Abstract

This present work describes the differences in the characteristics of glazes generated on the ordinary
Portland cement (OPC) surface of concrete by means of CO2 and high power diode laser (HPDL)
radiation. The value of such an investigation would be to facilitate the hitherto impossible task of
generating a durable and long-lasting surface seal on the concrete, thereby extending the life and
applications base of the concrete. The basic process phenomena are investigated and the laser effects
in terms of glaze morphology, composition, phase and microstructure are presented. Also, the
resultant heat affects are analysed and described. The glaze generated after HPDL interaction was
found be fully amorphous in nature, whilst the glaze generated after CO2 laser interaction was seen to
be of a semi-amorphous structure, with sizeable areas, randomly located within the glaze, displayed a
somewhat regular columnar structure. This is proposed to be due to the differing solidification rates
occasioned by each laser after treatment as a result of differences in the beam absorption lengths.