Petrography

Concrete and Aggregate Petrography

What is Petrography?

Petrography is a branch of geology in where rocks and minerals are analysed using various types of microscopes. The data collected yields information regarding mineralogy, textures, associations, microstructures, and more.

How is this applied to concrete and aggregate?

Microscopic issues can cause large scale problems. Petrography is utilised to evaluate concrete for ASR/ACR, DEF, durability, cement type/hydration, geopolymer cement, cracking/microcracking, chemical attack, fire damage, leaching, scaling/spalling, finishing issues, freeze-thaw damage, and much more.

The technique is used as a screening tool for coarse and fine aggregate to evaluate bulk material for secondary minerals present, ASR potential, and/or suitability for use in concrete.

Whether conducting a durability assessment, determining structure life, remediation work, or other types of investigations, having a complete understanding of the material at the microscopic level will pay dividends in understanding its performance at the macro scale.

Microanalysis Australia Offers the Following Standardised Petrographic Tests:

ASTM C856 – Standard Practice for Petrographic Examination of Hardened Concrete

ASTM C295 – Standard Guide for Petrographic Examination of Aggregates for Concrete

AS 1141.26 – Secondary Minerals Content in Igneous Rocks

AS 1141.65 – Alkali Aggregate Reactivity: Qualitative Petrological Screening for Potential ASR

Petrographic testing independent of these standards may also be conducted

Geological Petrography

Petrography is key in determining the formation, alteration, and weathering processes that have occurred to geologic samples. Petrographic analysis collects data regarding the sample mineralogy, texture, mineral associations, and more in order to classify rock samples and to determine their geologic history. Having an understanding of the geologic history of an area of interest can lead to more streamlined exploration in mining, quarrying, oil and gas, and more.

Thin Sectioning

Petrographic analysis requires thin sections to be made. A thin section is a 30 µm thick slice of rock, minerals, concrete, or other material that is mounted to a glass microscope slide. Microanalysis Australia offers thin section services as a subset of our petrographic services.

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  • Royal Australian Chemical Institute
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