A contribution to debate on surface roughness of clay brick powder generated using varying milling treatments

Abstract

Recently, the correlation between surface roughness and fineness of materials including pozzolans has been subjected to too much debate in literature. Exploiting the surface roughness of pozzolans has been proven to be significant for cement-based composites. Although research works have been conducted to assess the effects of milling treatments on surface roughness of pozzolans, limited dedicated studies have explored the use of multi-scale characterisation methods for analysing this complex parameter. In this research, an economic and novel technique was employed to characterise the surface roughness of clay brick powder (CBP) subjected to varying milling treatments of various sample masses. The main aim of this research was to investigate the correlations between fineness levels of CBP and surface roughness parameters. Characterisation of CBP generated from ball milling was performed using scanning electron microscopy (SEM) and Gwyddion. There was significant effort employed during the search for significant trends between roughness parameters and grinding clay bricks using different specimen masses, sadly without success. The results of amplitude roughness parameters, fast Fourier transformations, autocorrelation functions and power spectral density functions demonstrated no significant trends for CBP specimens generated under varying specimen masses. Although CBP specimen with highest fineness level seemed to illustrate the lowest roughness characteristics in some cases (i.e. root mean square roughness of 159.182 nm and mean roughness of 115.444 nm), CBP specimen with lowest fineness level did not illustrate the highest surface roughness properties. Through the analyses, it seemed that CBP specimens subjected to different fineness levels could not illustrate significant differences in surface roughness properties and this observation is contrary to some findings in literature. It is believed that the algorithms used for surface roughness characterisation in this research facilitate the understanding of surface roughness properties of CBP specimens subjected to different fineness levels.