Concrete is the material of choice for innumerable bridges, roads, buildings and superstructures. Though it is incredibly versatile and deceivingly simple concrete is susceptible to deterioration and deformation if not designed, mixed, poured, cured, and reinforced properly. In concrete structures, both new and old, scaling, spalling, cracking, low strength, and delamination are just a few of the deterioration artefacts that give owners, project managers and contractors cause for concern.
Concrete petrography is utilized to understand what is occurring within the concrete to account for the type of deterioration observed.
What exactly can concrete petrography do? Petrographers evaluate concrete, in bulk and in thin-section, using reflected light, transmitted light and occasionally x-ray diffractometer and scanning electron microscopes to collect an incredibly large amount of data that includes the following:
- classification of coarse and fine aggregate;
- identification of portland cement and supplementary cementitious materials (including fly ash, slag, and silica fume);
- mix design verification including estimates of the water-cement ratio;
- evaluation of consolidation and mixing;
- investigate for causes of low strength;
- identify causes of surface scaling/spalling (including improper finishing);
- determine the depth of carbonation and depth of hydrophobic materials;
- classification of secondary deposits/mineralisations;
- evaluate cracking and microcracking including thermal shrinkage cracking, early-age shrinkage cracking, and plastic shrinkage cracking;
- evaluate concrete for thermal damage from a fire event; and
- identification of durability mechanisms including alkali-silica reaction (ASR), delayed ettringite formation (DEF), chemical attack, rebar corrosion, freeze-thaw damage, and more.
Microanalysis Australia offers a range of petrographic services that can be utilized on concrete (cores or fragments) of any age and is not specific to either new or old construction. They are also available for the evaluation other building materials such as mortar/render, stucco, aggregate, flooring, and riprap.
For more information on how we can assist you with your concrete petrography please contact our Specialist Geologist/Petrographer Dan Cukierski or Rick Hughes on +61 8 9472 4880.
