Hi @322811,
Thank you for your question and welcome to the Bunnings Workshop community, it is fantastic to have you with us.
The treated pine doesn't look too bad. The section in the first photo appears splintered but doesn't appear rotten. Are there sections that have gone very soft? If you take a screwdriver or a key and stab it into the timber it would pierce the timber easily if it were rotten.
You could remove and replace the splintered sleeper, but it would be tricky because it is held in place with cup head bolts where the nut is hidden underneath the asphalt.
The only way I can see to remove the sleeper, without causing a great deal of damage to the asphalt step, is to cut the head off the bolt using an angle grinder and drive the bolt through the timber. Once it is out, you can replace the timber sleeper with a treated pine sleeper of the same size.
The asphalt also looks to be in fairly good condition, albeit with a few cracks here and there.
You could give the asphalt a good pressure clean and use some Gripset Betta 1L Asphalt Crack Filler to fill the cracks, but outside of this, there's not a lot you can do besides removing and replacing it.
Let me know if there's a particular issue you want assistance with.
Jacob
