Pozzolan
Definition
A silica- or alumina-rich material (fly ash, silica fume, volcanic ash) that reacts with portlandite to form additional C-S-H gel; used as a cement blend component.
- Composition
- Silica- or alumina-rich material
- Common sources
- Fly ash, silica fume, volcanic ash
- Reaction partner
- Portlandite (calcium hydroxide)
- Product formed
- Additional C-S-H gel
- Use
- Blended cement component
Common questions
Why is pozzolan content relevant in forensic building-material comparison?+
Blend ratios and pozzolan type vary between cement sources and manufacturing batches, so their presence and proportion in a hardened concrete or plaster sample can help link or exclude a sample against a suspected source or match debris to a specific pour or product line.
How is pozzolan content detected in a set sample?+
Analysts typically use techniques such as XRF, SEM-EDS, or petrographic thin-section microscopy to identify the silica or alumina-rich phases and secondary C-S-H formed by the pozzolanic reaction, distinguishing blended cement from plain portland cement.
Related terms
- ASTM C150
- US standard specifying Portland-cement composition limits and performance requirements by type (I through V); referenced in forensic mineral-phase characterisation.
- Calcium Sulphate Hemihydrate
- CaSO4 . 1/2 H2O; produced by heating gypsum, rehydrates to gypsum on setting; the basis of plaster of Paris and most interior...
- Clinker
- The nodular intermediate product of Portland-cement manufacture, consisting of C3S, C2S, C3A and C4AF mineral phases before grinding.
- ENFSI ENG-FG1
- The European Network of Forensic Science Institutes' guidelines for forensic geological evidence, published in 2018 by the Expert Working Group on Forensic...
- Ettringite
- A calcium sulfoaluminate hydrate that forms early in cement hydration and can re-form later from delayed sulfate attack; its presence or alteration...
- FTIR (Fourier Transform Infrared Spectroscopy)
- A vibrational spectroscopy technique used in toner analysis to identify the polymer backbone and functional group composition of toner binder material; ATR...
- Portland Cement
- A hydraulic binder produced by firing calcium and silica sources at 1450°C; the four clinker phases (C3S, C2S, C3A, C4AF) hydrate on...
- Portlandite
- Calcium hydroxide (Ca(OH)2) crystallised during cement hydration; a bright birefringent phase visible in thin section that dissolves progressively as concrete carbonates, providing...
- Rietveld Refinement
- A full-pattern fitting method for XRD quantification that models the entire diffractogram using crystal structure data for each phase, adjusting phase abundances...
- SEM-EDS
- Scanning electron microscopy with energy-dispersive X-ray spectroscopy; provides elemental composition of each paint layer at 1-5 µm spatial resolution.
- XRD (X-Ray Powder Diffraction)
- Analytical technique identifying crystalline phases by their unique d-spacing pattern; primary method for phase-composition quantification in building materials.