May 31, 2016 - I mixed a tiny amount of tan acryllic paint with about a cup of of spackle, then used the resulting mud to finish dirting in the abutments, piers, and tunnel portal. I lightly sanded the result once it had dried then scrubbed it with a very damp sponge to smooth everything back out. This required exercising extreme care to keep the mud off the surface of the nice dirty concrete.