I rebuilt mine using 3:1 cement to sharp sand mixed to semi dry mix.
After two years... one has a slight hairline crack, but this could have been avoided if I done it in two/three thinner applications... something to tweak in summer!
For large areas I made a plywood shuttering arrangement then filled with the mixture and floated with a trowel, it's slow to dry compared to filler, but quite a lot cheaper.
You can also include some brick mesh in sections if you need to make it a bit stronger.
After two years... one has a slight hairline crack, but this could have been avoided if I done it in two/three thinner applications... something to tweak in summer!
For large areas I made a plywood shuttering arrangement then filled with the mixture and floated with a trowel, it's slow to dry compared to filler, but quite a lot cheaper.
You can also include some brick mesh in sections if you need to make it a bit stronger.