Removal of chlorinated rubber coatings from concrete surfaces using a 120-W high power diode laser

We report the process characteristics for removing white chlorinated rubber (CR) coatings, pigmented with titanium white (TiO2), from concrete surface s utilising a 120-W continuous wave (cw) diode laser in the near infrared. Some 0.3 mm thick coating layers were removed utilising oxygen process gas flow. Examination of the effectiveness of paint removal was facilitated by the use of optical microscopy and energy dispersive X-ray analysis (EDX). T he reflectivity properties of the CR material from the visible to the near infrared wavelengths (500-1100 nm), as well as their behaviour under high t emperatures have been examined with a normal incidence reflectance spectrom eter. Even though the reflection coefficient of white CR at 810 nm is very high, the drop in reflectivity after a brief period of irradiation through thermal damage, may explain the initiation and continuation of the combusti on process and the resulting coating removal. The ash particles produced du ring the process were collected and examined. Safety aspects of the process as well as the removal quality were assessed and discussed. The results we re also compared with normalised data from Nd:YAG, CO2 and Are Lamp process ing of the same material. (C) 2001 Elsevier Science B.V. All rights reserve d.