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 surfaces 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). The reflectivity properties of the CR material from the visible to the near infrared wavelengths (500–1100 nm), as well as their behaviour under high temperatures have been examined with a normal incidence reflectance spectrometer. 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 combustion process and the resulting coating removal. The ash particles produced during the process were collected and examined. Safety aspects of the process as well as the removal quality were assessed and discussed. The results were also compared with normalised data from Nd:YAG, CO2 and Arc Lamp processing of the same material.