Influence of aggregate size and aggregate size grading on ASR expansion

The influences of aggregate size and aggregate size grading on ASR expansio n in the Chinese autoclave test were studied. The result shows that the eff ect of the addition of coarse aggregate on the expansion of mortar is compl ex. It may be inhibiting expansion, may have no effect, or may be promoting expansion. Moreover, its effect will change with age. By theoretic analysi s of micromechanics, it is shown that the effect of coarse aggregate on the expansion of mortar depends on the relation between the free expansion of coarse aggregate epsilon(a) and mortar epsilon(s). From the results of expe rimental and theoretic analyses, the authors suggest that for the evaluatio n of the alkali-reactivity of aggregate, single-size aggregate grading migh t be more reasonable. (C) 1999 Elsevier Science Ltd. All rights reserved.