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
Any better ways to weather concrete?
Note: it's only a small patch so I was hoping for something simple and
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
There's other "issues" with patching concrete depending on what you're
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
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.
IMO, since it's a real millstone, the axle hole should stand out.
I'd get any color pre-mix in a can. Black might look good.
Haven't done so I don't know which product, but I bet you could find
something in a can quick browsing at the store.
Cutting a piece of rubber to fit and gluing/epoxying it in might work.
We used ready-mixed stucco patch on our condo's conc. block/stucco both
to patch broken stucco and as mortar to cover a hole with a concrete
paver :o) It was to be painted and looked great afterward. For such a
small defect as you describe, it would probably work but would need to
be painted. Doubt it would last forever, but the precise center is
probably not stepped on very often. Paintable, and acryllic craft paint
is close enough to exterior paint. Or take some exterior paint,
leftover, and mix in a tad bit of acryllic artist color. I've used
artist colors...acryllic or oil...for scads of jobs that didn't need the
quart/gallon size of anything. Have mixed up my own "paint" from
varnish, stain from oil paints, lin. oil, min. spirits and a pinch of
varnish. The stucco patch comes sanded and unsanded, don't recall if it
is colored. If you rub some stones on the millstone, you could probably
end up with enough ground stone to color the stuff you patch with. I
don't use any reference texts...just mix up what I think will do the job :o)
Interesting question. Since the space is only about 1/4 to 1/8 inch thick,
I wonder how well whatever you put in there will stay in place. Maybe the
suggestion about using tile grout will work, or maybe using concrete patch
that they sell at Home Depot etc. will be better than mortar or regular
I did a Google search of online images for millstones. To do the same
search, go to http://images.google.com/imghp?hl=en and type in millstone for
the search. Do any of those images look similar to the millstone that you
Whatever you use to fill the patched area, would it be possible to grind off
part of the millstone in a hidden area and spread that on top to try to do
the match? Or, maybe drill some holes in the center part to help hold the
patch and the use the drill dust on top of the patch to try to match the
I like the drilling or grinding idea - extra work but that sounds like
how an architect would approach it. One other thing: if it was me I
would look at using thinset mortar mix - the stuff you set tile with.
It comes in various colors, seems to be happy being in a thin layer,
and it's sticky. I would favor that over grout. -- H
be careful a buddy cleaned his concrete one summer preping to sell
home in the spring.
he raised the grain of the concrete, damaged the surface. after a hard
winter, cracked and spalled all over....
ended up replacing most of his sidewalk..
he also damaged his deck boards...... cost his a deck rebuild, which
was OK I guess some of the joists were rotting, found when the deck
was pulled up....
he gave away his pressure washer......
NO! Concrete is sacred. Do not defile the mix with filthy additives.
Leave it outside for a couple of decades.
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.
Go to Walmart, Michaels or other craft store, buy a couple of bottles of
acryllic craft paint....mix gray, a touch of yellow, a touch of burnt
umber, dab on lightly with a stiff bristle stencil brush. I used it on
concrete to cover dark wood stain that spilled and it did a very
adequate job. Any paint, if not water soluble, is just about impossible
to remove from concrete.
I've sprinkled iron/steel filings on new concrete then mist it with
water. Cover it with plastic so it has time to rust before it dries
out, keep it wet. I've also mixed some filings in with the concrete but
it's really a guess at how much it will stain.
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