Comparative analysis of test methods for identifying alkali–silica reactivity in concrete aggregates

The alkali–silica reaction (ASR) poses a serious threat to the durability and structural integrity of concrete infrastructure worldwide. This study critically evaluates the effectiveness of ASTM C227 and ASTM C1260 standards in determining the ASR potential of five locally sourced aggregate samples, including Kuchlack, Jabal-e-Noor, Hanna, Speyzaind, and Bolan. Physical and chemical characterization, alongside petrographic analysis, were conducted to identify reactive components within the aggregates. Mortar bar expansion tests were performed under both ASTM protocols to assess elongation and determine reactivity. The findings strongly affirm that ASTM C1260 is more effective than ASTM C227 in identifying potentially deleterious aggregates. While all samples remained within acceptable expansion limits under ASTM C227, the Sepyzaind aggregate demonstrated excessive expansion under ASTM C1260, confirming its slow-reactive nature. This was further verified by a marked reduction in compressive strength (16 %) and modulus of rupture (9.3 %) for Sepyzaind aggregate under ASTM C1260 conditions. The remaining four aggregates consistently tested non-reactive across all parameters. These results emphasize the superior diagnostic capability of ASTM C1260 and underscore the necessity for rigorous ASR evaluation, especially in regions that depend on local aggregate sources. This study offers critical insights for engineers, researchers, and policymakers committed to enhancing the long-term performance and safety of concrete structures.