Paper Review

Paper Review

Nguyen Phi Long [a], Hiroyuki Daido, Tomonori Yamada, and Akihiko Nishimura, Noboru Hasegawa, Tetsuya Kawachi

Laser Technology Institute, Japan Atomic Energy Agency, 65-20 Kizaki, Tsuruga, Fukui 914-8585, Japan

Naraha Remote Technology Development Center, Japan Atomic Energy Agency, 1-22 Aza-Nakamaru, Oaza-Yamadaoka, Naraha, Futaba, Fukushima 979-0513, Japan

Kansai Photon Science Institute, National Institutes for Quantum and Radiological Science and Technology, 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215, Japan

Journal of Laser Applications IF: 1.8 [Published: 2017]

This paper investigates the mechanisms and optimal conditions for drilling and cutting concrete using a high-power quasicontinuous wave (QCW) fiber laser without an assist gas. The study reveals that material removal is primarily driven by vaporization and melt expulsion. When the laser heats the concrete, it creates a molten pool. Recoil pressure from vaporization, combined with the expansion and breakup of trapped gas bubbles, vigorously expels this molten material even after the laser pulse ends.

A key finding is that upward laser irradiation significantly outperforms the conventional downward approach. In upward processing, gravity assists in removing larger molten droplets from the hole, increasing penetration depth by 20% to 30%. Furthermore, the study highlights how varying laser parameters—such as peak power, repetition rate, and overlapping ratio (optimal at 40-50%)—can be tuned to maximize cutting efficiency and prevent clogged kerfs. Notably, the heat-affected zone (HAZ) is kept strictly under 3 mm, demonstrating the QCW laser's high thermal precision for concrete processing.

Yi Jian [a], Xingwang Bai [a*], Penglei Jie [a], Lingfeng Luo [a], Min Mao [a], Changjun Qiu [a], Zebin Zhu [b], Yuguo Kang [b]

[a] School of Mechanical Engineering, University of South China, Hengyang, Hunan, 421001, PR China

[b] Dadi Special Exploration Team of National Mine Emergency Rescue, Bei'jing 100040, China

Optics and Laser Technology IF: 5.0 [Published: 2026]

This study investigates the material removal mechanisms and parameter influences in remote laser cutting of concrete without the use of assisted gas, which is a critical requirement for long-distance rescue and facility demolition. Due to the absence of auxiliary gas to blow away molten slag, the material removal rate in long-distance operations remains relatively low. The research identifies that the primary methods of material removal are splattering, slag dripping, and crack propagation. Splattering is caused by instantaneous vaporization from localized high temperatures, while slag dripping results from gravitational drainage of molten glass through the kerf. Furthermore, crack propagation is induced when internal vapor pressure exceeds the tensile strength of the concrete, leading to structural failure. Experimental results demonstrate that for a 50 mm-thick concrete sample at a distance of 14 m, the cutting speed can reach $1~mm/s$ at 2 kW and $2~mm/s$ at 4 kW. It was found that choosing a positive defocusing (+2 m) configuration significantly enhances performance by enlarging the kerf width and promoting better slag dripping. Additionally, the study proposes a reciprocating cutting method which involves multiple repeated passes; this approach was shown to increase the material removal rate by 11.3% compared to single-pass cutting by re-cutting and ejecting solidified slag deposits. These findings provide a vital parameter basis for improving the efficiency and quality of remote laser cutting in complex emergency and decommissioning scenarios.