Mold on sidewalk removal

My sister who lives in the Houston area, which is normally high humidity, but has experienced a lot of rain the last couple months, making the mold situation dramatically worse. (I live a couple hundred miles west of her, and we are in our third year of a serious draught).
Anyway, my sister has black mold growing on her sidewalks, patio, and driveway concrete. I suggested she use a garden sprayer (the kind that fits on a hose and has a jar to hold the plant medicine) to spray the concrete with bleach. It would possibly take several applications about a week a part to get rid of all the mold, but it would be easy to do.
The thing I don't know is how heavy the mixture of bleach to water should be. My guess would be about 10% bleach, but that is certainly an uneducated guess.
I hope someone here has had experience with killing mold on concrete, and will advise us on whether bleach is the right approach and what percent, and if not, what the best treatment, then what is.
Thanks in advance.
Bob-tx
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probably 50%

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I'd use a power washer, no bleach necessary.
No point in killing the mold.
--
Dan Espen

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Yes, point. it's toxic, and harmful to humans. A friend of mine got into black mold, put him in the hospital for weeks. He'll never be right, again.
Christopher A. Young Learn more about Jesus www.lds.org .
I'd use a power washer, no bleach necessary.
No point in killing the mold.
--
Dan Espen



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On 1/15/2013 5:33 PM, Stormin Mormon wrote:

Mold grows everywhere it is warm and humid. It is in the air, spores everywhere. Anything in Florida will either rust or grow mold if left outdoors for longer than a day :o)
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.

I agree. I use one to clean the black crud off my patio, sidewalk, and driveway. A whole lot cheaper than a couple of gallons of bleach.
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wrote:

Well, In November, I spent six hours and six gallons of gas cleaning the driveway (and $400 for a pressure washer). A couple of gallons of bleach is cheap! Though I used that too. Didn't work.
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snipped-for-privacy@attt.bizz writes:

For a driveway/patio, a sub $100 electric is more than enough.
--
Dan Espen

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wrote:

That would have only taken me two weeks, rather than six hours. Yeah, a *lot* cheaper.
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On 1/15/2013 9:15 PM, Red wrote:

I also use a power washer but I am sure that it is not cheaper when you add in the cost of the power washer.
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Look here.
http://www.oakland-nj.org/PDF/Hurricane_Flood_page/Hurricane%20Irene%20-%20Public%20Health%20Information.pdf
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On 1/15/2013 5:19 PM, David L. Martel wrote:

http://www.oakland-nj.org/PDF/Hurricane_Flood_page/Hurricane%20Irene%20-%20Public%20Health%20Information.pdf
Didn't have a flood, and not eating off the sidewalks.
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I got black algae on my garage shingles. The cure is oxyclean spray. Black does not mean it has to be mold.
Greg
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wrote:

Good point. Algae is more likely. Not all black mold is created equal, either. Not all black mold is black, either. ;-)
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snipped-for-privacy@attt.bizz wrote:

And, in the Houston area, it could just as easily be dirt. Or at least the particulate matter from engine exhausts.
What you COULD do to help is power-wash the affected concrete, then apply multiple coats of concrete sealer.
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wrote:

If it were dirt here, it would be red, not black.

That's like work[*]. Not sure it's a good idea either.
[*] selling the house.
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On 1/15/2013 4:54 PM, OMB wrote:

10% is plenty strong....I used it on stucco condo walls and it was plenty potent. I would not bother with "several applications" because if it is that persistent then the conditions for growing it are ideal. We had light mold growth around our (Florida) condo in places that got little or no sunlight .. north facing walls and walks shaded by building or landscaping. I cleaned the building because the walls were white and it brightened them up nicely. Always rinsed with plain water and never saw adverse effect on plants, but I'd be careful with more delicate landscaping like rhododendrons, azaleas, etc.
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So many people have reported the common ways that fail, that something radically different comes to mind. Given that situation, I would head to the boat shop and get some antifouling marine paint. Ending up with a brightly colored sidewalk might be a small sacrifice to end the annoyance and hassle of mold removal. Might even start a trend.
Joe
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People are making too much of this. Bleach and water will take care of it but of course it can return in time so in that case you just do it again. You can use a simple spray bottle to do this job. It doesn't need that much spray if you have enough bleach in the solution. And I live in a Houston suburb so I can speak from experience about this stuff.
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