How do I go about fixing this hearth?

[Jamhan]

As per title, I have an old fireplace hearth I would like to repair before painting it.
I assume wall filler can't be used in this instance?
It's 10mm deep, but a wide area. It will be walked on, but there is no actual fire.

My level of DIY is beginner, so if there are any ready-mix products I can buy, that would be better than buying and mixing up stuff myself.

 

[bobasd]

OP,
you've got damp problems under that hearth - there's been previous repairs and the nail heads are rusting out.
the fender wall soil infill and the hearth trimming are the problems.
the site you posted on Tue at 12:45 shows what can happen with damp.

its best if you remove the hearth and lift some boards and then pic and post whats been exposed.

if you simply want to repair the skim of sand and cement then use, say a small tub of Cementone repair mortar from any supplier - but first prep the patch with some Pva or similar.
once the hearth mortar skim begins to go it will constantly crack if walked on.

 

[Jamhan]

Thanks @bobasd. How do I go about breaking up the hearth?
Tried breaking with a mallet and some old metal chisels, but they're blunt and I don't seem to have got very far.

I have to also remove an inch thick layer of concrete on a different hearth, so we can tile it, same question applies there. Thank you

 

[bobasd]

i assume that you want to break up the whole hearth, not just the topping layer of mortar, and excavate the soil etc?
it might be that the inset back hearth needs to be also broken out?
you can hire a small/medium breaker with chisels - 110v or 240v.

maybe the other hearth is in a similar condition ref as a cause of rising damp?