The Following gallery of photos are provided to show examples of the Alkali-Silica Reaction (ASR) which is the reaction between the alkalis (sodium and potassium) in Portland Cement and certain siliceous rocks or minerals, such as opaline chert, strained quartz, and acidic volcanic glass, present in some aggregates; the products of the reaction may cause abnormal expansion and cracking in concrete in service. The following photos are various examples of Alkali-Silica Reaction (ASR) in concrete in service.