Nondestructive investigations of expansion gap concrete roughness

•The analisys of poor layouts in application of sealing material to concrete surface.•The influence of concrete surface treatment on material penetration into pores.•Improved adhesion of concrete and materials used to fill expansion gaps.•Results of different manual and mechanical preparation in bond coat. This paper presents the results of non-destructive investigations of concrete roughness in expansion gaps in reinforced concrete structures. The goal of this paper is to contribute to surface roughness measurement techniques. Concrete specimens with differently prepared surfaces: 1) not rubbed down, 2) manually cleaned and 3) mechanically cleaned were examined. The spatial geometric structure of the specimen surfaces was investigated using a scanning optical profilometer. Surface geometry, profile and roughness were measured. Then surface features were analysed and presented in the form of histograms, Abbott-Firestone material ratio curves and surface micro asperity profiles. Moreover, area-related surface topography parameters, i.e. height, frequency and hybrid parameters as well as functions and associated parameters, were determined. Then morphometric measurements, geometric profile and roughness measurements as well as analyses of the surface undulations and the spatial locations of the parameters were carried out. The results obtained for the mechanically prepared surfaces were found to be the best. The results were compared and conclusions important for building practice were drawn.