Representativity of morphological measurements and 2-d shape descriptors on mineral admixtures

Abstract

Using mineral admixtures has been proved to be significant for the production of cement-based composites. Burnt Clay Powder (BCP), Rice Husk Ash (RHA), Coconut Shell Ash (CSA) and Gum Arabic (GA) can be used as cement substitutes in cement-based composites whilst Cassava Starch (CS) can be used as an admixture in cement-based composites. Understanding shape parameters, microstructure and morphology of mineral admixtures and thus utilising them more efficiently for practical applications is critically required. Although research has been conducted to characterise mineral admixtures, limited studies have documented the combined Scanning Electron Microscopy (SEM) and image analysis. Thanks to image analysis-based methodology, it was possible to establish circularity (Circ), roundness (RD), solidity (SLD), axial ratio (AR), surface porosity (SP) and surface roughness (SR) of pozzolans and admixtures. This involved usage of SEM images of mineral admixtures to establish shape descriptors, porosity and surface roughness of mineral admixtures using image-based analysis and assessing the correlation and interdependence among the parameters. The mineral admixtures in this study were characterised by average values of solidity, roundness, circularity and axial ratio of greater than 0.7. Evaluation of correlation between roundness and circularity illustrated weak R2 values ranging from 0.30 to 0.40 for all mineral admixtures. The axial ratio also weakly correlated with solidity with a wider range of R2 values from 0.27 to 0.45. Importantly, the relationships were noticed to be significant in the interpretation of morphology and shape data.

Keywords

• Shape descriptors
• Surface porosity
• Scanning electron microscopy
• Mineral admixtures
• Morphology
• Image analysis