Fix old patch on concrete stairs

[Anonymiserad 681858]

Hello,

How do I fix this old repair in my concrete staircase? I was planning to just paint the staircase. But I would like to address these cracks that have appeared in the repair first. Does regular concrete filler work? Or should I chisel everything away and use what?

 

[a_w]

Knock off and cast new. Make sure to water well before casting. It slightly tastes what you use for mortar and depends on how thick you need to cast. But see e.g. Weber EXM 702. Follow the concrete supplier's instructions regarding adhesion and curing. Ensure to get a coarse surface when you chisel away the concrete so that the new concrete adheres. Fun project!