10:15 〜 10:30
▲ [14a-2F-4] Evaluation of pulsed laser irradiation on concrete using a QCW laser system
キーワード：Laser drilling,Concrete,Melt ejection
Laser irradiation techniques for removing degraded parts of concrete structure such as tunnel's concrete of railways safely and efficiently is an urgent task, since the significant defects in wall concrete have been detected in the JR West tunnels, Japan. Pulsed laser processing of material is an important part of the laser technical application, which include laser drilling, welding, cutting, etc. Advantages include a non-contact processing, a low heat input into the material, accuracy and consistency. An understanding of mechanisms of ejected molten material and characteristic of hole drilled in laser drilling concrete is necessary to enhance the performance for pulsed laser irradiation on concrete. In this work, the characteristic of hole drilled into concrete and the material removal mechanism corresponding to the temperature of surface concrete during laser drilling were investigated by using high speed camera and thermography. The QCW (Quasi continuous wave) fiber laser system having compact dimensions was used in this experiment, allowing for a maximum peak power of 1.5 kW and average power of 150 W, operating at 1070 nm. Experiments have been performed on two types of concrete sample, such as heavy and real tunnel concrete..
As an experimental results, the melt concrete is removed from the interaction zone both in vapor (laser on) and melt liquid state (laser off). In addition, the penetration depth was achieved on 20 mm thick with peak power of 1600W within 10s. This basic study of pulsed laser drilling provides useful information to control and enhance the performance for laser irradiation on concrete. The QCW laser system is recommended for removing the concrete defect in tunnels due to its compact dimensions and responsive performance.
As an experimental results, the melt concrete is removed from the interaction zone both in vapor (laser on) and melt liquid state (laser off). In addition, the penetration depth was achieved on 20 mm thick with peak power of 1600W within 10s. This basic study of pulsed laser drilling provides useful information to control and enhance the performance for laser irradiation on concrete. The QCW laser system is recommended for removing the concrete defect in tunnels due to its compact dimensions and responsive performance.