The two components of wet weather friction on runways are skid resistance and macrotexture. This runway lacked macrotexture because the grooving was not yet done, which would have increased the risk of aquaplaning when there was water on the runway. But it may also have lacked wet skid resistance.
In some cases of new asphalt surfacings, but not all, the wet skid resistance may be unexpectedly low for a short time (Low here is defined as the skid resistance level which would trigger an investigation for higher-risk sites).
Some research has confirmed the suggestion that these “early life” phenomena can be attributed to the presence of a film of binder that can adhere to the surface of the aggregate for a significant period of time (until the traffic wears it off).
The binder film appears to have several effects, of which the key one for this wet runway is:
(i) It prevents the microtexture on the aggregate particles making contact with the tyre, resulting in lower wet friction at higher speeds than would normally be expected.
The fact that the runway was wet for several days leads me to also speculate about some slight emulsification occurring of the bitumen. Depending on the properties of the bitumen, this could also lead to either more of this binder film or even another film on the surface. Accentuating the problem. It would be nice to see some [accurate] wet weather skid resistance measurement results on the runway.