In the U.S. at least, it's very unusual to see a 60-ton truck on the highway - most are limited to 40 tons, with special permitting needed for heavier loads. Australia's a whole different story, but their road trains have many more brakes to distribute the energy across.
And that means it's going to take a while as that heat dissipates - the brakes will literally melt if you try to brute-force a shorter braking distance, for example by increasing braking system pressure.
Increasing the pressure will lock the wheels up (not taking ABS into account), at which point the rotors/drums aren't absorbing any more heat and stopping distance is determined by the friction of the sliding tires. That said, truck brakes are *big*, and are quite capable of handling a 50 mph panic stop without damage to the brakes.