Gap between wall and driveway paving - Advice on filling the gap!

[Psy]

Hello all,
our driveway is those ~3ftx4ft concrete paving slabs you see on drives all over the uk. Where the slabs meet the bay window there are triangular gaps between the wall and the slabs that have been filled in with what looks to be concrete. It's all fairly well sheltered by the roof above but a few chunks of cement have cracked and come loose leaving a hole with some cement still inside, some dirt and possibly some soil from underneath showing. This has lead to a damp patch on the inside of the wall that comes and goes with the wet weather. Anyone got advice on how to repair this? current plan is to clean out the damaged area (water and a brush) and then fill back in with a dry 4:1 sand:cement mix and wait for it to cure. Main queries with this are: do I need a plasticiser to prevent it cracking again (if so any advice on which/how much to use?), will the new cure to the old ok or should I remove as much of the existing cement as possible and ensure a good sand foundation?
Any advice much appreciated.
thanks,

[seanandruby]

Photo's would be good so we can view it and give better advice.

[Psy]

Hi sorry, only just worked out how to do this... let me know if it doesn't work and I'll try something different!
https://imgur.com/a/h3Yt2

[seanandruby]

Think i'd be inclined to bin the lot and start agaon, looks dated and not if it's laid on soil. Also repoint the brickwork. Is the concrete breaching the D P C?

[jwill]

Looks to be 9" below dpc? Do you this these are perforated engineering without a dpc? Still would it wick that much up?!

Be inclined to point and seal brickwork as first port of call

[Psy]

Yeah seemed to be well below the dpc and can't see anything that would bridge it... The pointing is pretty shoddy, looks like someone hasnt properly scraped out the old stuff before putting new on top so the new is flaking out. Although I recently heard you shouldn't scrape out the old stuff as it damages the brick and can widen the gap but that seems like bs to me?
Still, I couldn't see anywhere obvious that the pointing is very bad and this area is fairly sheltered by the roof so the floor barely gets wet nevermind the wall.
The concrete next to the wall seems to be the only localised thing that I can imagine making that much damp? But again it's below the dpc so shouldn't wick up through that! Unless it's damaged/broken.
As you can see I'm quite confused!

[Tony McC]

I don't think that bit of failed concrete is the cause of the problem. There's summat else going on that only a site investigatiuon would reveal.

[Psy]

I was worried that might be the case. Won't their response just be that we should add a new DPC and see if that solves it?