Analytical solutions of surface porosity of waste brick powder specimens from different milling conditions: A path towards sustainability

Abstract

Nowadays the replacement of cement with pozzolanic materials is becoming a very hot topic as a result of CO₂ emission challenges during cement production. Pore structures of pozzolanic materials allow understanding of their effects on pore parameters of cement-based composites. In this study, analytical solutions of surface porosity of waste brick powder (WBP) specimens generated from varying milling conditions were constructed using segmentation, watershed, and threshold algorithms. Scanning electron microscopy was combined with simulations of pore structures from Gwyddion leading to multi-scale driven surface porosity solutions. These methods for surface porosity characterisation of pozzolans can be boiled down to calls for sustainable construction. By implementing analytical methods, the porosity properties of WBP subjected to various milling conditions are successfully observed for the first time. Overall, the presented simulations using all the three methods proved that increasing the mass of clay bricks fed in ball mill reduced the fineness levels of WBP and increased the surface porosity values. It was shown that the porosity values from all the three methods ranged from 17% to 51%. The watershed simulations were noticed to underestimate the surface porosity values in comparison with threshold and segmentation simulations. The results on mean pore areas, number of pores, pore densities, pore volumes and mean pore sizes of WBP specimens were quite different from surface porosity results as variations became more evident for all three methods. The results from this research have highlighted that the proposed analytical solutions are fast and efficient in evaluating the overall behaviour of WBP in cement-based composites and represent reference points for engineering researchers involved in studies on supplementary cementitious materials.