Author(s)

A.J. KLEMM, P. SANJEEVAN & K. ROZNIAKOWSKI

Abstract

The paper is focused on the assessment of laser-treated cementitious surfaces. It forms part of the larger study on laser cleaning process and its effect on modification of geometrical microstructure of cementitious composites. The great variation in absorptivity of highly developed surfaces of cementitious materials results in substantial differences in their responses to laser irradiation. Even though lasers can be successfully used to remove dirt from mortar surfaces, there are always some residual surface alterations associated with the removal of mortar, formation of cracks and glazing (melted mortar). Comprehensive understanding of surface processes resulting from laser interaction with substrate is essential in further industrial commercialisation of the technology. In order to address the problem a wide range of laser-treated samples with different internal microstructures, surface roughness and moisture content were studied. The characteristic features of all laser-cleaned areas included removal of mortar, formation of cracks and glassy patches. Systematic analysis of surface modifications resulting from laser cleaning confirmed a strong relationship between initial roughness of surfaces and their end conditions. An increase in initial surface roughness leads to more pronounced alterations in roughness and reduced tendency towards crack formation.

Keywords

Cementitious surfaces, crack propagation, laser cleaning, porosity, surface roughness