Severity investigation

From the confirmation inspection and its subsequent test results the presence of AAR has either been confirmed or eliminated. Assuming the first outcome, the next step is to investigate the severity of the situation, see Figure 23. One should keep in mind that it is possible that some evidence of AAR may be found in concrete where siliceous material forms part or all of the aggregates, whether or not the concrete has cracked or expanded as a consequence of AAR. Concrete can have ‘sub-clinical’ AAR where isolated areas of reaction may be identified under the microscope, even where it has not caused significant expansion or cracking of the structure. Many concretes have very localised areas showing ASR gel and reactive particles which are not sufficient to produce significant cracking or damage to the structure. Diagnosis of this ‘Sub clinical AAR’ as “AAR” has frequently caused undue concern and overreaction by engineers and client organisations