Petrographic Thin Section
Definition
A slice of material ground to 30 micrometres and mounted on a glass slide for transmitted polarised light microscopy; the standard tool for identifying mineral phases, estimating proportions, and mapping microstructural features in concrete and mortar.
- Section thickness
- About 30 micrometres
- Mounting
- Glass microscope slide
- Technique
- Transmitted polarised light microscopy
- Application
- Mineral phase identification in concrete and mortar
Common questions
What can a thin section reveal beyond simple mineral composition?+
Under polarised light an examiner can estimate the relative proportions of mineral phases, map microstructural features such as cracking or aggregate-paste bonding, and identify alteration products that indicate weathering, fire exposure or chemical attack.
What is a limitation of relying on thin sectioning alone?+
It captures only a two-dimensional slice of a three-dimensional material, so features like void distribution or fracture connectivity may be under- or over-represented unless multiple sections or complementary imaging are used.
Related terms
- Aggregate
- The granular filler (sand, gravel, crushed rock) that occupies 60-80% of a concrete volume; its mineralogy, grain shape, and size distribution are...
- Calcium Silicate Hydrate (C-S-H)
- The principal binding phase produced when Portland cement reacts with water; a gel-like material that gives concrete most of its strength and...
- Carbonation Front
- The boundary in concrete where atmospheric CO2 has converted portlandite to calcite; the depth of this front (measured in millimetres) is used...
- Ettringite
- A calcium sulfoaluminate hydrate that forms early in cement hydration and can re-form later from delayed sulfate attack; its presence or alteration...
- 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...