Petrographic analysis is a diagnostic tool for examining failures in concrete.
Once onsite, we can carry out an initial visual examination of the area in order to ascertain possible causes of the problem and to determine the best position for taking samples. Our engineers can take core samples and return them to the laboratory where thin sections will be prepared for examination using Scanning Electron Microscopy (SEM) and Polarized Light Microscopy (PLM).
Petrographic analysis is carried out in accordance with both European and American standards: BS 1881-211:2016, ASTM C295, ASTM C856 and ASTM C457.
Benefits of petrographic examination include:
- Determining the present condition of previously placed concrete so that the decision to re-use or replace can be decided
- Establishing the root cause of surface scaling, spalling, aggregate pop-outs and abrasion
- Defining cracks by type and uncovering crack mechanisms
- Explaining causes of concrete degradation; primary mechanisms are:
- Alkali-Silica Reaction (ASR)
- Alkali-Carbonate Reaction (ACR)
- Sulfate attack
- Effects of chemical attack (including chlorides)
- Assessing the entrained air content
- Establishing the water/cement ratio
- Determining the density, absorption and volume of permeable voids (as defined in ASTM C642)
- Revealing the root cause(s) of low compressive strength with key milestones at 7, 28 and 56 days
- Comparing hardened concrete to known mix designs
- Assessing fire damage.
Forensic analysis can be supplemented by additional techniques which also include, but are not limited to chemical analysis, SEM and X-Ray Diffraction (XRD).