An examination was undertaken on the alkali-silica reaction (ASR) in alkali-activated slag (AAS) mixtures in comparison with ordinary portland cement (OPC) mortars and concretes. The ASR expansion in AAS mortars and concretes with different alkali contents (5%, 6%, 7%, and 8%) was examined. Changes in mechanical properties (compressive strength, tensile strength, and flexural strength) resulting from ASR expansion were evaluated. A correlation was sought between the changes in the mechanical properties of mixtures caused by ASR and ASR expansion. The test results revealed that the ASR expansion of all AAS mixtures was less than that of OPC mixtures. The expansion of AAS mixtures was below the threshold value established by the standard specifications. Additionally, it was possible to use mechanical properties to assess the occurrence of ASR due to the significant drop in these parameters caused by ASR
