Where is Concrete with Chert Aggregate found?
Concrete (artificial rock) with Chert (sedimentary rock)
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Open the appConcrete with Chert Aggregate occurs in specific geological environments. Knowing where to look, and in what kind of rock, is the difference between going home empty-handed and finding a great specimen.
Where to find Concrete with Chert Aggregate
Construction Sites
Anywhere concrete is being poured or has been used for infrastructure, buildings, or pavements. Chert-bearing concrete is more common in regions where chert is an abundant and economically viable aggregate source.
Quarries and Aggregate Plants
Sources of chert aggregate for concrete production. These locations will supply the raw materials, not the finished concrete.
Demolition Sites
Where old concrete structures are being removed, providing samples of aged concrete that may contain chert aggregate.
Collecting tips
- Visual Inspection. Look for angular to sub-rounded, often light-colored (but can be dark) aggregate particles embedded within a gray cement matrix. Chert often has a distinctive conchoidal fracture when broken.
- Hardness Test. Chert is hard (Mohs 7), so it will scratch glass and steel. The cement paste is much softer (Mohs 3-4). This difference can be felt or observed when scratching the material.
- Acid Test (for Chert identification). While not for the concrete itself, a drop of dilute hydrochloric acid (HCl) will not react with chert (SiO2), distinguishing it from limestone (CaCO3) aggregates which would effervesce. Be cautious with acid.
- Observe Deterioration. In older concrete structures, look for signs of ASR (Alkali-Silica Reaction) such as map cracking, gel exudation, and pop-outs, which are indicative of reactive aggregate like chert.
Quick Check
- Color:
- Gray matrix with variable colored aggregate (often light gray, brown, or black)
- Luster:
- Dull to earthy (matrix), dull to waxy/vitreous (chert aggregate)
- Streak:
- White (for both cement paste and chert)
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