Investigation of the mechanical properties and the influence of micro-structural characteristics of aggregates using micro-indentation and Weibull analysis

Micro-indentation experiments were performed to study the correlation, both qualitatively and quantitatively, between microstructural characteristics and mechanical properties of three types of aggregates, including basaltic crushed rock, vesicular volcanic rock composed of pumice and recycled concrete aggregates. Emphasis was placed on the measurements of micro-hardness and modulus, and the influence of number of loading cycles. Despite the highly vesicular structure leading to edge chipping during indentation, pumice showed lower variability in indentation hardness and modulus values compared to basalt and recycled concrete aggregate. The number of indentation cycles had different influence on the crystalline structured recycled concrete aggregate and basalt compared to the amorphous structured pumice in terms of hardness and modulus values. Weibull statistics was used to support the important influence of the microstructural and textural characteristics of the aggregates on the bulk properties of the specimens, and different statistical parameters were introduced to characterise the aggregates.