Concrete Tunnel Portal Paint suggestions

I suppose I would prefer gray, but a bit darker than they usually are when new. Maybe also slightly weathered. 

I use rustolium camo kahki for aged concrete. 

Light grey and black the first layers.

Linen color wash.from top to bottom.

Andre.

Start with hobby-acrylic gray (light for new concrete, dark for old).  Then overspray lightly with Rustoleum Desert Bisque.

Thanks, will gather colors and give it a go. Doing a few on another layout so will be able to try all your methods and colors.

I agree with grey.

I like the gray, but be sure to weather it. I find the weathering adds nice texture to the finish rather than a fresh painted look

I like Rustoleum camo khaki or desert bisque with chalk weathering. Go in to a HD and  compare the can colors to the concrete floor. I also weather with some orange /yellow artists chalk as some weathered concrete finishes display shades of orange yellow  to my eyes. Folks that have seen my concrete seem to really like the coloration.

All personal choice.

Went with your suggestion based on faith, the Home Depot floor was a bewildering shade which they did not seem to have even a close match in stock.

I've been using the Model Tech concrete color. As I noted on my post yesterday, the jar's threads are the same as the Badger jar adapter. You can air brush directly from the bottle with no thinning. Dries fast as a matte finish.

That is a nice feature.