ASR-Related Distress in Floor Finishes

Alkali-silica reaction (ASR) is a common distress mechanism associated with certain aggregates in portland cement concrete. Small amounts of potentially ASR-reactive particles are common in many aggregates. These particles may or may not be destructive to the concrete as a whole, but ASR can cause distress to sensitive finishes even when present in small quantities in the near surface. Several cases of blistering of flooring related to ASR were investigated in Colorado and nearby states where the reactive aggregate contents were less than industry limits. The investigations revealed that the blistering of the flooring was caused by a relatively small amount of reactive particles located in the near surface concrete. However, there have been investigations where reactive particles were present in small quantities, but not causing distress. In this article, practicing forensic engineering professionals will gain a better understanding for the potential for this form of distress; how to properly identify the potential for ASR to cause distress of sensitive finishing materials through appropriate detailed field and laboratory evaluations; and potential implications if found.