On Dec 2, 11:40*am, blueman wrote:
I need to patch some concrete outside and I want to be able to match the
color (basically 'dirty looking') and make it look old & weathered.

Can I just add a little 'dirt' (i.e. soil) to the mix to make it look
darker and dirtier or will this create problems such as encouraging
organic growth or weakening the concrete (I would only add a little
bit).

NO! Concrete is sacred. Do not defile the mix with filthy additives.

Any better ways to weather concrete?

Leave it outside for a couple of decades.

Note: it's only a small patch so I was hoping for something simple and
cheap...

There actually are some approved colorants to help match the shade,
but not the texture. Check local ready-mix companies, box stores,
Google, etc. If all else fails, a dab of Lock-Ease dry graphite powder
is chemically neutral and will not affect the concrete mix. The dry
results will not resemble the wet mix appearance, so make a dry mix
before adding water to get a close match.

Joe