ASR models for siliceous aggregates with different texture and structure characteristics

The ASR features of silica glass, zeolitic perlite and siliceous gravel were examined by optical microscope and SEM. Based on the results and some published research on ASR of slow expansive aggregates, a hypothesis concerning ASR models for siliceous aggregates with different texture and structure characteristics was proposed. It suggests that (a) the ASR process and the expansion behavior are different for aggregates with different textures and structures; (b) the classical ASR model is only suitable for interpreting the ASR behavior of homogenous amorphous silica; and (c) for slow expansive poly-mineral aggregates, the distribution of the constituent or physical structure has a strong influence on its ASR process and the expansion behavior, in addition to the type and amount of reactive constituents in aggregates. The primary differences displayed in the ASR process and expansion behavior for aggregates with different texture and structure characteristics lie in the differences in the site and the restraint condition for the ASR expansion.