The removal of industrial epoxy grout using a high-power diode laser

Abstract

Due to its inherent versatility and advantageous operating characteristics, the high-power diode laser (HPDL) is being recognised as a most appropriate tool for many engineering tasks. This work details the characteristics and feasibility of a technique to remove industrial epoxy grout using a HPDL. The optimum performance was achieved with an O 2 process gas owing to the highly reactive nature of the gas. A minimum power density of approximately 3 W/mm 2 was found to exist. Furthermore, the minimum interaction time, below which there was no removal of epoxy tile grout, was found to be approximately 0.5 s. The maximum theoretical removal rate that may be achieved using the HPDL was calculated as being 65.98 mm 2/s. A microstructural analysis revealed significant differences in the epoxy grout surface structure before and after the HPDL treatment. The surface of the HPDL-treated samples exhibited a collection of grouped particles with pores and gaps, whereas the untreated samples displayed a continuous mono-structured plane surface. Energy dispersive X-ray (EDX) and X-ray diffraction (XRD) analyses revealed changes in the chemical composition of the epoxy grout after the HPDL treatment. In particular, CaO and CO 2 were found in the HPDL-treated samples resulting from decomposition of CaCO 3 (limestone). In addition, SiO 2 that existed in the non-HPDL-treated epoxy grout material was not detected due to the compound vitrifying. A thermogravimetric and differential thermal analysis (TG–DTA) identified a sequence of thermal history for the epoxy grout which therefore, allowed the prediction of the reactions that occur in the epoxy grout due to HPDL interaction.