Utilizing alkali-activated slag (AAS) as a cement replacement material has significantly reduced the cement industry’s overall carbon footprint while enhancing the potential for the improved technical performance of concrete. However, using activators with high alkalinity has the potential to result in Alkali-Silica Reaction (ASR) in concrete containing reactive aggregates, which restricts its application in commercial settings. The occurrence of ASR can cause changes to the mechanical properties of concrete due to the development of delayed cracks. Therefore, designing a concrete structure necessitates determining the extent to which concrete is susceptible to ASR. In this paper, mechanical strength tests were conducted to assess the effect of ASR on the properties of concrete. In addition, electrical resistivity measurement was utilized to investigate the occurrence of ASR in concrete mixtures containing AAS and reactive aggregates. The correlation between ASR expansion and electrical resistivity was examined. Reference mixture and AAS concrete mixtures with varying alkali/slag (Al/slag) ratios were prepared for this purpose. The results showed a good correlation between the electrical resistivity data and the expansion caused by ASR.