Aggregate
Definition
The granular filler (sand, gravel, crushed rock) that occupies 60-80% of a concrete volume; its mineralogy, grain shape, and size distribution are controlled by the quarry source and serve as a geographic and provenance discriminator.
- Materials
- Sand, gravel, crushed rock
- Volume share of concrete
- 60 to 80 percent
- Discriminating properties
- Mineralogy, grain shape, size distribution
- Forensic use
- Geographic and quarry provenance discriminator
Common questions
How can aggregate composition point to a specific location?+
Local quarries draw from geologically distinct rock sources, so the mineral suite and grain morphology in a concrete sample can be compared against regional quarry reference collections to narrow where the material was produced or poured.
Does the cement paste itself carry the same discriminating value as the aggregate?+
Less so. Cement is manufactured to fairly uniform industrial specifications regardless of plant location, while aggregate directly reflects the local geology it was mined from, making it the more informative fraction for provenance work.
Related terms
- 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...
- Petrographic Thin Section
- A slice of material ground to 30 micrometres and mounted on a glass slide for transmitted polarised light microscopy; the standard tool...
- 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...