This test method covers determination of material nonlinearity in concrete laboratory specimens prepared in a manner and subjected to conditions of accelerated alkali-reactivity of aggregate. It is assumed that the nonlinearity due to elastic hysteresis is a dominant mechanism for the material nonlinearity in concrete specimens with alkali–silica reaction (ASR) damage and that this nonlinearity is directly proportional to the ASR damage occurring in the specimens. This method may not be necessarily applicable to other forms of damage. This standard was formerly designated as provisional standard TP 109.