By analysing samples of concrete taken from the property by various methods the presence of substances known to cause problems can be confirmed. The analysis process is as follows;
Stage One, involves detailed examination of core samples under a low power microscope. To a trained petrographer, identification of the aggregate type can be made from this inspection and, in the majority of cases, a classification for the concrete can be determined. It must be stressed that approximately 75% of properties tested will pass the Stage One analysis, receiving a Group A classification.
Stage Two analysis involves the core sample being cut into wafer-thin segments for a further examination under a high power microscope and possibly subjected to a range of ancillary analytical techniques. Stage Two analysis is not included in the initial Stage 1 cost and is only carried out if a Stage 1 test is inconclusive.
Stage Three involves the sample being subjected to an accelerated weathering test under environmentally controlled conditions in an attempt to activate a reaction between the aggregate and cement binder. This test takes place over several months.