blueman wrote:
Vic Smith writes:
On Thu, 02 Dec 2010 12:40:53 -0500, 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).

Any better ways to weather concrete?

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

Don't use dirt.
You can try to match the aggregate stone, and the sand by using a
similar color. You can buy coloring also.
Last time I bought mortar color powder was 20 years ago, and it was
about 3 bucks a pound, smallest container being 5 lbs.
Never colored concrete.
If the job is small, you might look at aquarium sand and gravel to
mix in with cheap sand and gravel to your portland.
You'd have to test mixes, letting some set before you could see the
outcome.
There's other "issues" with patching concrete depending on what
you're patching.

The job is *real* small - basically we have an old millstone out
front as a stepping stone to our front porch (it looks really nice).

Whoever put in the millstone, filled the old central hole with
concrete
that matches the stone itself pretty well.
HOWEVER, the fill is about 1/4 -1/8 inch short of the surface, so
water still pools there forming ice in the winter which is
dangerous...

I would like to level it off with a thin veneer of new matching
concrete (erring if anything on the side of being slightly proud of
the
surrounding surface).

I plan to use a latex binder instead of water in the mix so it will
bind better to the old stone and concrete.

I probably only need maybe 8-16 ounces total to make the patch so
buying pounds of colorant seems like a waste...

For such a small batch I didn't want to starty buying and mixing up my
own batch of concrete. So my plan was to use quickrete filtered of any
of the stones plus maybe a little mortar (all of which I have hanging
around) and add a small biit of something to make it look dirtier.

I just need to know what something to use...

Perhaps I would be best off adding some aquarium sand to the mortar
mix
I currently have.

Any suggestions?

grout.

it comes in lots of different colors and is a cement product, so can be
mixed with concrete with no affects. try a couple different colors mixed so
it's blotchy.