This is a video, from YouTuber OliKills, showing two guys using a thermal lance (Wikipedia), also called a “thermic lance” or “burning bar,” to cut through a lump of concrete. It really gets going about 20 seconds in, and by the end of the video a white-hot stream of molten concrete “lava” is clearly visible running across the pavement.
If you’re a fan of Mythbusters, or you’ve seen……any one of a number of heist movies (like The Score, The Thief, or The Bank Job), you probably already know what a thermal lance is. Mythbusters actually tested the feasibility of using a thermal lance to crack a safe in Episode 59: Crimes and MythDemeanors II, and concluded that while, yes, you can use one to cut open a heavy safe, the heat generated in the process will likely destroy the contents. (Of course, if it’s full of precious metals, it may not matter too much if they get a bit melty. In fact it might be desirable. You know, like in Cryptonomicon?)
Image courtesy MachineDesign.com.
Anyway, the tool itself is beautifully simple: a long iron rod packed with smaller iron, aluminum, or magnesium rods. Oxygen is fed through the tube from the “safe” end, and it’s ignited at the cutting end with an oxyacetylene torch. The cutting operation consumes the lance itself. Supposedly the business end can reach 4,400 C (8,000 F).
Theodore Gray has, somewhat famously, used a kind of “thermal lance” fueled by bacon to cut through steel.