Quantitative study on surface porosity and roughness parameters of mineral and organic admixtures based on multi-scale characterisation techniques

Abstract

Studying surface porosity and surface roughness of mineral and organic admixtures is vital in cement-based applications as these characteristics play a significant role in the behaviour of cement-based composites. Aiming to enhance the characteristics of coconut shell ash (CSA), gum Arabic (GA), cassava starch (CS), rice husk ash (RHA) and burnt clay powder (BCP) including their influence on cement-based composites, the surface porosity and surface roughness characteristics were comprehensively explored using scanning electron microscopy (SEM) under scale of 100 µm and Gwyddion. The surface morphological measurements, surface porosity and surface roughness of the specimens were respectively assessed using parameters such as skewness (Rsk), Kurtosis coefficient (Rku), roughness average (Ra), root mean square roughness (Rq), waviness average (Wa), root mean square waviness (Wq) and plane porosity. The roughness average values were noticed to range from 19 nm to 77 nm whilst the root mean square roughness values were found to vary from 27 nm to 107 nm. The waviness average and root mean square waviness values of specimens ranged from 26–132 nm and 34–157 nm respectively. The skewness values were observed to range from −0.18–0.72 while Kurtosis coefficient values ranged from 3 to 12. The comparisons in plane porosity quantification findings obtained using the implemented algorithms illustrated that the plane porosity values from threshold method were higher than those from segmentation method. The findings from this study extend characterisation of mineral and organic admixtures and subsequently guide management practices of waste materials through utilisation of mineral and organic admixtures in cement-based composites.