On the quantitative analysis of surface roughness properties of teff straw ash-based geopolymer mortar using fractal theory

Geopolymer mortars have traditionally attracted the attention of engineers due to their significant role in accomplishing sustainable construction. While most mechanical properties of geopolymer mortars are straightforward to compute, their surface properties are, by comparison, more challenging to estimate. The quantitative evaluation of surface characteristics of teff straw ash (TSA)-based mortar using fractal theory based on scanning electron microscopy (SEM), has also received limited attention in literature. In this study, the fractal characteristics of TSA geopolymer mortars are obtained using partitioning, power spectrum, triangulation and cube counting algorithms. The findings illustrate that the fractal dimensions from the four algorithms vary appreciably from 2.53 to 2.89, suggesting that the surface characteristics of TSA geopolymer mortars are not very smooth. The overall increment in fractal dimension behaviour for heat-cured specimens compared with ambient-cured specimens becomes predictable for the power spectrum algorithm only. On the other hand, the influence of high temperatures on fractal dimension values of TSA geopolymer mortars is not significant for partitioning, triangulation and cube counting algorithms. In addition, the fractal dimension reductions are captured as the compressive strength increases for cube counting and triangulation algorithms. For power spectrum and partitioning algorithms, fractal dimension is not considerably impacted by the compressive strength of TSA geopolymer mortar. In all cases, the quantitative methods of fractal dimensions are a fruitful path in determining the fractal properties of solids and can be tailored to meet the specific surface properties’ requirements desired in various applications.