[Malcolm]

I need to fill small holes in concrete block from fastener holes. What should I use? Would caulk work? I need something that can be paintable in 24 hours.

 

[de-nagorg]

I would put a little construction adhesive in each hole, then smooth it up with a plastic putty knife, or an old credit card.

Let it set, and primer over it, then a finish coat.



ED

 

[Gymschu]

Caulk would work although I would favor caulk made for masonry. De-nagorg's process would work just fine. Maybe look into a urethane caulk such as watertite. It expands rather than contracts like regular caulks do.