The Accelerated Mortar Bar test (AMBT) is rapid, reproducible, and perhaps the most widely used technique for examining the potential alkali-silica reactivity of aggregates. Unfortunately, this test is often unreliable as it may identify non-reactive aggregate as reactive and vice versa. With the aim of improving the accuracy of AMBT, two modifications to the current procedure were evaluated: 1) the maturity of mortar bars prior to alkali hydroxide exposure and 2) reduction of the storage temperature. The original and modified versions were performed on six aggregates with alkali-silica reactive (ASR) components, and their expansions and ASR classifications were compared. Results show that increasing the maturity had no significant impact on expansions. However, modifying the storage temperature to 60˚C and extending the period of testing to 28 days can be very effective in terms of more reliably identifying the existing falsely identified aggregates.

The Accelerated Mortar Bar test (AMBT) is rapid, reproducible, and perhaps the most widely used technique for examining the potential alkali-silica reactivity of aggregates. Unfortunately, this test is often unreliable as it may identify non-reactive aggregate as reactive and vice versa. With the aim of improving the accuracy of AMBT, two modifications to the current procedure were evaluated: 1) the maturity of mortar bars prior to alkali hydroxide exposure and 2) reduction of the storage temperature. The original and modified versions were performed on six aggregates with alkali-silica reactive (ASR) components, and their expansions and ASR classifications were compared. Results show that increasing the maturity had no significant impact on expansions. However, modifying the storage temperature to 60˚C and extending the period of testing to 28 days can be very effective in terms of more reliably identifying the existing falsely identified aggregates.