Depends on the airfield, and when. For example, those airfields in the UK which were 'for the duration', normally had matting at dispersals, and as a runway, whereas those airfields which were already in existence, but required additional hard dispersals, would normally utilise PSP for these. There were, of course, variations, with a mix of both materials, or none at all.
On the Continent, when the first air strips were made, Marsden Matting, or Sommerfield Track, would be laid as a general rule, although if the surface was suitable, this might only be used for the runway, if at all. These materials were used initially as they were quicker and easier to transport and lay, compared to PSP, for airfields which might only be used for a number of days, or a few weeks. Later, as more 'semi-permanent' bases were established, and especially as wetter weather approached, PSP was used.
If you know which airfield is being depicted, I might be able to let you know what, if anything, was used - and having to paint Marsden or Sommerfield will be a lot easier than depicting PSP !