Petrographic examination

Petrographic examination

 Petrographic examination is the microscopic examination of thin sections of concrete cores to identify the mineralogy and constituents of a concrete or render along with identifying any degradation present.

A petrographic report provides details including:

  • Type, proportions, grading, shape and condition of aggregates
  • Presence of deleterious aggregate(s)
  • Cement type
  • Presence of additives such as fly ash
  • Depth of carbonation
  • Water / cement ratio
  • Degree of hydration
  • Microporosity
  • Total void content
  • Presence of air entrainment
  • Size and distribution of voids
  • Void lining
  • Microfracturing

 

Along with the above, petrographic examination is frequently used to identify processes such as:

  • Alkali silica reaction (ASR) and alkali carbonate reaction (ACR).
  • Sulfate attack by delayed ettringite formation (DEF).
  • The Thaumasite form of sulfate attack (TSA).
  • Presence and extent of fire damage to concrete.
  • Presence and extent of cracking from structural, corrosive or alternative causes.

Sections for examination can be prepared from lump samples available, but ideally are taken from cores, typically of 50 to 100mm diameter, extracted from the concrete.

Nicholls Colton can attend site to remove cores for examination and arrange the subsequent examination of the concrete to suit your specific requirements.