I call them heat sponges. I have their boxes on an outside ooarch with windows. Kind of like a Florida room that closes but not nice! Its closed to our house . Anyway when its 97f outside and hotter on the porch cause of little air flow she's sleeping out there!
When I started working commercial construction in the late 80's,they were pretty new.Never heard of them until on one of my first jobs.They've always cut their own threads,work great in soft-medium masonry or concrete - dont think they'd work in granite,super dense precast concrete or harder limestone though.Most times I see soft plastic expansion plugs w/screws,wedge/sleeve anchors or epoxy used in those situations.
Around here for temp concrete formwork that doesn't support a lot of weight (nothing overhead for example) instead of using more expensive tapcons that just get lost in the sand or mud for anchoring sill plates or other things most jobs they drill a hole with that 3/16" carbide tapcon bit & drive a 16 doublehead nail w/ small piece of ironworker's rebar tie wire in that hole..Fits so tight even my 28oz Estwing hammer cant pull most of them.Small crowbar works wonders though.........
We have been using plastic anchors and screws for years. Drill a 1/4 hole in block or concrete, tap in the plastic anchor, and run a small black screw in. Make sure your holes are level/plumb when laying it out. Not much wiggle room. Quick easy cheap. Something like these http://www.goodmart.com/products/ideal-90-042-red-flange-type-plastic-anchors.htm
Tapcons do work good in concrete but are way overkill to hang tin signs. And they are about 60 cents a piece. Plastic anchors are about $6 per 100.
Signs that are large or have holes already in them I would use plastic anchors/screws. Not a tapcon application here. Tapcons are great for the right application, but not a match for this. Signs that have holes, you can place on the wall and trace the hole pattern for perfect placement. Others would need to be drilled for screws. Wouldn't do that. 3m double sided tape. Make sure it is the thicker stuff too. The block is porous so the face is not going to be flush for thinner tapes to make good contact.
