Geometrical roughness analysis of cement paste surfaces using coherence scanning interferometry and confocal microscopy

In this paper, geometrical roughness numbers named RNx, RNy and RNS are formulated as a possible analytical tool for cement-based material surface characterization using coherence scanning interferometry (CSI) and STIL confocal microscopy technique (SCM). Recently, cement paste surface maps have been used to establish a link between surface statistical roughness parameters and the measuring scale (Apedo et al., 2015). The objectives of the present paper are to study how geometrical roughness numbers can be used as a tool to analyze the colonization of cement-based material surfaces by microorganisms as well as to perform other subsequent studies. Observations from a series of images acquired using both techniques (CSI and SCM) on both polished and unpolished samples are described. Using a new method named “window resizing”, the results from CSI are compared with those from SCM. It appears that the surface available for colonization (convolution) is smaller than the surface developed by the measuring tool (sampling). The new method also allows the identification of the fractal regions and the associated fractal dimensions of both polished and unpolished cement pastes.