38C is only 100F. Asphalt gets tacky when its in 90+ degree heat for long, but its still safe to drive on. Are planes just so heavy that they sink into the runway? Or are runways made of softer stuff?
Possibly different mixes depending on the environment.
I think you're right. Apparently, tarmac is not only the name of the area of an airport, but also the name of a material, and tarmac is different from asphalt.