Micro-scale alterations of cementitious surfaces subjected to laser process and their impact on long term durability

The paper presents part of the larger study on laser cleaning process. A special emphasis is placed on the modification of geometrical microstructure and chemical composition of cementitious composites resulting from cleaning process. A wide range of samples characterised with different internal microstructures, surface roughness, and moisture content were subjected to laser cleaning process, and a subsequent assessment. Removal of mortar, cracks and glassy patches were the characteristic features of all laser-cleaned areas. Cracks of wider openings may also form as a consequence of the expansion of water/air inside pores, predominantly smoother/denser mortars. The experimental results prove that the laser cleaning process leads to an increase of Si element concentration and/or decrease in Ca concentration. The observed alterations should be associated with changes in the relative distribution of melted cement paste and aggregate and therefore relative elemental abundance in the near-surface layer.