Petrographic Analysis

Petrographic analysis is the microscopic examination of concrete and masonry samples prepared as thin sections (slices approximately 0.03mm thick mounted on glass slides). Under polarised light microscopy, the internal structure of the material is revealed in detail, aggregate mineralogy, cement matrix condition, air void system, crack patterns, and evidence of deleterious chemical reactions. This level of detail is not available from any other test method.

For structural investigation, petrographic analysis answers questions that compressive strength testing cannot: why is the concrete in its current condition, and what is likely to happen next? Evidence of alkali-silica reaction (ASR), delayed ettringite formation (DEF), sulfate attack, freeze-thaw damage, and fire damage is visible in thin section and can be identified, classified, and assessed for severity by an experienced petrographer.

At the Victory Hotel, petrographic analysis of core samples from the 1855 colonial masonry and early concrete elements provided critical information about original construction materials, lime mortar composition, aggregate sources, and cement types, that directly informed the specification of compatible repair materials. For heritage structures, petrographic analysis is the definitive method for understanding original construction and ensuring that modern repairs are materially compatible.

TRSC submits samples to NATA-accredited petrographic laboratories and works with specialist petrographers who understand the structural engineering context of the analysis. Petrographic reports are integrated with other investigation findings, compressive strength, chloride content, carbonation depth, to build a complete picture of the concrete or masonry condition and its implications for structural performance.