Distance 0km [total: minimalist 23.5km: Barefoot 27km]
Here is the information on the sort of temperatures to expect on various running surfaces on a warm day.
Much to my surprise, the surface which I expected to be the hottest wasn't.
With an ambient temperature of 37C when the measurements were taken I found the average temperatures to be in the following order.
Bitumen road was 41.9C
Concrete pavement 44.0C
Brick paving 48.6C
Bitumen path Black 49.3C
The theory I have on why the brick paving is hotter than the bitumen is that bitumen is a thin layer that distributes heat more evenly and quickly.
The brick retains the heat and can only dissipate it into the air above, the bricks are much thicker than bitumen.
So, if you are running barefoot in warmer weather stay on the bitumen rather than brick pavements.