A multi-image analysis suitable to characterise structural parameters of mineral and chemical admixtures for sustainable construction

Abstract

The high use of ordinary Portland cement (OPC) has called for the use of mineral and chemical admixtures replacing cement in cement-based composites. In order to ensure the improvement of properties of cement-based composites, sufficient characterisation of mineral and chemical admixtures replacing cement is essential. For mineral and chemical admixtures, successful characterisation of vital structural parameters, like average pore size, pore size distribution, pore density and surface roughness, is essential. In this study, image analysis methodology of scanning electron microscopy (SEM) images was employed as a method to measure such structural parameters. The main focus of this study was on three software packages: ImageJ, Origin Pro and Gwyddion. Extensive image analyses were performed on OPC, gum Arabic (GA), burnt clay powder (BCP) and rice husk ash (RHA). To shed more light on underlying influence of magnification on key structural parameters of mineral and chemical admixtures, the SEM images were subjected to varying magnifications (270× and 600X). Data on crucial structural parameters obtained by image analysis were compared among the established software packages. Based on the findings, it was understood that most structural parameters obtained by image analysis were consistent and within acceptable accuracy. By increasing the magnification of SEM micrographs, apparent decrease in areas of integration of gray value plots for all the materials was observed. The results on surface porosity indicated that increased magnification reduced the porosity of the mineral and chemical admixtures. From fast Fourier transformation (FFT) findings, it was observed that higher magnification (600×) illustrated clear and bright diffraction spots compared to lower magnification (270×). It was further demonstrated that the increase in pore mouths of the specimens is a function of increased magnification. Meanwhile, surface roughness values computed by Gwyddion at increased magnification reduced compared to those at lower magnification. Data presented herein not only provide characteristics of mineral and chemical admixtures but also provide scientific insights in the use of mineral and chemical admixtures for sustainable construction.