM III/B along with blast furnace slag and fly ash) and three cement paste prism types containing the three cement types established optimal measurement parameters and assessed moisture influence. Second, field measurements were taken on outdoor concrete blocks, containing the three cement types, after one year of weather exposure. Measurements were conducted on both the exposed surface and subsurface layers (after removing 0.1–5 mm of material). Results showed that powder samples can be accurately characterized with 10-second measurements, while concrete blocks require at least 20 s. HXRF measurements demonstrated good reproducibility with low coefficients of variation (CV) values, ensuring reliable cement type identification. Surface measurements are reliable only when the concrete is unaltered: coatings, paint, or weathering negatively affect accuracy, necessitating removal of the surface layer. Cement types were successfully distinguished using oxide concentrations (Al₂O₃, Fe₂O₃, P₂O₅, MgO) and their ratios (CEM III/B: Al 2 O 3 /Fe 2 O 3 > 9.0, MgO/Fe 2 O 3 > 3.0, MgO/CaO > 0.11, Fe 2 O 3 /Al 2 O 3 < 0.11 and Fe 2 O 3 /CaO < 0.04; CEM II/B-V: P 2 O 5 /CaO > 0.005 and P 2 O 5 /Fe 2 O 3 > 0.1; CEM I: P 2 O 5 /CaO < 0.005 and P 2 O 5 /Fe 2 O 3 < 0.1). This study demonstrates that handheld XRF enables fast and reliable in-situ identification of the three studied cement types, supporting improved source separation and cement recycling strategies. • Handheld XRF enables rapid on-site identification of cement types. • Surface layer removal needed, as surface coatings and weathering reduce accuracy. • Reliable field analysis requires a minimum of 20-second measurement time. • Cement types are distinguished using oxide concentrations and their ratios.